- java.lang.Object
-
- java.lang.StringBuffer
-
- All Implemented Interfaces:
- Serializable, Appendable, CharSequence
public final class StringBuffer extends Object implements Serializable, CharSequence
A thread-safe, mutable sequence of characters. A string buffer is like aString
, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls.String buffers are safe for use by multiple threads. The methods are synchronized where necessary so that all the operations on any particular instance behave as if they occur in some serial order that is consistent with the order of the method calls made by each of the individual threads involved.
The principal operations on a
StringBuffer
are theappend
andinsert
methods, which are overloaded so as to accept data of any type. Each effectively converts a given datum to a string and then appends or inserts the characters of that string to the string buffer. Theappend
method always adds these characters at the end of the buffer; theinsert
method adds the characters at a specified point.For example, if
z
refers to a string buffer object whose current contents are "start
", then the method callz.append("le")
would cause the string buffer to contain "startle
", whereasz.insert(4, "le")
would alter the string buffer to contain "starlet
".In general, if sb refers to an instance of a
StringBuffer
, thensb.append(x)
has the same effect assb.insert(sb.length(), x)
.Whenever an operation occurs involving a source sequence (such as appending or inserting from a source sequence) this class synchronizes only on the string buffer performing the operation, not on the source.
Every string buffer has a capacity. As long as the length of the character sequence contained in the string buffer does not exceed the capacity, it is not necessary to allocate a new internal buffer array. If the internal buffer overflows, it is automatically made larger. As of release JDK 5, this class has been supplemented with an equivalent class designed for use by a single thread,
StringBuilder
. The StringBuilder class should generally be used in preference to this one, as it supports all of the same operations but it is faster, as it performs no synchronization.- Since:
- JDK1.0
- See Also:
StringBuilder
,String
, Serialized Form
-
-
Constructor Summary
Constructors Constructor and Description StringBuffer()
Constructs a string buffer with no characters in it and an initial capacity of 16 characters.StringBuffer(CharSequence seq)
Constructs a string buffer that contains the same characters as the specifiedCharSequence
.StringBuffer(int capacity)
Constructs a string buffer with no characters in it and the specified initial capacity.StringBuffer(String str)
Constructs a string buffer initialized to the contents of the specified string.
-
Method Summary
Methods Modifier and Type Method and Description StringBuffer
append(boolean b)
Appends the string representation of theboolean
argument to the sequence.StringBuffer
append(char c)
Appends the string representation of thechar
argument to this sequence.StringBuffer
append(char[] str)
Appends the string representation of thechar
array argument to this sequence.StringBuffer
append(char[] str, int offset, int len)
Appends the string representation of a subarray of thechar
array argument to this sequence.StringBuffer
append(CharSequence s)
Appends the specifiedCharSequence
to this sequence.StringBuffer
append(CharSequence s, int start, int end)
Appends a subsequence of the specifiedCharSequence
to this sequence.StringBuffer
append(double d)
Appends the string representation of thedouble
argument to this sequence.StringBuffer
append(float f)
Appends the string representation of thefloat
argument to this sequence.StringBuffer
append(int i)
Appends the string representation of theint
argument to this sequence.StringBuffer
append(long lng)
Appends the string representation of thelong
argument to this sequence.StringBuffer
append(Object obj)
Appends the string representation of theObject
argument.StringBuffer
append(String str)
Appends the specified string to this character sequence.StringBuffer
append(StringBuffer sb)
Appends the specified StringBuffer to this sequence.StringBuffer
appendCodePoint(int codePoint)
Appends the string representation of thecodePoint
argument to this sequence.int
capacity()
Returns the current capacity.char
charAt(int index)
Returns thechar
value in this sequence at the specified index.int
codePointAt(int index)
Returns the character (Unicode code point) at the specified index.int
codePointBefore(int index)
Returns the character (Unicode code point) before the specified index.int
codePointCount(int beginIndex, int endIndex)
Returns the number of Unicode code points in the specified text range of this sequence.StringBuffer
delete(int start, int end)
Removes the characters in a substring of this sequence.StringBuffer
deleteCharAt(int index)
Removes thechar
at the specified position in this sequence.void
ensureCapacity(int minimumCapacity)
Ensures that the capacity is at least equal to the specified minimum.void
getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
Characters are copied from this sequence into the destination character arraydst
.int
indexOf(String str)
Returns the index within this string of the first occurrence of the specified substring.int
indexOf(String str, int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.StringBuffer
insert(int offset, boolean b)
Inserts the string representation of theboolean
argument into this sequence.StringBuffer
insert(int offset, char c)
Inserts the string representation of thechar
argument into this sequence.StringBuffer
insert(int offset, char[] str)
Inserts the string representation of thechar
array argument into this sequence.StringBuffer
insert(int index, char[] str, int offset, int len)
Inserts the string representation of a subarray of thestr
array argument into this sequence.StringBuffer
insert(int dstOffset, CharSequence s)
Inserts the specifiedCharSequence
into this sequence.StringBuffer
insert(int dstOffset, CharSequence s, int start, int end)
Inserts a subsequence of the specifiedCharSequence
into this sequence.StringBuffer
insert(int offset, double d)
Inserts the string representation of thedouble
argument into this sequence.StringBuffer
insert(int offset, float f)
Inserts the string representation of thefloat
argument into this sequence.StringBuffer
insert(int offset, int i)
Inserts the string representation of the secondint
argument into this sequence.StringBuffer
insert(int offset, long l)
Inserts the string representation of thelong
argument into this sequence.StringBuffer
insert(int offset, Object obj)
Inserts the string representation of theObject
argument into this character sequence.StringBuffer
insert(int offset, String str)
Inserts the string into this character sequence.int
lastIndexOf(String str)
Returns the index within this string of the rightmost occurrence of the specified substring.int
lastIndexOf(String str, int fromIndex)
Returns the index within this string of the last occurrence of the specified substring.int
length()
Returns the length (character count).int
offsetByCodePoints(int index, int codePointOffset)
Returns the index within this sequence that is offset from the givenindex
bycodePointOffset
code points.StringBuffer
replace(int start, int end, String str)
Replaces the characters in a substring of this sequence with characters in the specifiedString
.StringBuffer
reverse()
Causes this character sequence to be replaced by the reverse of the sequence.void
setCharAt(int index, char ch)
The character at the specified index is set toch
.void
setLength(int newLength)
Sets the length of the character sequence.CharSequence
subSequence(int start, int end)
Returns a new character sequence that is a subsequence of this sequence.String
substring(int start)
Returns a newString
that contains a subsequence of characters currently contained in this character sequence.String
substring(int start, int end)
Returns a newString
that contains a subsequence of characters currently contained in this sequence.String
toString()
Returns a string representing the data in this sequence.void
trimToSize()
Attempts to reduce storage used for the character sequence.
-
-
-
Constructor Detail
-
StringBuffer
public StringBuffer()
Constructs a string buffer with no characters in it and an initial capacity of 16 characters.
-
StringBuffer
public StringBuffer(int capacity)
Constructs a string buffer with no characters in it and the specified initial capacity.- Parameters:
capacity
- the initial capacity.- Throws:
NegativeArraySizeException
- if thecapacity
argument is less than0
.
-
StringBuffer
public StringBuffer(String str)
Constructs a string buffer initialized to the contents of the specified string. The initial capacity of the string buffer is16
plus the length of the string argument.- Parameters:
str
- the initial contents of the buffer.- Throws:
NullPointerException
- ifstr
isnull
-
StringBuffer
public StringBuffer(CharSequence seq)
Constructs a string buffer that contains the same characters as the specifiedCharSequence
. The initial capacity of the string buffer is16
plus the length of theCharSequence
argument.If the length of the specified
CharSequence
is less than or equal to zero, then an empty buffer of capacity16
is returned.- Parameters:
seq
- the sequence to copy.- Throws:
NullPointerException
- ifseq
isnull
- Since:
- 1.5
-
-
Method Detail
-
length
public int length()
Returns the length (character count).- Specified by:
length
in interfaceCharSequence
- Returns:
- the length of the sequence of characters currently represented by this object
-
capacity
public int capacity()
Returns the current capacity. The capacity is the amount of storage available for newly inserted characters, beyond which an allocation will occur.- Returns:
- the current capacity
-
ensureCapacity
public void ensureCapacity(int minimumCapacity)
Ensures that the capacity is at least equal to the specified minimum. If the current capacity is less than the argument, then a new internal array is allocated with greater capacity. The new capacity is the larger of:- The
minimumCapacity
argument. - Twice the old capacity, plus
2
.
minimumCapacity
argument is nonpositive, this method takes no action and simply returns.- Parameters:
minimumCapacity
- the minimum desired capacity.
- The
-
trimToSize
public void trimToSize()
Attempts to reduce storage used for the character sequence. If the buffer is larger than necessary to hold its current sequence of characters, then it may be resized to become more space efficient. Calling this method may, but is not required to, affect the value returned by a subsequent call to thecapacity()
method.- Since:
- 1.5
-
setLength
public void setLength(int newLength)
Sets the length of the character sequence. The sequence is changed to a new character sequence whose length is specified by the argument. For every nonnegative index k less thannewLength
, the character at index k in the new character sequence is the same as the character at index k in the old sequence if k is less than the length of the old character sequence; otherwise, it is the null character'\u0000'
. In other words, if thenewLength
argument is less than the current length, the length is changed to the specified length.If the
newLength
argument is greater than or equal to the current length, sufficient null characters ('\u0000'
) are appended so that length becomes thenewLength
argument.The
newLength
argument must be greater than or equal to0
.- Parameters:
newLength
- the new length- Throws:
IndexOutOfBoundsException
- if thenewLength
argument is negative.- See Also:
length()
-
charAt
public char charAt(int index)
Returns thechar
value in this sequence at the specified index. The firstchar
value is at index0
, the next at index1
, and so on, as in array indexing.The index argument must be greater than or equal to
0
, and less than the length of this sequence.If the
char
value specified by the index is a surrogate, the surrogate value is returned.- Specified by:
charAt
in interfaceCharSequence
- Parameters:
index
- the index of the desiredchar
value.- Returns:
- the
char
value at the specified index. - Throws:
IndexOutOfBoundsException
- ifindex
is negative or greater than or equal tolength()
.- See Also:
length()
-
codePointAt
public int codePointAt(int index)
Returns the character (Unicode code point) at the specified index. The index refers tochar
values (Unicode code units) and ranges from0
tolength()
- 1
.If the
char
value specified at the given index is in the high-surrogate range, the following index is less than the length of this sequence, and thechar
value at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, thechar
value at the given index is returned.- Parameters:
index
- the index to thechar
values- Returns:
- the code point value of the character at the
index
- Since:
- 1.5
-
codePointBefore
public int codePointBefore(int index)
Returns the character (Unicode code point) before the specified index. The index refers tochar
values (Unicode code units) and ranges from1
tolength()
.If the
char
value at(index - 1)
is in the low-surrogate range,(index - 2)
is not negative, and thechar
value at(index - 2)
is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If thechar
value atindex - 1
is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.- Parameters:
index
- the index following the code point that should be returned- Returns:
- the Unicode code point value before the given index.
- Since:
- 1.5
-
codePointCount
public int codePointCount(int beginIndex, int endIndex)
Returns the number of Unicode code points in the specified text range of this sequence. The text range begins at the specifiedbeginIndex
and extends to thechar
at indexendIndex - 1
. Thus the length (inchar
s) of the text range isendIndex-beginIndex
. Unpaired surrogates within this sequence count as one code point each.- Parameters:
beginIndex
- the index to the firstchar
of the text range.endIndex
- the index after the lastchar
of the text range.- Returns:
- the number of Unicode code points in the specified text range
- Since:
- 1.5
-
offsetByCodePoints
public int offsetByCodePoints(int index, int codePointOffset)
Returns the index within this sequence that is offset from the givenindex
bycodePointOffset
code points. Unpaired surrogates within the text range given byindex
andcodePointOffset
count as one code point each.- Parameters:
index
- the index to be offsetcodePointOffset
- the offset in code points- Returns:
- the index within this sequence
- Since:
- 1.5
-
getChars
public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
Characters are copied from this sequence into the destination character arraydst
. The first character to be copied is at indexsrcBegin
; the last character to be copied is at indexsrcEnd-1
. The total number of characters to be copied issrcEnd-srcBegin
. The characters are copied into the subarray ofdst
starting at indexdstBegin
and ending at index:dstbegin + (srcEnd-srcBegin) - 1
- Parameters:
srcBegin
- start copying at this offset.srcEnd
- stop copying at this offset.dst
- the array to copy the data into.dstBegin
- offset intodst
.- Throws:
NullPointerException
- ifdst
isnull
.IndexOutOfBoundsException
- if any of the following is true:srcBegin
is negativedstBegin
is negative- the
srcBegin
argument is greater than thesrcEnd
argument. srcEnd
is greater thanthis.length()
.dstBegin+srcEnd-srcBegin
is greater thandst.length
-
setCharAt
public void setCharAt(int index, char ch)
The character at the specified index is set toch
. This sequence is altered to represent a new character sequence that is identical to the old character sequence, except that it contains the characterch
at positionindex
.The index argument must be greater than or equal to
0
, and less than the length of this sequence.- Parameters:
index
- the index of the character to modify.ch
- the new character.- Throws:
IndexOutOfBoundsException
- ifindex
is negative or greater than or equal tolength()
.- See Also:
length()
-
append
public StringBuffer append(Object obj)
Appends the string representation of theObject
argument.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(Object)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
obj
- anObject
.- Returns:
- a reference to this object.
-
append
public StringBuffer append(String str)
Appends the specified string to this character sequence.The characters of the
String
argument are appended, in order, increasing the length of this sequence by the length of the argument. Ifstr
isnull
, then the four characters"null"
are appended.Let n be the length of this character sequence just prior to execution of the
append
method. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argumentstr
.- Parameters:
str
- a string.- Returns:
- a reference to this object.
-
append
public StringBuffer append(StringBuffer sb)
Appends the specified StringBuffer to this sequence.The characters of the StringBuffer argument are appended, in order, to the contents of this StringBuffer, increasing the length of this StringBuffer by the length of the argument. If sb is null, then the four characters "null" are appended to this StringBuffer.
Let n be the length of the old character sequence, the one contained in the StringBuffer just prior to execution of the append method. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument
sb
.This method synchronizes on
this
(the destination) object but does not synchronize on the source (sb
).- Parameters:
sb
- the StringBuffer to append.- Returns:
- a reference to this object.
- Since:
- 1.4
-
append
public StringBuffer append(CharSequence s)
Appends the specifiedCharSequence
to this sequence.The characters of the
CharSequence
argument are appended, in order, increasing the length of this sequence by the length of the argument.The result of this method is exactly the same as if it were an invocation of this.append(s, 0, s.length());
This method synchronizes on this (the destination) object but does not synchronize on the source (
s
).If
s
isnull
, then the four characters"null"
are appended.- Specified by:
append
in interfaceAppendable
- Parameters:
s
- theCharSequence
to append.- Returns:
- a reference to this object.
- Since:
- 1.5
-
append
public StringBuffer append(CharSequence s, int start, int end)
Appends a subsequence of the specifiedCharSequence
to this sequence.Characters of the argument
s
, starting at indexstart
, are appended, in order, to the contents of this sequence up to the (exclusive) indexend
. The length of this sequence is increased by the value ofend - start
.Let n be the length of this character sequence just prior to execution of the
append
method. Then the character at index k in this character sequence becomes equal to the character at index k in this sequence, if k is less than n; otherwise, it is equal to the character at index k+start-n in the arguments
.If
s
isnull
, then this method appends characters as if the s parameter was a sequence containing the four characters"null"
.- Specified by:
append
in interfaceAppendable
- Parameters:
s
- the sequence to append.start
- the starting index of the subsequence to be appended.end
- the end index of the subsequence to be appended.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException
- ifstart
is negative, orstart
is greater thanend
orend
is greater thans.length()
- Since:
- 1.5
-
append
public StringBuffer append(char[] str)
Appends the string representation of thechar
array argument to this sequence.The characters of the array argument are appended, in order, to the contents of this sequence. The length of this sequence increases by the length of the argument.
The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(char[])
, and the characters of that string were thenappended
to this character sequence.- Parameters:
str
- the characters to be appended.- Returns:
- a reference to this object.
-
append
public StringBuffer append(char[] str, int offset, int len)
Appends the string representation of a subarray of thechar
array argument to this sequence.Characters of the
char
arraystr
, starting at indexoffset
, are appended, in order, to the contents of this sequence. The length of this sequence increases by the value oflen
.The overall effect is exactly as if the arguments were converted to a string by the method
String.valueOf(char[],int,int)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
str
- the characters to be appended.offset
- the index of the firstchar
to append.len
- the number ofchar
s to append.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException
- ifoffset < 0
orlen < 0
oroffset+len > str.length
-
append
public StringBuffer append(boolean b)
Appends the string representation of theboolean
argument to the sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(boolean)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
b
- aboolean
.- Returns:
- a reference to this object.
-
append
public StringBuffer append(char c)
Appends the string representation of thechar
argument to this sequence.The argument is appended to the contents of this sequence. The length of this sequence increases by
1
.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(char)
, and the character in that string were thenappended
to this character sequence.- Specified by:
append
in interfaceAppendable
- Parameters:
c
- achar
.- Returns:
- a reference to this object.
-
append
public StringBuffer append(int i)
Appends the string representation of theint
argument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(int)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
i
- anint
.- Returns:
- a reference to this object.
-
appendCodePoint
public StringBuffer appendCodePoint(int codePoint)
Appends the string representation of thecodePoint
argument to this sequence.The argument is appended to the contents of this sequence. The length of this sequence increases by
Character.charCount(codePoint)
.The overall effect is exactly as if the argument were converted to a
char
array by the methodCharacter.toChars(int)
and the character in that array were thenappended
to this character sequence.- Parameters:
codePoint
- a Unicode code point- Returns:
- a reference to this object.
- Since:
- 1.5
-
append
public StringBuffer append(long lng)
Appends the string representation of thelong
argument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(long)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
lng
- along
.- Returns:
- a reference to this object.
-
append
public StringBuffer append(float f)
Appends the string representation of thefloat
argument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(float)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
f
- afloat
.- Returns:
- a reference to this object.
-
append
public StringBuffer append(double d)
Appends the string representation of thedouble
argument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(double)
, and the characters of that string were thenappended
to this character sequence.- Parameters:
d
- adouble
.- Returns:
- a reference to this object.
-
delete
public StringBuffer delete(int start, int end)
Removes the characters in a substring of this sequence. The substring begins at the specifiedstart
and extends to the character at indexend - 1
or to the end of the sequence if no such character exists. Ifstart
is equal toend
, no changes are made.- Parameters:
start
- The beginning index, inclusive.end
- The ending index, exclusive.- Returns:
- This object.
- Throws:
StringIndexOutOfBoundsException
- ifstart
is negative, greater thanlength()
, or greater thanend
.- Since:
- 1.2
-
deleteCharAt
public StringBuffer deleteCharAt(int index)
Removes thechar
at the specified position in this sequence. This sequence is shortened by onechar
.Note: If the character at the given index is a supplementary character, this method does not remove the entire character. If correct handling of supplementary characters is required, determine the number of
char
s to remove by callingCharacter.charCount(thisSequence.codePointAt(index))
, wherethisSequence
is this sequence.- Parameters:
index
- Index ofchar
to remove- Returns:
- This object.
- Throws:
StringIndexOutOfBoundsException
- if theindex
is negative or greater than or equal tolength()
.- Since:
- 1.2
-
replace
public StringBuffer replace(int start, int end, String str)
Replaces the characters in a substring of this sequence with characters in the specifiedString
. The substring begins at the specifiedstart
and extends to the character at indexend - 1
or to the end of the sequence if no such character exists. First the characters in the substring are removed and then the specifiedString
is inserted atstart
. (This sequence will be lengthened to accommodate the specified String if necessary.)- Parameters:
start
- The beginning index, inclusive.end
- The ending index, exclusive.str
- String that will replace previous contents.- Returns:
- This object.
- Throws:
StringIndexOutOfBoundsException
- ifstart
is negative, greater thanlength()
, or greater thanend
.- Since:
- 1.2
-
substring
public String substring(int start)
Returns a newString
that contains a subsequence of characters currently contained in this character sequence. The substring begins at the specified index and extends to the end of this sequence.- Parameters:
start
- The beginning index, inclusive.- Returns:
- The new string.
- Throws:
StringIndexOutOfBoundsException
- ifstart
is less than zero, or greater than the length of this object.- Since:
- 1.2
-
subSequence
public CharSequence subSequence(int start, int end)
Returns a new character sequence that is a subsequence of this sequence.An invocation of this method of the form
behaves in exactly the same way as the invocationsb.subSequence(begin, end)
This method is provided so that this class can implement thesb.substring(begin, end)
CharSequence
interface.- Specified by:
subSequence
in interfaceCharSequence
- Parameters:
start
- the start index, inclusive.end
- the end index, exclusive.- Returns:
- the specified subsequence.
- Throws:
IndexOutOfBoundsException
- if start or end are negative, if end is greater than length(), or if start is greater than end- Since:
- 1.4
-
substring
public String substring(int start, int end)
Returns a newString
that contains a subsequence of characters currently contained in this sequence. The substring begins at the specifiedstart
and extends to the character at indexend - 1
.- Parameters:
start
- The beginning index, inclusive.end
- The ending index, exclusive.- Returns:
- The new string.
- Throws:
StringIndexOutOfBoundsException
- ifstart
orend
are negative or greater thanlength()
, orstart
is greater thanend
.- Since:
- 1.2
-
insert
public StringBuffer insert(int index, char[] str, int offset, int len)
Inserts the string representation of a subarray of thestr
array argument into this sequence. The subarray begins at the specifiedoffset
and extendslen
char
s. The characters of the subarray are inserted into this sequence at the position indicated byindex
. The length of this sequence increases bylen
char
s.- Parameters:
index
- position at which to insert subarray.str
- Achar
array.offset
- the index of the firstchar
in subarray to be inserted.len
- the number ofchar
s in the subarray to be inserted.- Returns:
- This object
- Throws:
StringIndexOutOfBoundsException
- ifindex
is negative or greater thanlength()
, oroffset
orlen
are negative, or(offset+len)
is greater thanstr.length
.- Since:
- 1.2
-
insert
public StringBuffer insert(int offset, Object obj)
Inserts the string representation of theObject
argument into this character sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(Object)
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.obj
- anObject
.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int offset, String str)
Inserts the string into this character sequence.The characters of the
String
argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument. Ifstr
isnull
, then the four characters"null"
are inserted into this sequence.The character at index k in the new character sequence is equal to:
- the character at index k in the old character sequence, if
k is less than
offset
- the character at index k
-offset
in the argumentstr
, if k is not less thanoffset
but is less thanoffset+str.length()
- the character at index k
-str.length()
in the old character sequence, if k is not less thanoffset+str.length()
The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.str
- a string.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
- the character at index k in the old character sequence, if
k is less than
-
insert
public StringBuffer insert(int offset, char[] str)
Inserts the string representation of thechar
array argument into this sequence.The characters of the array argument are inserted into the contents of this sequence at the position indicated by
offset
. The length of this sequence increases by the length of the argument.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(char[])
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.str
- a character array.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int dstOffset, CharSequence s)
Inserts the specifiedCharSequence
into this sequence.The characters of the
CharSequence
argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument s.The result of this method is exactly the same as if it were an invocation of this object's
insert
(dstOffset, s, 0, s.length()) method.If
s
isnull
, then the four characters"null"
are inserted into this sequence.- Parameters:
dstOffset
- the offset.s
- the sequence to be inserted- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException
- if the offset is invalid.- Since:
- 1.5
-
insert
public StringBuffer insert(int dstOffset, CharSequence s, int start, int end)
Inserts a subsequence of the specifiedCharSequence
into this sequence.The subsequence of the argument
s
specified bystart
andend
are inserted, in order, into this sequence at the specified destination offset, moving up any characters originally above that position. The length of this sequence is increased byend - start
.The character at index k in this sequence becomes equal to:
- the character at index k in this sequence, if
k is less than
dstOffset
- the character at index k
+start-dstOffset
in the arguments
, if k is greater than or equal todstOffset
but is less thandstOffset+end-start
- the character at index k
-(end-start)
in this sequence, if k is greater than or equal todstOffset+end-start
The
dstOffset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.The start argument must be nonnegative, and not greater than
end
.The end argument must be greater than or equal to
start
, and less than or equal to the length of s.If
s
isnull
, then this method inserts characters as if the s parameter was a sequence containing the four characters"null"
.- Parameters:
dstOffset
- the offset in this sequence.s
- the sequence to be inserted.start
- the starting index of the subsequence to be inserted.end
- the end index of the subsequence to be inserted.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException
- ifdstOffset
is negative or greater thanthis.length()
, orstart
orend
are negative, orstart
is greater thanend
orend
is greater thans.length()
- Since:
- 1.5
- the character at index k in this sequence, if
k is less than
-
insert
public StringBuffer insert(int offset, boolean b)
Inserts the string representation of theboolean
argument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(boolean)
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.b
- aboolean
.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int offset, char c)
Inserts the string representation of thechar
argument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(char)
, and the character in that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.c
- achar
.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int offset, int i)
Inserts the string representation of the secondint
argument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(int)
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.i
- anint
.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int offset, long l)
Inserts the string representation of thelong
argument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(long)
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.l
- along
.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int offset, float f)
Inserts the string representation of thefloat
argument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(float)
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.f
- afloat
.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
insert
public StringBuffer insert(int offset, double d)
Inserts the string representation of thedouble
argument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(double)
, and the characters of that string were theninserted
into this character sequence at the indicated offset.The
offset
argument must be greater than or equal to0
, and less than or equal to the length of this sequence.- Parameters:
offset
- the offset.d
- adouble
.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException
- if the offset is invalid.
-
indexOf
public int indexOf(String str)
Returns the index within this string of the first occurrence of the specified substring. The integer returned is the smallest value k such that:
isthis.toString().startsWith(str, k)
true
.- Parameters:
str
- any string.- Returns:
- if the string argument occurs as a substring within this
object, then the index of the first character of the first
such substring is returned; if it does not occur as a
substring,
-1
is returned. - Throws:
NullPointerException
- ifstr
isnull
.- Since:
- 1.4
-
indexOf
public int indexOf(String str, int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. The integer returned is the smallest value k for which:
If no such value of k exists, then -1 is returned.k >= Math.min(fromIndex, this.length()) && this.toString().startsWith(str, k)
- Parameters:
str
- the substring for which to search.fromIndex
- the index from which to start the search.- Returns:
- the index within this string of the first occurrence of the specified substring, starting at the specified index.
- Throws:
NullPointerException
- ifstr
isnull
.- Since:
- 1.4
-
lastIndexOf
public int lastIndexOf(String str)
Returns the index within this string of the rightmost occurrence of the specified substring. The rightmost empty string "" is considered to occur at the index valuethis.length()
. The returned index is the largest value k such that
is true.this.toString().startsWith(str, k)
- Parameters:
str
- the substring to search for.- Returns:
- if the string argument occurs one or more times as a substring
within this object, then the index of the first character of
the last such substring is returned. If it does not occur as
a substring,
-1
is returned. - Throws:
NullPointerException
- ifstr
isnull
.- Since:
- 1.4
-
lastIndexOf
public int lastIndexOf(String str, int fromIndex)
Returns the index within this string of the last occurrence of the specified substring. The integer returned is the largest value k such that:
If no such value of k exists, then -1 is returned.k <= Math.min(fromIndex, this.length()) && this.toString().startsWith(str, k)
- Parameters:
str
- the substring to search for.fromIndex
- the index to start the search from.- Returns:
- the index within this sequence of the last occurrence of the specified substring.
- Throws:
NullPointerException
- ifstr
isnull
.- Since:
- 1.4
-
reverse
public StringBuffer reverse()
Causes this character sequence to be replaced by the reverse of the sequence. If there are any surrogate pairs included in the sequence, these are treated as single characters for the reverse operation. Thus, the order of the high-low surrogates is never reversed. Let n be the character length of this character sequence (not the length inchar
values) just prior to execution of thereverse
method. Then the character at index k in the new character sequence is equal to the character at index n-k-1 in the old character sequence.Note that the reverse operation may result in producing surrogate pairs that were unpaired low-surrogates and high-surrogates before the operation. For example, reversing "\uDC00\uD800" produces "\uD800\uDC00" which is a valid surrogate pair.
- Returns:
- a reference to this object.
- Since:
- JDK1.0.2
-
toString
public String toString()
Returns a string representing the data in this sequence. A newString
object is allocated and initialized to contain the character sequence currently represented by this object. ThisString
is then returned. Subsequent changes to this sequence do not affect the contents of theString
.- Specified by:
toString
in interfaceCharSequence
- Returns:
- a string representation of this sequence of characters.
-
-
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Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-rf-java/lang/StringBuffer.html
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