Serializable
, Appendable
, CharSequence
, Comparable<StringBuffer>
public final class StringBuffer extends Object implements Appendable, Serializable, Comparable<StringBuffer>, CharSequence
String
, 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 the append
and insert
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. The append
method always adds these characters at the end of the buffer; the insert
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 call z.append("le")
would cause the string buffer to contain "startle"
, whereas z.insert(4, "le")
would alter the string buffer to contain "starlet"
.
In general, if sb refers to an instance of a StringBuffer
, then sb.append(x)
has the same effect as sb.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. Note that while StringBuffer
is designed to be safe to use concurrently from multiple threads, if the constructor or the append
or insert
operation is passed a source sequence that is shared across threads, the calling code must ensure that the operation has a consistent and unchanging view of the source sequence for the duration of the operation. This could be satisfied by the caller holding a lock during the operation's call, by using an immutable source sequence, or by not sharing the source sequence across threads.
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.
Unless otherwise noted, passing a null
argument to a constructor or method in this class will cause a NullPointerException
to be thrown.
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.
StringBuffer
implements Comparable
but does not override equals
. Thus, the natural ordering of StringBuffer
is inconsistent with equals. Care should be exercised if StringBuffer
objects are used as keys in a SortedMap
or elements in a SortedSet
. See Comparable
, SortedMap
, or SortedSet
for more information.Constructor | Description |
---|---|
StringBuffer() |
Constructs a string buffer with no characters in it and an initial capacity of 16 characters. |
StringBuffer |
Constructs a string buffer with no characters in it and the specified initial capacity. |
StringBuffer |
Constructs a string buffer that contains the same characters as the specified CharSequence . |
StringBuffer |
Constructs a string buffer initialized to the contents of the specified string. |
Modifier and Type | Method | Description |
---|---|---|
StringBuffer |
append |
Appends the string representation of the boolean argument to the sequence. |
StringBuffer |
append |
Appends the string representation of the char argument to this sequence. |
StringBuffer |
append |
Appends the string representation of the char array argument to this sequence. |
StringBuffer |
append |
Appends the string representation of a subarray of the char array argument to this sequence. |
StringBuffer |
append |
Appends the string representation of the double argument to this sequence. |
StringBuffer |
append |
Appends the string representation of the float argument to this sequence. |
StringBuffer |
append |
Appends the string representation of the int argument to this sequence. |
StringBuffer |
append |
Appends the string representation of the long argument to this sequence. |
StringBuffer |
append |
Appends the specified CharSequence to this sequence. |
StringBuffer |
append |
Appends a subsequence of the specified CharSequence to this sequence. |
StringBuffer |
append |
Appends the string representation of the Object argument. |
StringBuffer |
append |
Appends the specified string to this character sequence. |
StringBuffer |
append |
Appends the specified StringBuffer to this sequence. |
StringBuffer |
appendCodePoint |
Appends the string representation of the codePoint argument to this sequence. |
int |
capacity() |
Returns the current capacity. |
char |
charAt |
Returns the char value in this sequence at the specified index. |
IntStream |
chars() |
Returns a stream of int zero-extending the char values from this sequence. |
int |
codePointAt |
Returns the character (Unicode code point) at the specified index. |
int |
codePointBefore |
Returns the character (Unicode code point) before the specified index. |
int |
codePointCount |
Returns the number of Unicode code points in the specified text range of this sequence. |
IntStream |
codePoints() |
Returns a stream of code point values from this sequence. |
int |
compareTo |
Compares two StringBuffer instances lexicographically. |
StringBuffer |
delete |
Removes the characters in a substring of this sequence. |
StringBuffer |
deleteCharAt |
Removes the char at the specified position in this sequence. |
void |
ensureCapacity |
Ensures that the capacity is at least equal to the specified minimum. |
void |
getChars |
Characters are copied from this sequence into the destination character array dst . |
int |
indexOf |
Returns the index within this string of the first occurrence of the specified substring. |
int |
indexOf |
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. |
StringBuffer |
insert |
Inserts the string representation of the boolean argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the char argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the char array argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of a subarray of the str array argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the double argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the float argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the second int argument into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the long argument into this sequence. |
StringBuffer |
insert |
Inserts the specified CharSequence into this sequence. |
StringBuffer |
insert |
Inserts a subsequence of the specified CharSequence into this sequence. |
StringBuffer |
insert |
Inserts the string representation of the Object argument into this character sequence. |
StringBuffer |
insert |
Inserts the string into this character sequence. |
int |
lastIndexOf |
Returns the index within this string of the last occurrence of the specified substring. |
int |
lastIndexOf |
Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index. |
int |
length() |
Returns the length (character count). |
int |
offsetByCodePoints |
Returns the index within this sequence that is offset from the given index by codePointOffset code points. |
StringBuffer |
repeat |
Repeats count copies of the string representation of the codePoint argument to this sequence. |
StringBuffer |
repeat |
Appends count copies of the specified CharSequence cs to this sequence. |
StringBuffer |
replace |
Replaces the characters in a substring of this sequence with characters in the specified String . |
StringBuffer |
reverse() |
Causes this character sequence to be replaced by the reverse of the sequence. |
void |
setCharAt |
The character at the specified index is set to ch . |
void |
setLength |
Sets the length of the character sequence. |
CharSequence |
subSequence |
Returns a new character sequence that is a subsequence of this sequence. |
String |
substring |
Returns a new String that contains a subsequence of characters currently contained in this character sequence. |
String |
substring |
Returns a new String 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. |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
chars, codePoints, isEmpty
public StringBuffer()
public StringBuffer(int capacity)
capacity
- the initial capacity.NegativeArraySizeException
- if the capacity
argument is less than 0
.public StringBuffer(String str)
16
plus the length of the string argument.str
- the initial contents of the buffer.public StringBuffer(CharSequence seq)
CharSequence
. The initial capacity of the string buffer is 16
plus the length of the CharSequence
argument.seq
- the sequence to copy.public int compareTo(StringBuffer another)
StringBuffer
instances lexicographically. This method follows the same rules for lexicographical comparison as defined in the CharSequence.compare(this, another) method. For finer-grained, locale-sensitive String comparison, refer to Collator
.
compareTo
in interface Comparable<StringBuffer>
this
, the current object, but not StringBuffer another
with which this StringBuffer
is compared.another
- the StringBuffer
to be compared with0
if this StringBuffer
contains the same character sequence as that of the argument StringBuffer
; a negative integer if this StringBuffer
is lexicographically less than the StringBuffer
argument; or a positive integer if this StringBuffer
is lexicographically greater than the StringBuffer
argument.public int length()
length
in interface CharSequence
public int capacity()
public void ensureCapacity(int minimumCapacity)
minimumCapacity
argument. 2
. minimumCapacity
argument is nonpositive, this method takes no action and simply returns. Note that subsequent operations on this object can reduce the actual capacity below that requested here.minimumCapacity
- the minimum desired capacity.public void trimToSize()
capacity()
method.public void setLength(int newLength)
newLength
, 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 the newLength
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 the newLength
argument.
The newLength
argument must be greater than or equal to 0
.
newLength
- the new lengthIndexOutOfBoundsException
- if the newLength
argument is negative.public char charAt(int index)
char
value in this sequence at the specified index. The first char
value is at index 0
, the next at index 1
, 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.
charAt
in interface CharSequence
index
- the index of the desired char
value.char
value at the specified index.IndexOutOfBoundsException
- if index
is negative or greater than or equal to length()
.public int codePointAt(int index)
char
values (Unicode code units) and ranges from 0
to CharSequence.length()
- 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 the char
value at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, the char
value at the given index is returned.
index
- the index to the char
valuesindex
IndexOutOfBoundsException
- if the index
argument is negative or not less than the length of this sequence.public int codePointBefore(int index)
char
values (Unicode code units) and ranges from 1
to CharSequence.length()
. If the char
value at (index - 1)
is in the low-surrogate range, (index - 2)
is not negative, and the char
value at (index -
2)
is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If the char
value at index -
1
is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.
index
- the index following the code point that should be returnedIndexOutOfBoundsException
- if the index
argument is less than 1 or greater than the length of this sequence.public int codePointCount(int beginIndex, int endIndex)
beginIndex
and extends to the char
at index endIndex - 1
. Thus the length (in char
s) of the text range is endIndex-beginIndex
. Unpaired surrogates within this sequence count as one code point each.beginIndex
- the index to the first char
of the text range.endIndex
- the index after the last char
of the text range.IndexOutOfBoundsException
- if the beginIndex
is negative, or endIndex
is larger than the length of this sequence, or beginIndex
is larger than endIndex
.public int offsetByCodePoints(int index, int codePointOffset)
index
by codePointOffset
code points. Unpaired surrogates within the text range given by index
and codePointOffset
count as one code point each.index
- the index to be offsetcodePointOffset
- the offset in code pointsIndexOutOfBoundsException
- if index
is negative or larger than the length of this sequence, or if codePointOffset
is positive and the subsequence starting with index
has fewer than codePointOffset
code points, or if codePointOffset
is negative and the subsequence before index
has fewer than the absolute value of codePointOffset
code points.public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
dst
. The first character to be copied is at index srcBegin
; the last character to be copied is at index srcEnd-1
. The total number of characters to be copied is srcEnd-srcBegin
. The characters are copied into the subarray of dst
starting at index dstBegin
and ending at index:
dstbegin + (srcEnd-srcBegin) - 1
srcBegin
- start copying at this offset.srcEnd
- stop copying at this offset.dst
- the array to copy the data into.dstBegin
- offset into dst
.IndexOutOfBoundsException
- if any of the following is true: srcBegin
is negative dstBegin
is negative srcBegin
argument is greater than the srcEnd
argument. srcEnd
is greater than this.length()
. dstBegin+srcEnd-srcBegin
is greater than dst.length
public void setCharAt(int index, char ch)
ch
. This sequence is altered to represent a new character sequence that is identical to the old character sequence, except that it contains the character ch
at position index
. The index argument must be greater than or equal to 0
, and less than the length of this sequence.
index
- the index of the character to modify.ch
- the new character.IndexOutOfBoundsException
- if index
is negative or greater than or equal to length()
.public StringBuffer append(Object obj)
Object
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 then appended
to this character sequence.
obj
- an Object
.public StringBuffer append(String str)
The characters of the String
argument are appended, in order, increasing the length of this sequence by the length of the argument. If str
is null
, 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 argument str
.
str
- a string.public StringBuffer append(StringBuffer sb)
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
).
sb
- the StringBuffer
to append.public StringBuffer append(CharSequence s)
CharSequence
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
is null
, then the four characters "null"
are appended.
append
in interface Appendable
s
- the CharSequence
to append.public StringBuffer append(CharSequence s, int start, int end)
CharSequence
to this sequence. Characters of the argument s
, starting at index start
, are appended, in order, to the contents of this sequence up to the (exclusive) index end
. The length of this sequence is increased by the value of end - 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 argument s
.
If s
is null
, then this method appends characters as if the s parameter was a sequence containing the four characters "null"
.
append
in interface Appendable
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.IndexOutOfBoundsException
- if start
is negative, or start
is greater than end
or end
is greater than s.length()
public StringBuffer append(char[] str)
char
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 then appended
to this character sequence.
str
- the characters to be appended.public StringBuffer append(char[] str, int offset, int len)
char
array argument to this sequence. Characters of the char
array str
, starting at index offset
, are appended, in order, to the contents of this sequence. The length of this sequence increases by the value of len
.
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 then appended
to this character sequence.
str
- the characters to be appended.offset
- the index of the first char
to append.len
- the number of char
s to append.IndexOutOfBoundsException
- if offset < 0
or len < 0
or offset+len > str.length
public StringBuffer append(boolean b)
boolean
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 then appended
to this character sequence.
b
- a boolean
.public StringBuffer append(char c)
char
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 then appended
to this character sequence.
append
in interface Appendable
c
- a char
.public StringBuffer append(int i)
int
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 then appended
to this character sequence.
i
- an int
.public StringBuffer appendCodePoint(int codePoint)
codePoint
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 method Character.toChars(int)
and the character in that array were then appended
to this character sequence.
codePoint
- a Unicode code pointpublic StringBuffer append(long lng)
long
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 then appended
to this character sequence.
lng
- a long
.public StringBuffer append(float f)
float
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 then appended
to this character sequence.
f
- a float
.public StringBuffer append(double d)
double
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 then appended
to this character sequence.
d
- a double
.public StringBuffer delete(int start, int end)
start
and extends to the character at index end - 1
or to the end of the sequence if no such character exists. If start
is equal to end
, no changes are made.start
- The beginning index, inclusive.end
- The ending index, exclusive.StringIndexOutOfBoundsException
- if start
is negative, greater than length()
, or greater than end
.public StringBuffer deleteCharAt(int index)
char
at the specified position in this sequence. This sequence is shortened by one char
. 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 calling Character.charCount(thisSequence.codePointAt(index))
, where thisSequence
is this sequence.
index
- Index of char
to removeStringIndexOutOfBoundsException
- if the index
is negative or greater than or equal to length()
.public StringBuffer replace(int start, int end, String str)
String
. The substring begins at the specified start
and extends to the character at index end - 1
or to the end of the sequence if no such character exists. First the characters in the substring are removed and then the specified String
is inserted at start
. (This sequence will be lengthened to accommodate the specified String if necessary.)start
- The beginning index, inclusive.end
- The ending index, exclusive.str
- String that will replace previous contents.StringIndexOutOfBoundsException
- if start
is negative, greater than length()
, or greater than end
.public String substring(int start)
String
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.start
- The beginning index, inclusive.StringIndexOutOfBoundsException
- if start
is less than zero, or greater than the length of this object.public CharSequence subSequence(int start, int end)
An invocation of this method of the form
sb.subSequence(begin, end)
behaves in exactly the same way as the invocation
sb.substring(begin, end)
This method is provided so that this class can implement the CharSequence
interface.subSequence
in interface CharSequence
start
- the start index, inclusive.end
- the end index, exclusive.IndexOutOfBoundsException
- if start
or end
are negative, if end
is greater than length()
, or if start
is greater than end
public String substring(int start, int end)
String
that contains a subsequence of characters currently contained in this sequence. The substring begins at the specified start
and extends to the character at index end - 1
.start
- The beginning index, inclusive.end
- The ending index, exclusive.StringIndexOutOfBoundsException
- if start
or end
are negative or greater than length()
, or start
is greater than end
.public StringBuffer insert(int index, char[] str, int offset, int len)
str
array argument into this sequence. The subarray begins at the specified offset
and extends len
char
s. The characters of the subarray are inserted into this sequence at the position indicated by index
. The length of this sequence increases by len
char
s.index
- position at which to insert subarray.str
- A char
array.offset
- the index of the first char
in subarray to be inserted.len
- the number of char
s in the subarray to be inserted.StringIndexOutOfBoundsException
- if index
is negative or greater than length()
, or offset
or len
are negative, or (offset+len)
is greater than str.length
.public StringBuffer insert(int offset, Object obj)
Object
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.obj
- an Object
.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, String str)
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. If str
is null
, then the four characters "null"
are inserted into this sequence.
The character at index k in the new character sequence is equal to:
offset
-offset
in the argument str
, if k is not less than offset
but is less than offset+str.length()
-str.length()
in the old character sequence, if k is not less than offset+str.length()
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.str
- a string.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, char[] str)
char
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.str
- a character array.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int dstOffset, CharSequence s)
CharSequence
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
is null
, then the four characters "null"
are inserted into this sequence.
dstOffset
- the offset.s
- the sequence to be insertedIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int dstOffset, CharSequence s, int start, int end)
CharSequence
into this sequence. The subsequence of the argument s
specified by start
and end
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 by end - start
.
The character at index k in this sequence becomes equal to:
dstOffset
+start-dstOffset
in the argument s
, if k is greater than or equal to dstOffset
but is less than dstOffset+end-start
-(end-start)
in this sequence, if k is greater than or equal to dstOffset+end-start
The dstOffset
argument must be greater than or equal to 0
, 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
is null
, then this method inserts characters as if the s parameter was a sequence containing the four characters "null"
.
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.IndexOutOfBoundsException
- if dstOffset
is negative or greater than this.length()
, or start
or end
are negative, or start
is greater than end
or end
is greater than s.length()
public StringBuffer insert(int offset, boolean b)
boolean
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.b
- a boolean
.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, char c)
char
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.c
- a char
.IndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, int i)
int
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.i
- an int
.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, long l)
long
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.l
- a long
.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, float f)
float
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.f
- a float
.StringIndexOutOfBoundsException
- if the offset is invalid.public StringBuffer insert(int offset, double d)
double
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 then inserted
into this character sequence at the indicated offset.
The offset
argument must be greater than or equal to 0
, and less than or equal to the length of this sequence.
offset
- the offset.d
- a double
.StringIndexOutOfBoundsException
- if the offset is invalid.public int indexOf(String str)
The returned index is the smallest value k
for which:
this.toString().startsWith(str, k)
If no such value of k
exists, then -1
is returned.str
- the substring to search for.-1
if there is no such occurrence.public int indexOf(String str, int fromIndex)
The returned index is the smallest value k
for which:
k >= Math.min(fromIndex, this.length()) &&
this.toString().startsWith(str, k)
If no such value of k
exists, then -1
is returned.str
- the substring to search for.fromIndex
- the index from which to start the search.-1
if there is no such occurrence.public int lastIndexOf(String str)
this.length()
. The returned index is the largest value k
for which:
this.toString().startsWith(str, k)
If no such value of k
exists, then -1
is returned.str
- the substring to search for.-1
if there is no such occurrence.public int lastIndexOf(String str, int fromIndex)
The returned index is the largest value k
for which:
k <= Math.min(fromIndex, this.length()) &&
this.toString().startsWith(str, k)
If no such value of k
exists, then -1
is returned.str
- the substring to search for.fromIndex
- the index to start the search from.-1
if there is no such occurrence.public StringBuffer reverse()
char
values) just prior to execution of the reverse
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.
public StringBuffer repeat(int codePoint, int count)
count
copies of the string representation of the codePoint
argument to this sequence. The length of this sequence increases by count
times the string representation length.
It is usual to use char
expressions for code points. For example:
// insert 10 asterisks into the buffer
sb.repeat('*', 10);
codePoint
- code point to appendcount
- number of times to copyIllegalArgumentException
- if the specified codePoint
is not a valid Unicode code point or if count
is negative.public StringBuffer repeat(CharSequence cs, int count)
count
copies of the specified CharSequence
cs
to this sequence. The length of this sequence increases by count
times the CharSequence
length.
If cs
is null
, then the four characters "null"
are repeated into this sequence.
cs
- a CharSequence
count
- number of times to copyIllegalArgumentException
- if count
is negativepublic String toString()
String
object is allocated and initialized to contain the character sequence currently represented by this object. This String
is then returned. Subsequent changes to this sequence do not affect the contents of the String
.toString
in interface CharSequence
public IntStream chars()
int
zero-extending the char
values from this sequence. Any char which maps to a surrogate code point is passed through uninterpreted. The stream binds to this sequence when the terminal stream operation commences (specifically, for mutable sequences the spliterator for the stream is late-binding). If the sequence is modified during that operation then the result is undefined.
chars
in interface CharSequence
public IntStream codePoints()
int
values which are then passed to the stream. The stream binds to this sequence when the terminal stream operation commences (specifically, for mutable sequences the spliterator for the stream is late-binding). If the sequence is modified during that operation then the result is undefined.
codePoints
in interface CharSequence
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/StringBuffer.html