Java String substring()

The syntax of the substring() method is:

string.substring(int startIndex, int endIndex)

Here, string is an object of the String class.

substring() Parameters

The substring() method takes two parameters.

• startIndex - the begining index
• endIndex (optional) - the ending index

substring() Return Value

The substring() method returns a substring from the given string.

• The substring beings with the character at the startIndex and extends to the character at index endIndex - 1.
• If the endIndex is not passed, the substring beings with the character at the specified index and extends to the end of the string.

Note: You will get an error if,

• startIndex/endIndex is negative or greater than string's length
• startIndex is greater than endIndex

Example 1: Java substring() Without End Index

class Main {
    public static void main(String[] args) {
        String str1 = "program";

        // from the first character to end
        System.out.println(str1.substring(0));  // program

        // from the 4th character to end
        System.out.println(str1.substring(3));  // gram
    }
}

Example 2: Java substring() With End Index

class Main {
    public static void main(String[] args) {
        String str1 = "program";

        // from 1st to the 7th  character
        System.out.println(str1.substring(0, 7));  // program

        // from 1st to the 5th  character
        System.out.println(str1.substring(0, 5));  // progr

        // from 4th to the 5th character
        System.out.println(str1.substring(3, 5));  // gr
    }
}

If you need to find the index of the first occurrence of the specified substring from a given string, use the Java String indexOf().