String match, find substring Java

topic:

Count the number of occurrences of substrings in a string

import java.util.*;
public class childMatch {
    
    
	public static void main(String args[]){
    
    
	Scanner s = new Scanner(System.in);
	System.out.print("请输入字符串：");
	String str1 = s.nextLine();
	System.out.print("请输入子串：");
	String str2 = s.nextLine();
	int count=0;
	if(str1.equals("")||str2.equals("")){
    
    
		System.out.println("你没有输入字符串或子串,无法比较!");
		System.exit(0);
	}else{
    
    
		for(int i=0;i<=str1.length()-str2.length();i++)	{
    
    
			if(str2.equals(str1.substring(i, str2.length()+i)))
				//这种比法有问题，会把"aaa"看成有 2 个"aa"子串
				count++;
			}
			System.out.println("子串在字符串中出现: "+count+" 次");
		}
	}
}