JAVA编程基础：分支与循环结构详解-优快云博客

本文链接：https://blog.youkuaiyun.com/Dream_C_H/article/details/109035177

这篇博客详细介绍了JAVA编程中的分支结构，包括if条件语句、if...else语句和switch...case的使用。同时，讲解了循环结构，如do...while、while和for循环，并给出了随机加法运算和九九乘法表的例子。此外，还探讨了数组的遍历、排序、复制和找最大值的操作，以及方法的实例应用。

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JAVA编程实例2

一.分支结构
二.循环结构
三.数组演示
三.方法的演示
- 1.方法实例

一.分支结构

1.if条件语句

代码如下：

package day03;
public class ifDemo {
	public static void main(String[] args) {
int num =9;
		if(num%2==0){
			System.out.println(num+"为偶数");
		}
		System.out.println("over");
		double price = 700;
		if(price>500){
			price *=0.8;
		}
		System.out.println("最终金额为"+price);
	}

}

2.if…else条件语句

代码如下：

package day03;
public class ifElseDemo {
	public static void main(String[] args) {
int number =5;
		if(number%2==0){
			System.out.println(number+"是偶数");
		}else{
			System.out.println(number+"是奇数");
		}
		double price=600;
		if(price>=500){
			price *= 0.8;
		}else{
			price *= 0.9;
		}
		System.out.println("最终金额为"+price);
    }
}

3.switch…case

package day04;
//命令解析程序
import java.util.Scanner;
public class CommandBySwitch {
	public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
		System.out.println("请选择功能：1.存款2.取款3.查询余额4.退卡");
		int command =scan.nextInt();
		switch(command){
			
		    case 1:
			    System.out.println("存款成功");
			    break;
		    case 2:
		    	System.out.println("取款成功");
		    	break;
		    case 3:
		    	System.out.println("查询余额");
		    	break;
		    case 4:
		    	System.out.println("退卡成功");
		    	break;
		    default:
		    	System.out.println("输入错误");
		}



    int year =2020;
	int month =3;
	int days = 0;
	switch(month){
	case 1:
	case 3:	
	case 5:
	case 7:
	case 8:	
	case 10:	
	case 12:
		days=31;
		break;
	case 4:	
	case 6:
	case 9:	
	case 11:
		days=30;
		break;
	case 2:	
		if(year%4==0&&year%100!=0||year%400==0){
			days=29;
		}else{
			days=30;
		}		
	}
	System.out.println(year+"年"+month+"月有"+days+"天");
	}
}

二.循环结构

1.do…while

package day04;
import java.util.Scanner;
public class DoWhileDemo {
	public static void main(String[] args) {
		Scanner scan =new Scanner(System.in);
		int num=(int)(Math.random()*1000+1);
		int guess;
		do{
			System.out.println("猜吧");
			guess = scan.nextInt();
			if(guess<num){
				System.out.println("太小了");
			}else if(guess>num){
				System.out.println("太大了");
			}else{
				System.out.println("恭喜你猜对了");
			}
		}while(guess!=num);
	}
}

2.while

package day04;
import java.util.Scanner;
public class Addition {
	public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
		int num =300;
		System.out.println("猜吧");
		int guess = scan.nextInt();
		while(guess!=num){
			if(guess<num){
				System.out.println("太小了");
			}else{
				System.out.println("太大了");
			}
			System.out.println("猜吧");
			guess = scan.nextInt();
		}
		System.out.println("恭喜你猜对了");
		}
}

3.for循环

1）随机加法运算

package day05;
//随机加法运算
import java.util.Scanner;
public class Addition {
	public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
        int score=0,result;
		for(int i=1;i<=10;i++){
			int a=(int)(Math.random()*100);
			int b=(int)(Math.random()*100);
			result =a+b;
			System.out.println("("+i+")"+a+"+"+b+"=?");
			int answer =scan.nextInt();
			if(answer==-1){
				break;
			}
			if(answer==result){
				System.out.println("答对了");
				score +=10;
			}else{
				System.out.println("答错了");
			}
		}
		System.out.println("成绩为"+score);
		}
}

2）九九乘法表

package day05;
//99乘法表
public class MultiTable {
	public static void main(String[] args) {
       for(int i=1;i<=9;i++){
			for(int num=1;num<=i;num++){
				System.out.print(i+"*"+num+"="+i*num+"\t");
			}
			System.out.println();
		}
	}

}

三.数组演示

1.数组的遍寻

package day05;
//数组
public class ArrayDemo {
	public static void main(String[] args) {
        int[] arr=new int[10];
		for(int i=0;i<arr.length;i++){
			arr[i]=(int)(Math.random()*100);
			System.out.println(arr[i]);
		}
   }
}

package day05;
//数组
import java.util.Scanner;
public class ArrayDemo {
	public static void main(String[] args) {
		Scanner scan =new Scanner(System.in);
		
		double[] scores=new double[10];
		for(int i=0;i<scores.length;i++){
			System.out.println("请输入第"+(i+1)+"个学生的成绩");
			scores[i]=scan.nextDouble();
		}
		double total=0;
		for(int i=0;i<scores.length;i++){
			total +=scores[i];
		}
		double avg=total/scores.length;
		System.out.println("总分为"+total+"平均分为"+avg);
	}

}

2.数组的排序（升序）

package day06;
import java.util.Arrays;
public class ArrayDemo {
	public static void main(String[] args) {
	int[] arr=new int[10];
		for(int i=0;i<arr.length;i++){
			arr[i]=(int)(Math.random()*100);
			System.out.println(arr[i]);
		}
		Arrays.sort(arr);
		
		for(int i=0;i<arr.length;i++){
			System.out.println(arr[i]);
		}
	}
}

3.数组的复制

package day06;
import java.util.Arrays;
public class ArrayDemo {
	public static void main(String[] args) {
	int[] a={1,2,3,4,5};
		int[] b=new int[8];
		System.arraycopy(a,2,b,3,3);
		for(int i=0;i<b.length;i++){
			System.out.println(b[i]);
		}
	}
}

4.数组的最大值

package day06;
import java.util.Arrays;
public class MaxOfArray {

	public static void main(String[] args) {
		int[] arr=new int[10];
		for(int i=0;i<arr.length;i++){
			arr[i]=(int)(Math.random()*100);
			System.out.println(arr[i]);
		}
		int max=arr[0];
		for(int i=1;i<arr.length;i++){
			if(max<arr[i]){
				max=arr[i];
			}
		}
		arr=Arrays.copyOf(arr,arr.length+1);
		arr[arr.length-1]=max;
		for(int i=0;i<arr.length;i++){
			System.out.println(arr[i]);
		}
	}
}

三.方法的演示

1.方法实例

package day06;
public class Text {
	public static void main(String[] args) {
		say();
		sayhi("ch");
		sayhello("ch",24);
		double a=getnum();
		System.out.println(a);
		int b=plus(5,6);
		System.out.println(b);
		double[] c=array();
		for(int i=0;i<c.length;i++){
			System.out.println(c[i]);
		}
	}
	public static void say(){
		System.out.println("我叫ch，今年24");
	}
	public static void sayhi(String name){
		System.out.println("我叫"+name+"，今年24");
	}
	public static void sayhello(String name,int age){
		System.out.println("我叫"+name+"，今年"+age);
	}
	public static double getnum(){
		return 3.14;
	}
	public static int plus(int num1,int num2){
		int num =num1+num2;
		return num;
	}
	public static double[] array(){
		double[] a={0,3.14,5.26};
		return a;
	}
}