Java StringBuilder Class

StringBuilder Class Introduction

The Java StringBuilder class is mutable sequence of characters. This provides an API compatible with StringBuffer, but with no guarantee of synchronization. StringBuilder class can be used to replace StringBuffer where single threaded operations are in use. As StringBuffer has overhead of synchronization, StringBuilder acts as a faster alternative of StringBuffer. In case of multi-threaded environment, where we need to synchronized string manipulation operations, StringBuffer is recommanded, otherwise StringBuilder is to be used to improve performance.

StringBuilder Class Declaration

Following is the declaration for java.lang.StringBuilder class −

public final class StringBuilder
   extends Object
      implements Serializable, CharSequence

StringBuilder Class Constructors

Following is the list of constructors of the StringBuilder class.

StringBuilder Class methods

Following is the list of methods of the StringBuilder class. Each method is having multiple examples to demonstrate the functionality of the method.

Methods inherited

This class inherits methods from the following classes −

• java.lang.Object

• java.lang.CharSequence

Example: Append a Boolean to the StringBuilder

The following example shows the usage of Java StringBuilder append(Boolean b) method. Here, we are instantiating a StringBuilder object "buff" with the string name "tuts". Then, we invoke the append() method using the "buff" object with a boolean argument "true". The return value will be the appended string name "tuts true". Similarly, we demonstrate another case using the string name "abcd" and a boolean argument "false".

package com.tutorialspoint;

public class StringBuilderDemo {

   public static void main(String[] args) {

      StringBuilder stringBuilder = new StringBuilder("tuts ");
      System.out.println("builder = " + stringBuilder);

      // appends the boolean argument as string to the string stringBuilder
      stringBuilder.append(true);
      
      // print the string stringBuilder after appending
      System.out.println("After append = " + stringBuilder);

      stringBuilder = new StringBuilder("abcd ");
      System.out.println("stringBuilder = " + stringBuilder);
      
      // appends the boolean argument as string to the string stringBuilder    
      stringBuilder.append(false);
      
      // print the string stringBuilder after appending
      System.out.println("After append = " + stringBuilder);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

stringBuilder = tuts
After append = tuts true
stringBuilder = abcd
After append = abcd false