未解析java变量/用户输入

Question

好的，这里是： 我询问所选的号码
然后询问绘制的数字
然后，当我转到所以如果他们匹配它告诉我，pickOne无法解决，但我使用的是用户的输入，我做错了什么

我一眼就搜索了很多东西，似乎都没有发现同样的问题。因此，如果我不善于找到答案（如果答案已被回答），我很抱歉。我搜索了大约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 **********
        */

问题出在这里：

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

    }

}

Answer 1

块中定义的变量只能从块中访问。在您的程序中，pickedOne，pickedTwodrawOne，drawTwo。。。。变量仅限于声明它们的if块。因此，如果您试图在那些if条件之外使用它们，您将得到错误消息，cannot find symbol

在main()函数中声明以下变量，而不是在if条件中声明

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

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

我强烈鼓励你阅读scope of variables in Java

Answer 2

输入和输出是什么。举几个例子。我看不出if（userInput.hasNextInt（））有什么好用

你是说像这样吗

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!");
        }

    }

}