This section contains the detail about the StringBuffer classs in java.
Working with StringBuffer class
The string object can't be altered once it was created . Java has a peer class of String, called StringBuffer, which allows strings to be altered. StringBuffer may have characters and substrings inserted in the middle or appended to the end.
Following are some of the key methods of it :
| Methods | Description |
| length() | Finds the current length of a StringBuffer. |
| capacity() | Returns the total allocated capacity. |
| ensureCapacity() | Sets the size of the buffer. |
| setLength() | Sets the length of the buffer within a StringBuffer. |
| charAt() | Returns value of a single character at provided index. |
| setCharAt() | Sets the value of a character at provided index. |
| getChars() | It copies a substring of a StringBuffer into an array. |
| append() | It concatenates the string at the end of the invoking String Buffer object |
| insert() | It inserts one string into another at the specified index. |
| reverse() | It reverses the characters within a StringBuffer object. |
| delete() | Delete characters within a StringBuffer specified by the indexes. |
| deleteCharAt() | Delete the character at the index specified. |
| replace() | Replaces one set of characters with another set inside a StrignBuffer object, specified by the indexes . |
| substring() | Obtains a portion of a StringBuffer specified by the indexes. |
Examples :
append() :
public class AppendStringDemo {
public static void main(String args[]) {
String s;
int x = 12;
StringBuffer strb = new StringBuffer(40);
s = strb.append("x=").append(x).append("!").toString();
System.out.println(s);
}
}
Output :
| C:\Program Files\Java\jdk1.6.0_18\bin>javac AppendStringDemo.java C:\Program Files\Java\jdk1.6.0_18\bin>java AppendStringDemo x=12! |
insert()
public class InsertStringDemo {
public static void main(String args[]) {
StringBuffer strb = new StringBuffer("I Devmanuals! ");
strb.insert(2, "like ");
System.out.println(strb);
}
}
Output :
|
C:\Program Files\Java\jdk1.6.0_18\bin>javac InsertStringDemo.java C:\Program Files\Java\jdk1.6.0_18\bin>java InsertStringDemo I like Devmanuals! |
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