Java String substring()

The Java String class substring() method returns a part of the string.

We pass beginIndex and endIndex number position in the Java substring method where beginIndex is inclusive, and endIndex is exclusive. In other words, the beginIndex starts from 0, whereas the endIndex starts from 1.

There are two types of substring methods in Java string.

Signature

If we don’t specify endIndex, the method will return all the characters from startIndex.

Parameters

startIndex : starting index is inclusive

endIndex : ending index is exclusive

Returns

specified string

Exception Throws

StringIndexOutOfBoundsException is thrown when any one of the following conditions is met.

• if the start index is negative value
• end index is lower than starting index.
• Either starting or ending index is greater than the total number of characters present in the string.

Internal implementation substring(int beginIndex)

Internal implementation substring(int beginIndex, int endIndex)

Java String substring() method example

FileName: SubstringExample.java

Test it Now

Output:

va  vatpoint  

Java String substring() Method Example 2

FileName: SubstringExample2.java

Output:

Tutoraspire  point  Exception in thread "main" java.lang.StringIndexOutOfBoundsException: begin 5, end 15, length 10  

Applications of substring() Method

1) The substring() method can be used to do some prefix or suffix extraction. For example, we can have a list of names, and it is required to filter out names with surname as “singh”. The following program shows the same.

FileName: SubstringExample3.java

Output:

Yuvraj Singh  Harbhajan Singh  Gurjit Singh  Sandeep Singh  Milkha Singh  

2) The substring() method can also be used to check whether a string is a palindrome or not.

FileName: SubstringExample4.java

Output:

madam is a palindrome.  rock is not a palindrome.  eye is a palindrome.  noon is a palindrome.  kill is not a palindrome.