java 异常处理

Posted 2021-01-26 fitzroy343

参考:

海伦公式

• 

开根号 Math.sqrt

java利用异常处理输入格式

String类的split方法

java控制小数输出

mport java.util.*;

public class test {
    public static void main(String[] args){
        try {
            Scanner sc = new Scanner(System.in);
            System.out.println("请输入加法加法表达式，格式为:21+12+31");
            String s = sc.nextLine();
            String[] num = s.split("\\+");
            int num_1 = Integer.parseInt(num[0]);
            int num_2 = Integer.parseInt(num[1]);
            int num_3 = Integer.parseInt(num[2]);
            int result = num_1+num_2+num_3;
            System.out.println(num_1 + "+" + num_2 + "+" + num_3 + "=" +result);
        }catch(Exception e) {
            System.out.println("Input Error!!");
        }
    }
}

 

 

public class Triangle {
    double a;
    double b;
    double c;

    public Triangle( double a, double b, double c ){
        this.a = a;
        this.b = b;
        this.c = c;
    }

    void isTriangle() throws MyException{
        if( a+b<=c || a+c<=b || b+c<=a ){
            throw new MyException("无法构成三角形，两边之和小于第三边");
        }
        else{
            System.out.println("构成三角形");
        }
    }

    public static void main(String[] args){
        Triangle t = new Triangle(2,2,5);
        try{
            t.isTriangle();
        }catch(MyException e){
            System.out.println(e.getMessage());
        }catch(Exception e){
            System.out.println("程序发生了其他的异常");
        }
    }
}

class MyException extends Exception{
    String message;

    public MyException(String ErrorMessage){
        message = ErrorMessage;
    }

    public String getMessage(){
        return message;
    }

}

 

 

 

import java.lang.Math;
import java.util.*;


abstract class Shape{
    abstract protected void getArea();
}

class triangle extends Shape{
    double a;
    double b;
    double c;

    triangle(double a, double b, double c){
        this.a = a;
        this.b = b;
        this.c = c;
    }

    public void getArea(){
        double p = a+b+c/2;
        System.out.println("三角形面积:" +String.format("%.2f",Math.sqrt(p*(p-a)*(p-b)*(p-c))));
    }
}

class circle extends Shape{
    double r;

    circle(double r){
        this.r = r;
    }

    public void getArea(){
        System.out.println("圆形面积:"+String.format("%.2f",Math.PI*r*r));
    }
}

class rectangle extends Shape{
    double x;
    double y;

    rectangle( double x, double y ){
        this.x = x;
        this.y = y;
    }

    public void getArea(){
        System.out.println("矩形面积:"+String.format("%.2f",x*y));
    }
}

class mException extends Exception{
    String message;

    public mException(String ErrorMessage){
        message = ErrorMessage;
    }

    public String getMessage(){
        return message;
    }

}


public class Test_3 {
    triangle t = new triangle(3,4,5);
    rectangle r = new rectangle(3,4);
    circle c = new circle(5);

    void cmd(String s) throws mException{
        if( s.equals("1") || s.equals("2") || s.equals("3") ) {
            switch (s) {
                case "1":
                    c.getArea();
                    break;
                case "2":
                    r.getArea();
                    break;
                case "3":
                    t.getArea();
                    break;
            }
        }
        else{
            System.out.println("输入错误");
        }
    }

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        Test_3 t = new Test_3();

        try{
            t.cmd(s);
        }catch(mException e){
            System.out.println(e.getMessage());
        }catch(Exception e){
            System.out.println("程序其他错误");
        }
    }

}