Java使用嵌套循环在另一个字符串中查找一个字符串出现的次数

Question

So I'm new to programming. I'm using java. Right now I have an assignment I can't solve on a website that teaches java.

This is the assignment

Write a program that returns number of occurrences of a string in another string.

Eg

Input:

First String: the

Second String: The children are playing with their toys because they love it.

Output:

3

Note: You should only use nested loops. Don't use methods like indexOf or substring.

public static void main(String[] args) {

Scanner input = new Scanner (System.in);
String a = input.nextLine();
String b = input.nextLine();
String z[]  = b.split(" ");
int number=0;
for (int i =0; i<z.length; i++){

if (z[i].contains(a))number++;  


}
System.out.println(number);

Answer 1

I won't give you too much code, but here are the main talking points:

• You need a way to read the input in. This can be accomplished with a Scanner - it's either from STDIN or a file.
• You need a way to break up each word in the sentence. String#split will help you with that.
• You need a way to ignore the casing of each sentence - toLowerCase() works well here.
• You need to loop over each word in one sentence, as well as each occurrence in the other sentence. Consider that String.split produces a String[] , and you can iterate over that with any standard for loop.

• You need a way to see is a string is contained in another string. String#contains will help - although you want to be very careful on which side you're asking contains a string. For example:

   // This will print true System.out.println("The world".toLowerCase().contains("the")); // This will print false System.out.println("the".contains("The world".toLowerCase())); 

Answer 2

Try this :

import java.util.Scanner;

public class Occurence {

    /**
     * @param args
     */
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        String str1 = input.nextLine();
        String str2 = input.nextLine();
        int count = 0;
        String word[] = str1.split(" ");

        for (int i = 0; i < word.length; i++) {

            if (word[i].toLowerCase().contains(str2.toLowerCase())) {
                count++;
            }
        }
        System.out.println("Occurence = " + count);
    }

}