Java学习笔记13---一个循环程序的设计范例

package welcome;

import java.util.Scanner;
/*
 * 一个循环程序的设计范例
 * 首先编写仅执行一次的程序(当无循环时)
 * 循环的设计步骤:
 * 1.确定程序中要重复执行的部分;
 * 2.加上循环模板 while(true){语句块;}
 * 3.重写循环控制条件,增加循环控制语句
 */

public class SubtrationQuizLoop {
    public static void main(String[] args) {
        final int NUMBER_OF_QUESTIONS = 5;
        int correctCount = 0;
        String output = "";
        long startTime = System.currentTimeMillis();
        Scanner in = new Scanner(System.in);
        
        int count = 0;
        while(count < NUMBER_OF_QUESTIONS){  // 重写循环控制条件,增加循环控制语句
        int number1 = (int) (Math.random() * 10);
        int number2 = (int) (Math.random() * 10);

        if (number1 < number2) {
            int temp = number1;
            number1 = number2;
            number2 = temp;
        }

        System.out.print(" What is " + number1 + " - " + number2 + " ? ");
        int answer = in.nextInt();

        if (number1 - number2 == answer) {
            System.out.println("You are correct!");
            correctCount++;
        } else {
            System.out.println(
                    "Your answer is wrong.
" + number1 + " - " + number2 + " should be " + (number1 - number2));
        }
        count++;
        output += "
" + number1 + "-" + number2 + "=" + answer + ((number1 - number2 == answer)? " correct" : " wrong");
    }
        long endTime = System.currentTimeMillis();
        long testTime = endTime - startTime;
        System.out.println("Correct count is " + correctCount + "
Test time is " + testTime / 1000 + " seconds
" + output);
 }
}

运行效果:

设计过程截图:

无循环的程序版本(截图):

运行示例:

循环程序设计第二步,加循环模板

第三步,重写循环继续条件,增加循环控制语句

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