Question

好的，所以这里是：我要求提取的数字然后询问抽出的数字
然后当我转到它，如果他们匹配它告诉我 pickOne 无法解决但我使用用户＆＃39;输入，我做错了什么？

我在视线上搜索了多件事似乎没有出现同样的问题。所以，如果我找不到答案的话，我很难道。我确实搜索了大约30分钟。

代码：

import java.util.Scanner;
import java.util.*;


public class CheckNumber {  
    public static void main(String[] args){

     Scanner userInput = new Scanner(System.in);

        int matchOne;
        int matchTwo;
        int matchThree;
        int matchFour;

        /*
         * 
         ********** THE NUMBERS CHOSEN BY USER **********
         *
        */

        System.out.println("First number picked: ");

        if (userInput.hasNextInt()){

            int pickOne = userInput.nextInt();

        }

        System.out.println("Second number picked: ");

        if (userInput.hasNextInt()){

            int pickTwo = userInput.nextInt();

        }

        System.out.println("Third number picked: ");

        if (userInput.hasNextInt()){
            int pickThree = userInput.nextInt();    
        }

        System.out.println("Fourth number picked: ");

        if (userInput.hasNextInt()){

            int pickFour = userInput.nextInt();

        }

        /*
         * 
         ********** THE WINNING NUMBERS DRAWN **********
         *      
        */

        System.out.println("First number drawn: ");

        if (userInput.hasNextInt()){
            int drawnOne = userInput.nextInt();
        }

        System.out.println("First number drawn: ");

        if (userInput.hasNextInt()){
            int drawnTwo = userInput.nextInt();
        }

        System.out.println("First number drawn: ");

        if (userInput.hasNextInt()){
            int drawnThree = userInput.nextInt();
        }

        System.out.println("First number drawn: ");

        if (userInput.hasNextInt()){
            int drawnFour = userInput.nextInt();
        }

        /*
         ********** MATCHING NUMBERS **********
        */

以下是问题：

        if (pickOne == drawnOne){
            System.out.println(pickOne + " is a match!");
        }

    }

}

Answer 1

输入和输出是什么。举一些例子。我没有好好利用 if（userInput.hasNextInt（））

你的意思是这样吗？

import java.util.Scanner;
import java.util.*;

public class CheckNumber {
    public static void main(String[] args) {

        Scanner userInput = new Scanner(System.in);

        int matchOne;
        int matchTwo;
        int matchThree;
        int matchFour;

        int pickOne;
        int pickTwo;
        int pickThree;
        int pickFour;

        int drawnOne;
        int drawnTwo;
        int drawnThree;
        int drawnFour;

        /*
         ********** THE NUMBERS CHOSEN BY USER **********
         */

        System.out.println("First number picked: ");
        pickOne = userInput.nextInt();

        System.out.println("Second number picked: ");
        pickTwo = userInput.nextInt();

        System.out.println("Third number picked: ");
        pickThree = userInput.nextInt();

        System.out.println("Fourth number picked: ");
        pickFour = userInput.nextInt();

        /*
         * 
         ********** THE WINNING NUMBERS DRAWN **********
         * 
         */

        System.out.println("First number drawn: ");
        drawnOne = userInput.nextInt();

        System.out.println("Second number drawn: ");
        drawnTwo = userInput.nextInt();

        System.out.println("Third number drawn: ");
        drawnThree = userInput.nextInt();

        System.out.println("Fourth number drawn: ");
        drawnFour = userInput.nextInt();

        /*
         ********** MATCHING NUMBERS **********
         */

        if (pickOne == drawnOne) {
            System.out.println(pickOne + " is a match!");
        }

    }

}

Answer 2

块中定义的变量只能从块中访问。在您的计划中，pickedOne，pickedTwo，......，drawOne，drawTwo，......变量的范围仅限于{{1}你声明它们的块。因此，如果您尝试在if条件之外使用它们，则会收到错误消息if。

在cannot find symbol函数内声明以下变量，而不是在main()条件内。

if

我强烈建议你阅读scope of variables in Java。

变量/用户输入无法解决

2 个答案: