Java StringBuffer substring()

In this tutorial, we will discuss the Java StringBuffer substring() method with the help of examples.

The syntax of substring() method is:

sb.substring(4) //substring starting from index 4 till end
sb.substring(2, 5) //substring from index 2 till index 5

Here, sb is an object of StringBuffer class.

substring() Description

There are two variations of substring() method in Java StringBuffer class.

public String substring(int startIndex): It returns a substring starting from the specified index startIndex till the end of the given character sequence.

public String substring(int startIndex, int endIndex): It returns a substring starting from the specified index startIndex till the specified index endIndex.

substring() Parameters

It can take upto two parameters. The endIndex parameter is optional.

• startIndex: Specifies the start position of the substring
• endIndex: Specifies the end of the substring

This method throws StringIndexOutOfBoundsException, if any of the following condition occurs:

• If startIndex < 0 or >= length of the string represented by StringBuffer.
• If endIndex < 0 or >= length of the string.
• if startIndex > endIndex.

substring() Return Value

Returns a substring based on the specified indexes.

Example 1: Only startIndex is given

class JavaExample{
  public static void main(String[] args) {
    StringBuffer sb = new StringBuffer("BeginnersBook");
    //substring begins from index 9
    String subStr = sb.substring(9);
    System.out.println("Substring from index 9: "+subStr);
  }
}

Output:

Example 2: Substring using start and end indexes

class JavaExample{
  public static void main(String[] args) {
    StringBuffer sb = new StringBuffer("BeginnersBook");
    //substring from 0 till 5
    String subStr = sb.substring(0, 5);
    System.out.println("Substring from index 0 to 5: "+subStr);
  }
}

Output:

Example 3: If startIndex is greater than endIndex

class JavaExample{
  public static void main(String[] args) {
    StringBuffer sb = new StringBuffer("BeginnersBook");
    //when startIndex is greater than endIndex
    String subStr = sb.substring(5, 2);
    System.out.println("Substring: "+subStr);
  }
}

Output:

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