java上机练习 4.2

1.打印出所有的"水仙花数"，所谓"水仙花数"是指一个三位数，其各位数字立方和等于该数本身。例如：153是一个"水仙花数"，因为153=1的三次方＋5的三次方＋3的三次方。

package haha;

public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int a=0;
		int b=0;
		int c=0;
        for(int i=100;i<=999;i++){
        	int ge=i%10;
        	int shi=i/10%10;
            int bai=i/100;
        	if(ge*ge*ge+shi*shi*shi+bai*bai*bai==i)
        		   System.out.println(i);
           }
	}

}

　　

2.在控制台输出以下图形（知识点：循环语句、条件语句）

package haha;

import java.util.Scanner;
public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		        for(int i=1;i<7;i++) {
		            for(int j=1;j<=i;j++) {
		                System.out.print(j);
		            }
		            System.out.println();
		        }
	}

}

　　

package haha;

import java.util.Scanner;
public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		for(int i=1;i<7;i++) {
            for(int j=1;j<=7-i;j++) {
                System.out.print(j);
            }
            System.out.println();
        }        
	}

}

　　

package haha;

import java.util.Scanner;
public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		for(int i=1;i<7;i++) {
            for(int j=i;j>0;j--) {
                System.out.print(j);
            }
            System.out.println();
        }
	}

}

　　

package haha;

import java.util.Scanner;
public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		for(int i=6;i>0;i--) {
            for(int k=0;k<6-i;k++) {
                System.out.print(" ");
            }
            for(int j=1;j<=i;j++) {
                System.out.print(j);
            }
            System.out.println("");
        }
	}

}

　　

3.输入年月日，判断这是这一年中的第几天

package haha;

import java.util.Scanner;
public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int x = 0;
        Scanner sc=new Scanner(System.in);
        System.out.print("请输入年份");
        int year=sc.nextInt();
        System.out.print("请输入月份");
        int month=sc.nextInt();
        System.out.print("请输入日期");
        int date= sc.nextInt();
        if(year%4==0 && year%100!=0 || year%400==0) {
            switch(month) {
            case 1:  x=31; break;
            case 2:  x=31+29;break;
            case 3:  x=31+29+31;break;
            case 4:  x=31+29+31+30;break;
            case 5:  x=31+29+31+30+31;break;
            case 6:  x=31+29+31+30+31+30;break;
            case 7:  x=31+29+31+30+31+30+31;break;
            case 8:  x=31+29+31+30+31+30+31+31;break;
            case 9:  x=31+29+31+30+31+30+31+31+30;break;
            case 10: x=31+29+31+30+31+30+31+31+30+31;break;
            case 11: x=31+29+31+30+31+30+31+31+30+31+30;break;
            case 12: x=31+29+31+30+31+30+31+31+30+31+30+31;break;
            }
        }else {
            switch(month) {
            case 1:  x=31;break;
            case 2:  x=31+28;break;
            case 3:  x=31+28+31;break;
            case 4:  x=31+28+31+30;break;
            case 5:  x=31+28+31+30+31;break;
            case 6:  x=31+28+31+30+31+30;break;
            case 7:  x=31+28+31+30+31+30+31;break;
            case 8:  x=31+28+31+30+31+30+31+31;break;
            case 9:  x=31+28+31+30+31+30+31+31+30;break;
            case 10: x=31+28+31+30+31+30+31+31+30+31;break;
            case 11: x=31+28+31+30+31+30+31+31+30+31+30;break;
            case 12: x=31+28+31+30+31+30+31+31+30+31+30+31;break;
            }
        }
        System.out.println(year+"年"+month+"月"+date+"日"+"是第"+(x+date)+"天"); 
	}
	}

　　

4.由控制台输入一个4位整数，求将该数反转以后的数，如原数为1234，反转后的数位4321

package haha;

import java.util.Scanner;
public class heihei {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
	     int i = sc.nextInt();
	     if(i>=1000&&i<10000){
	      int ge = i%10;
	      int shi = i%100/10;
	      int bai = i%1000/100;
	      int qian = i/1000;
	      int sum = qian+bai*10+shi*100+ge*1000;
	      System.out.println(sum);
	     }else{
	      System.out.println("ERROR!");
	     }
	}

}