Java String indexOf(String str) method with example

Java String indexOf(String str) method Returns the index within this string of the first occurrence of the specified substring. The returned index is the smallest value k for which: this.startsWith(str, k)
If no such value of k exists, then -1 is returned.

Method Signature

public int indexOf(String str)

Parameters:

str – the substring to search for.

Returns:

the index of the first occurrence of the specified substring, or -1 if there is no such occurrence.

String indexOf( String str) method internal implementation

public int indexOf(String str) {
        return indexOf(str, 0);
    }

indexOf(String str) method internally calls public int indexOf(String str, int fromIndex) method. Totally four variants of indexOf method there in Java String class.

  1. Java String indexOf(int ch) method with example
  2. Java String indexOf(int ch, int fromIndex) method with example
  3. Java String indexOf(String str) method with example
  4. Java String indexOf(String str, int fromIndex) method with example

Java String indexOf( String str) method example

package com.ehowtonow.java.lang.string;

public class IndexOfExample {

	public static void main(String[] args) {

		String s = "This is ehowtonow java tutorials";
		System.out.println("index of java : " + s.indexOf("java"));
		System.out.println("index of ehowtonow : "+ s.indexOf("ehowtonow"));
		System.out.println("index of tutorials : "+ s.indexOf("tutorials"));
	}

}

Output

index of java : 18
index of ehowtonow : 8
index of tutorials : 23


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