Java经典案例代码(持续更新中...)

        2024/11/4

目录

一、找素数

①方法一

②方法二

二、打印九九乘法表

三、打印三角形

四、双色球系统

一、找素数

①方法一

public class Test07 {
    public static void main(String[] args) {
        System.out.println(Find(101, 200));
    }
public static int Find(int start,int end){
        int count = 0;
        for(int i = start;i <= end;i++){
            boolean flag = true;
            for(int j = 2;j <= i / 2;j++){
                if(i % j == 0){
                    flag = false;
                    break;
                }
            }
            if(flag){
                System.out.println(i);
                count++;
            }
        }
        return count;
}
}

②方法二

public class Test07_2 {
    public static void main(String[] args) {
        int count = 0;
        OUT://为外部循环指定标签
        for(int i = 101;i <= 200;i++){
            for(int j = 2;j <= i / 2;j++){
                if(i % j == 0){
                    continue OUT;
                }
            }
            count++;
            System.out.println(i);
        }
        System.out.println(count);
    }
}

二、打印九九乘法表

public class Test08 {
    public static void main(String[] args) {
        for(int i = 1;i <= 9;i++){
            for(int j = 1;j <= i;j++){
                System.out.print(j + "X" + i + "=" + (j * i) + "\t");
            }
            System.out.println();
        }
    }
}

三、打印三角形

public class Test09 {
    public static void main(String[] args) {
//           *
//          ***
//         *****
//        *******
//        行（i）      空格（n-i）       星星（2i -1）
//           1        3                   1
//           2        2                   3
//           3        1                   5
//           4        0                   7
        int n = 4;
        for(int i = 1;i <= 4;i++){
            for(int j = 1;j <= (n-i);j++){
                System.out.print(" ");
            }
            for(int k = 1;k <=(2*i - 1);k++){
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

四、双色球系统

import java.util.Random;
import java.util.Scanner;

public class Test10 {
    public static void main(String[] args) {
        int[] userNumbers = userSelectNumbers();
        int[] luckyNumbers = createLuckyNumbers();
        Judge2(userNumbers,luckyNumbers);
    }

    public static int[] userSelectNumbers(){
        int[] nums = new int[7];
        Scanner sc = new Scanner(System.in);
        for(int i = 0;i < nums.length - 1;i++){
            while (true) {
                System.out.println("请输入第" + (i + 1) + "个红球号码");
                int num = sc.nextInt();
                if(num < 1 || num > 33){
                    System.out.println("您输入的号码有误！请重新输入");
                }else{
                    if(Judge1(nums,num)){
                        System.out.println("您输入的号码重复，请重新输入");
                    }else{
                        nums[i] = num;
                        break;
                    }
                }
            }
        }
        while (true) {
            System.out.println("请输入最后一个蓝球号码");
            int num = sc.nextInt();
            if(num < 1 || num > 16){
                System.out.println("您输入有误，请重新输入");
            }else{
                nums[nums.length - 1] = num;
                break;
            }
        }
        return nums;
    }


    public static boolean Judge1(int[] nums, int num) {
        for (int i = 0; i < nums.length; i++) {
            if(nums[i] == num){
                return true;
            }
        }
        return false;
    }


    public static int[] createLuckyNumbers(){
        int[] nums = new int[7];
        Random r = new Random();
        for(int i = 0;i < nums.length - 1;i++){
            while (true) {
                int num = r.nextInt(33) + 1;
                if(!Judge1(nums,num)){
                    nums[i] = num;
                    break;
                }
            }
        }
        int num = r.nextInt(17) + 1;
        nums[nums.length - 1] = num;
        return nums;
    }


    public static void Judge2(int[] userNumbers,int[] luckyNumbers){
        int redCount = 0;
        int blueCount = 0;
        for(int i = 0;i < userNumbers.length - 1;i++){
            for(int j = 0;j < luckyNumbers.length - 1;j++){
                if(userNumbers[i] == luckyNumbers[j]){
                    redCount++;
                    break;
                }
            }
        }

        blueCount = userNumbers[6] == luckyNumbers[6] ? 1 : 0;

        if(redCount == 6 && blueCount ==1){
            System.out.println("中1000万");
        }else if(redCount == 6 && blueCount ==0){
            System.out.println("中500万");
        }else if(redCount == 5 && blueCount ==1){
            System.out.println("中3000");
        }else if(redCount == 5 && blueCount ==0){
            System.out.println("中200");
        }else if(redCount == 4 && blueCount ==1){
            System.out.println("中200");
        }else if(redCount == 4 && blueCount ==0){
            System.out.println("中10");
        }else if(redCount == 3 && blueCount ==1){
            System.out.println("中10");
        }else if(redCount == 2 && blueCount ==1){
            System.out.println("中5");
        }else if(redCount == 1 && blueCount ==1){
            System.out.println("中5");
        }else if(redCount == 0 && blueCount ==1){
            System.out.println("中5");
        }else{
            System.out.println("没中");
        }
    }
}