Java String substring()

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

    // extract substring from index 0 to 3
    System.out.println(str1.substring(0, 4));

  }
}

// Output: java

Syntax of 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 beginning index
• endIndex (optional) - the ending index

substring() Return Value

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

• The substring begins with the character at the startIndex and extends to the character at index endIndex - 1.
• If the endIndex is not passed, the substring begins 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 the end
    System.out.println(str1.substring(0));  // program


    // from the 4th character to the 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().