5.1  1 public class Demo { 2     public static void main(String[] args) { 3         // 创建一个输入对象 4         java.util.Scanner input = new java.util.Scanner(System.in); 5         System.out.print("Enter an integer,the input ends if it is 0: "); 6         //输入一串整数以空格隔开，如果输入0，程序结束 7         int num = input.nextInt(); 8         //定义正数与负数的个数变量，定义输入值得总和（不包括0） 9         int positiveNum = 0, negativeNum = 0;10         double sum = 0;11         //判断输入的第一个整数是否为0，如果不是，继续判断，如果是，直接else12         if (num != 0) {13             //读入的整数计算正数个数、负数个数、总和，直到读入为0跳出循环14             while (num != 0) {15                 if (num > 0)16                     positiveNum++;17                 else18                     negativeNum++;19                 sum += num;20                 num = input.nextInt();21             }22             //输出相应的正数、负数、总和和平均数的值23             System.out.println("The number of positives is " + positiveNum);24             System.out.println("The number of negatives is " + negativeNum);25             System.out.println("The total is " + sum);26             System.out.println("The average is " + sum27                     / (positiveNum + negativeNum));28         }else29             System.out.println("No numbers are entered except 0");30     }31 }

 

5.2  1 public class Demo { 2     public static void main(String[] args) { 3         // 定义问题的数量为10 4         final int NUMBER_OF_QUESTIONS = 10; 5         // 定义变量存放正确的个数，定义变量存放循环次数 6         int correctCount = 0; 7         int count = 1; 8         // 定义开始时间 9         long startTime = System.currentTimeMillis();10         // 创建一个输入对象11         java.util.Scanner input = new java.util.Scanner(System.in);12         // 随机产生两个整数，循环10次13         while (count <= 10) {14             // 定义两个整数变量，存放随机产生的1~15内的整数15             int num1 = (int) (Math.random() * 15) + 1;16             int num2 = (int) (Math.random() * 15) + 1;17             // 输入答案18             System.out.print("What is " + num1 + " + " + num2 + "? ");19             int answer = input.nextInt();20             // 如果回答正确，正确的个数加一，回答不正确，输出正确的结果21             if (num1 + num2 == answer) {22                 System.out.println("You are correct!");23                 correctCount++;24             } else25                 System.out.println("Your answer is wrong.\n" + num1 + " + "26                         + num2 + " should be " + (num1 + num2));27             // 循环次数加一28             count++;29         }30         // 定义结束时间31         long endTime = System.currentTimeMillis();32         // 计算测验时间33         long testTime = endTime - startTime;34         // 输出正确答案的个数与测验时间（单位秒）35         System.out.println("Correct count is " + correctCount36                 + "\nTest time is " + testTime / 1000 + " seconds");37     }38 }