简单代码_循环_20160910

最新推荐文章于 2021-05-22 03:46:18 发布

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本文提供了一个Java程序示例，演示了如何使用循环结构（包括while和do-while循环）进行数值累加，并通过一个质数检测方法展示了如何找出前50个质数。该示例适用于Java初学者理解循环和条件判断的基本用法。

package Chapter04;

public class chapter04_example01 {

    public static void main(String[] args) {
        //第四章 循环
        //cyclemethods();
        primeNumber();
    }

    public static void cyclemethods(){
        //
        int number1 = 10, sum1 = 0, sum2 = 0;
        while (number1 >= 0) {
            sum1 += number1;
            number1--;
        }
        System.out.println("sum1 = " + sum1);
        number1 = 0;
        do {
            sum2 += number1;
            System.out.print(number1 + "\t");
            number1++;
        } while (number1 <= 10);
        System.out.println("\nsum2 = " + sum2);
    }

    public static void primeNumber(){
        final int numberofprime = 50;
        final int numberofpreline = 10;
        int count = 0, number1 = 2;
        System.out.println("the 50 primes is :");
        while (count < numberofprime){
            boolean isprime = true;
            for(int testprime = 2; testprime <= number1/2; testprime++){
                if(number1%testprime==0){
                    isprime = false;
                    break;
                }//if
            }//for
            if (isprime) {
                count++;
                if (count % numberofpreline == 0)
                    System.out.println(number1);// 换行
                else
                    System.out.print(number1 + " ");// 无需换行
            }
            number1++;
        }//while
    }
}