Question

如果我这样称呼：

math a = new math ();
for (x=0; ×<5;x++){
    a.addition ();
}

在主要班级^

import java.util.*;
public class math
{   
    Scanner scan = new     Scanner(System.in);
        Random rand = new Random();
        private int num1 = rand.nextInt(100);
        private int num2 = rand.nextInt(100);
      private int correctanswers = 0;

public void addition(){
    System.out.println(num1 + " + " + num2 + " = ");
    int answer = scan.nextInt();
    if (answer == (num1 + num2)){
           correctanswers++;
    }
}

    public int getcorrectanswers(){
    return correctanswers;
    }
}

每次绕过＆＃39;对于＆＃39;来说，我得到的是相同的数字。循环（5次）我想知道的是，每当它越过＆＃39;对于＆＃39;当a.addition（）被调用时循环例如：每次打印5 + 7而不是每次打2个不同的数字显然我想要的是5 + 2然后4 + 50等。

Answer 1

那是因为

private int num1 = rand.nextInt(100);
private int num2 = rand.nextInt(100);

是数学对象的字段。两者都在new math()上初始化一次。

将它们作为局部变量放在addition方法中：

public void addition(){
    int num1 = rand.nextInt(100);
    int num2 = rand.nextInt(100);
    System.out.println(num1 + " + " + num2 + " = ");
    int answer = scan.nextInt();
    if (answer == (num1 + num2)){
           correctanswers++;
    }
}

Answer 2

每次调用addition（）时，数学类中的random int都是相同的。添加到'添加' - ＆gt; num1 = r.nextInt（）获取'num1'的新随机数

Java对象和随机数

2 个答案: