編寫應用程式，輸入一個子串和一個整串，求該子串在整個字串中出現的次數

import java.util.*;
public class Tetso5 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		System.out.println("請輸入一個整串:");
		String str1 = sc.nextLine();
		System.out.println("請輸入一個子串:");
		String str2 = sc.nextLine();
		int count = 0;
		while(true) {
			int index = str1.indexOf(str2);
			if(index != -1) {
				str1 = str1.substring(index+str2.length(),str1.length());
				count++;
			}else {
				break;
			}
		}
		System.out.println("count = "+count);
		sc.close();
	}

}