Finding sub-strings in Java 6

Question

I looked through the String API in Java 6 and I did not find any method for computing how many times a specific sub-string appears within a given String.

For example, I would like to know how many times "is" or "not" appears in the string "noisxxnotyynotxisi".

I can do the long way with a loop, but I would like to know whether there is a simpler way.

Thanks.

Edit: I'm using Java 6.

Answer 1

Without using an external library, you can use String.indexOf(String str, int fromIndex); in a loop.

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Update This example fully works.

/**
 * @author The Elite Gentleman
 * @since 31 March 2011
 *
 */
public class Test {

    private static final String STR = "noisxxnotyynotxisi";

    public static int count(String str) {
        int count = 0;
        int index = -1;

        //if (STR.lastIndexOf(str) == -1) {
        //  return count;
        //}

        while ((index = STR.indexOf(str, index + 1)) != -1) {
            count++;
        }

        return count;
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println(Test.count("is"));
        System.out.println(Test.count("no"));
    }
}