Class java.lang.StringBuffer
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Class java.lang.StringBuffer
java.lang.Object
|
+----java.lang.StringBuffer
- public class StringBuffer
- extends Object
This Class is a growable buffer for characters. It is mainly used
to create Strings. The compiler uses it to implement the "+" operator.
For example:
"a" + 4 + "c"
is compiled to:
new StringBuffer().append("a").append(4).append("c").toString()
Note that the method toString() does not create a copy of the internal buffer. Instead
the buffer is marked as shared. Any further changes to the buffer will
cause a copy to be made.
- See Also:
- String, ByteArrayOutputStream
-
StringBuffer()
- Constructs an empty String buffer.
-
StringBuffer(int)
- Constructs an empty String buffer with the specified initial length.
-
StringBuffer(String)
- Constructs a String buffer with the specified initial value.
-
append(Object)
- Appends an object to the end of this buffer.
-
append(String)
- Appends a String to the end of this buffer.
-
append(char[])
- Appends an array of characters to the end of this buffer.
-
append(char[], int, int)
- Appends a part of an array of characters to the end of this buffer.
-
append(boolean)
- Appends a boolean to the end of this buffer.
-
append(char)
- Appends a character to the end of this buffer.
-
append(int)
- Appends an integer to the end of this buffer.
-
append(long)
- Appends a long to the end of this buffer.
-
append(float)
- Appends a float to the end of this buffer.
-
append(double)
- Appends a double to the end of this buffer.
-
capacity()
- Returns the current capacity of the String buffer.
-
charAt(int)
- Returns the character at the specified index.
-
copyWhenShared()
- Copies the buffer value if it is shared.
-
ensureCapacity(int)
- Ensures that the capacity of the buffer is at least equal to the
specified minimum.
-
getChars(int, int, char[], int)
- Copies the characters of the specified substring (determined by
srcBegin and srcEnd) into the character array, starting at the
array's dstBegin location.
-
insert(int, Object)
- Inserts an object into the String buffer.
-
insert(int, String)
- Inserts a String into the String buffer.
-
insert(int, char[])
- Inserts an array of characters into the String buffer.
-
insert(int, boolean)
- Inserts a boolean into the String buffer.
-
insert(int, char)
- Inserts a character into the String buffer.
-
insert(int, int)
- Inserts an integer into the String buffer.
-
insert(int, long)
- Inserts a long into the String buffer.
-
insert(int, float)
- Inserts a float into the String buffer.
-
insert(int, double)
- Inserts a double into the String buffer.
-
length()
- Returns the length (character count) of the buffer.
-
setCharAt(int, char)
- Changes the character at the specified index to be ch.
-
setLength(int)
- Sets the length of the String.
-
toString()
- Converts to a String representing the data in the buffer.
StringBuffer
public StringBuffer()
- Constructs an empty String buffer.
StringBuffer
public StringBuffer(int length)
- Constructs an empty String buffer with the specified initial length.
- Parameters:
- length - the initial length
StringBuffer
public StringBuffer(String str)
- Constructs a String buffer with the specified initial value.
- Parameters:
- str - the initial value of the buffer
length
public int length()
- Returns the length (character count) of the buffer.
capacity
public int capacity()
- Returns the current capacity of the String buffer. The capacity
is the amount of storage available for newly inserted
characters; beyond which an allocation will occur.
copyWhenShared
protected void copyWhenShared()
- Copies the buffer value if it is shared.
ensureCapacity
public synchronized void ensureCapacity(int minimumCapacity)
- Ensures that the capacity of the buffer is at least equal to the
specified minimum.
- Parameters:
- minimumCapacity - the minimum desired capacity
setLength
public synchronized void setLength(int newLength)
- Sets the length of the String. If the length is reduced, characters
are lost. If the length is extended, the values of the new characters
are set to 0.
- Parameters:
- newLength - the new length of the buffer
- Throws: StringIndexOutOfBoundsException
- If the length is invalid.
charAt
public synchronized char charAt(int index)
- Returns the character at the specified index. An index ranges
from 0..length()-1.
- Parameters:
- index - the index of the desired character
- Throws: StringIndexOutOfBoundsException
- If the index is invalid.
getChars
public synchronized void getChars(int srcBegin,
int srcEnd,
char dst[],
int dstBegin)
- Copies the characters of the specified substring (determined by
srcBegin and srcEnd) into the character array, starting at the
array's dstBegin location. Both srcBegin and srcEnd must be legal
indexes into the buffer.
- Parameters:
- srcBegin - begin copy at this offset in the String
- srcEnd - stop copying at this offset in the String
- dst - the array to copy the data into
- dstBegin - offset into dst
- Throws: StringIndexOutOfBoundsException
- If there is an invalid index into the buffer.
setCharAt
public synchronized void setCharAt(int index,
char ch)
- Changes the character at the specified index to be ch.
- Parameters:
- index - the index of the character
- ch - the new character
- Throws: StringIndexOutOfBoundsException
- If the index is invalid.
append
public synchronized StringBuffer append(Object obj)
- Appends an object to the end of this buffer.
- Parameters:
- obj - the object to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public synchronized StringBuffer append(String str)
- Appends a String to the end of this buffer.
- Parameters:
- str - the String to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public synchronized StringBuffer append(char str[])
- Appends an array of characters to the end of this buffer.
- Parameters:
- str - the characters to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public synchronized StringBuffer append(char str[],
int offset,
int len)
- Appends a part of an array of characters to the end of this buffer.
- Parameters:
- str - the characters to be appended
- offset - where to start
- len - the number of characters to add
- Returns:
- the StringBuffer itself, NOT a new one.
append
public StringBuffer append(boolean b)
- Appends a boolean to the end of this buffer.
- Parameters:
- b - the boolean to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public synchronized StringBuffer append(char c)
- Appends a character to the end of this buffer.
- Parameters:
- ch - the character to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public StringBuffer append(int i)
- Appends an integer to the end of this buffer.
- Parameters:
- i - the integer to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public StringBuffer append(long l)
- Appends a long to the end of this buffer.
- Parameters:
- l - the long to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public StringBuffer append(float f)
- Appends a float to the end of this buffer.
- Parameters:
- f - the float to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
append
public StringBuffer append(double d)
- Appends a double to the end of this buffer.
- Parameters:
- d - the double to be appended
- Returns:
- the StringBuffer itself, NOT a new one.
insert
public synchronized StringBuffer insert(int offset,
Object obj)
- Inserts an object into the String buffer.
- Parameters:
- offset - the offset at which to insert
- obj - the object to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public synchronized StringBuffer insert(int offset,
String str)
- Inserts a String into the String buffer.
- Parameters:
- offset - the offset at which to insert
- str - the String to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public synchronized StringBuffer insert(int offset,
char str[])
- Inserts an array of characters into the String buffer.
- Parameters:
- offset - the offset at which to insert
- str - the characters to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public StringBuffer insert(int offset,
boolean b)
- Inserts a boolean into the String buffer.
- Parameters:
- offset - the offset at which to insert
- b - the boolean to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public synchronized StringBuffer insert(int offset,
char c)
- Inserts a character into the String buffer.
- Parameters:
- offset - the offset at which to insert
- ch - the character to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset invalid.
insert
public StringBuffer insert(int offset,
int i)
- Inserts an integer into the String buffer.
- Parameters:
- offset - the offset at which to insert
- i - the integer to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public StringBuffer insert(int offset,
long l)
- Inserts a long into the String buffer.
- Parameters:
- offset - the offset at which to insert
- l - the long to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public StringBuffer insert(int offset,
float f)
- Inserts a float into the String buffer.
- Parameters:
- offset - the offset at which to insert
- f - the float to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
insert
public StringBuffer insert(int offset,
double d)
- Inserts a double into the String buffer.
- Parameters:
- offset - the offset at which to insert
- d - the double to insert
- Returns:
- the StringBuffer itself, NOT a new one.
- Throws: StringIndexOutOfBoundsException
- If the offset is invalid.
toString
public String toString()
- Converts to a String representing the data in the buffer.
- Overrides:
- toString in class Object
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