简单程序

摄氏度转换为华氏度并弹窗提示###

import java.util.Scanner;

import javax.swing.JOptionPane;

public class Temperature {
	public static void main(String[] args) {	
		String a = JOptionPane.showInputDialog("请输入摄氏度：");
		double b = Double.parseDouble(a);
		double c = b * 33.8;
		JOptionPane.showMessageDialog(null,"华氏度："+c);
	}
}

输出3个数内最大的数###

import javax.swing.JOptionPane;
public class FindMaxDig {
	
		public static void main(String[] args) {
			String a=JOptionPane.showInputDialog("请输入第一个数");
			String b=JOptionPane.showInputDialog("请输入第二个数");
			String c=JOptionPane.showInputDialog("请输入第三个数");
			int num1=Integer.parseInt(a);
			int num2=Integer.parseInt(b);
			int num3=Integer.parseInt(c);
			int max = num1>num2?num1:num2;
			max= max>num3?max:num3;
			JOptionPane.showMessageDialog(null, "最大数值为："+max);
		}		
}

三个数从小到大排序###

import java.util.Scanner;

public class Rank {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.print("请输入三个数字：");
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		if(a>b){
			int d = a;
			a=b;
			b=d;
		}
		if(a>c){
			int d = a;
			a=c;
			c=d;
		}
		if(b>c){
			int d = b;
			b=c;
			c=d;
		}
		
	System.out.println(a+"\t"+b+"\t"+c);
//System.out.printf("%d\t%d\t%d\n", a, b, c);
	sc.close();
	}

}

计算圆的周长与面积###

import java.util.Scanner;

public class Round {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("请输入圆的半径");
		final double pi = 3.14;
		int radii = sc.nextInt();
		double perimeter = (pi * 2) * radii;
		double area = pi * (radii * radii);
		System.out.println("圆的周长是：" + perimeter + "\n" + "圆的面积是：" + area);
		sc.close();
	}
}

自动输出今天天星期几早餐该吃什么###

package Hello;
//星期135吃包子，246吃油条，星期天吃面。
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Scanner;

public class Breakfast {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Calendar cal = new GregorianCalendar();
		int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
		if (dayOfWeek == 2) {
			System.out.println("今天星期一：");
		} else if (dayOfWeek == 3) {
			System.out.println("今天星期二：");
		} else if (dayOfWeek == 4) {
			System.out.println("今天星期三：");
		} else if (dayOfWeek == 5) {
			System.out.println("今天星期四：");
		} else if (dayOfWeek == 6) {
			System.out.println("今天星期五：");
		} else if (dayOfWeek == 7) {
			System.out.println("今天星期六：");
		} else {
			System.out.println("今天星期天：");
		}
		sc.close();
		switch (dayOfWeek) {
		case '2':
		case '3':
		case '4':
			System.out.print("今天早上吃包子");
			break;
		case '6':
			System.out.print("今天早上吃面");
			break;
		default:
			System.out.println("今天早上吃油条");
		}
	}
}