Java学习---异常处理

import java.util.Scanner;

public class MyExceptionTest {
    
    public static void check(Square A) throws WrongException
    {
        if(A.getChang()<=0 && A.getKuan()<=0){
            throw new WrongException("长<=0,不合法, 宽<=0,也不合法");
        }
        if(A.getKuan()<=0){
            throw new WrongException("宽<=0,不合法");
        }
        if(A.getChang()<=0){
            throw new WrongException("长<=0,不合法");
        }
        A.CalcuArea();
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Square A=new Square();
        Scanner in =new Scanner(System.in);
        System.out.println("请输入矩形参数:\n"+"长： 宽：\n");
        int Chang=in.nextInt();
        A.setChang(Chang);
        int kuan=in.nextInt();
        A.setKuan(kuan);
        
        try{        
            check(A);
            System.out.println(A.toString());
        }catch(WrongException e){
            System.out.println("报错啦\n"+e.getMessage());
            e.toString();
            e.printStackTrace();            
        }finally{
            System.out.println("谢谢使用，再见！");
        }
    }
}

class Square
{    
    private int Chang,Kuan;
    private int Area;

    public int getChang() {
        return Chang;
    }
    public String toString() {
        return "矩形  [长=" + Chang + ", 宽=" + Kuan + ", 面积=" + Area + "]";
    }

    public void setChang(int chang) {
        Chang = chang;
    }

    public int getKuan() {
        return Kuan;
    }

    public void setKuan(int kuan) {
        Kuan = kuan;
    }
    public void CalcuArea()
    {
        Area=Chang*Kuan;
    }
}

class WrongException extends Exception {
    
    //定义一个Message
    String Message;
    
    //构造方法,设置Message
    public WrongException(String Message) {
        this.Message = Message;
    }
    
    //输出Message
    public String getMessage()
    {
        return Message;
    }
}

public class Test1 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a = 100, b = 0, c;
        try{
            c = a / b;
            System.out.println("c=" + c);
        }catch(ArithmeticException e){
            System.out.println("catched!");
            System.out.println("catch ArithmeticException message:"+
            e.getMessage());
            System.out.println("catch ArithmeticException toSting():"
                    + e.toString());
            e.printStackTrace();//打印出现错误的地方
        }finally{
            System.out.println("finally!");
        }
    }

}

public class Test4 {

    public static void main(String[] args) {
        int a = 100, b = 2, c = 0;
        int[] x = { 10, 20, 30, 40, 50, 60, 70 };
        // 如果try写在for循环外面，异常后就跳出，将不再进入循环
        for (int i = 0; i <= 10; i++) {
            System.out.println("c=" + c);
            try {
                c = a / b--;
                System.out.println("x[" + i + "]=" + x[i]);
            } catch (ArithmeticException e) {
                System.out.println("catched ArithmeticException message:" + e.getMessage());
                System.out.println("catched ArithmeticException toSting():" + e.toString());
                e.printStackTrace();
            } catch (ArrayIndexOutOfBoundsException e) {
                System.out.println("catched ArrayIndexOutOfBoundsException!");
            } finally {
                System.out.println("finally!");
            }
        }
    }

}

c=0
x[0]=10
finally!
c=50
x[1]=20
finally!
c=100
catched ArithmeticException message:/ by zero
catched ArithmeticException toSting():java.lang.ArithmeticException: / by zero
java.lang.ArithmeticException: / by zero
    at Test4.main(Test4.java:11)
finally!
c=100
x[3]=40
finally!
c=-100
x[4]=50
finally!
c=-50
x[5]=60
finally!
c=-33
x[6]=70
finally!
c=-25
catched ArrayIndexOutOfBoundsException!
finally!
c=-20
catched ArrayIndexOutOfBoundsException!
finally!
c=-16
catched ArrayIndexOutOfBoundsException!
finally!
c=-14
catched ArrayIndexOutOfBoundsException!
finally!

//使用 throw 语句抛出异常、使用 throws 子句抛弃异常
public class TestThrow1 {
    static void throwProcess(Object o) throws NullPointerException{// throws NullPointerException可不写
        if(o==null){
            throw new NullPointerException("空指针异常");//手动写抛出异常
        }
        //若抛出异常则不再执行函数下面的语句
        System.out.println(o+"哈哈呵呵");
    }
    public static void main(String[] args) {
        Object p=null;
        try{
            throwProcess(p);
        }catch(NullPointerException e){
            System.out.println("捕获：" + e);
        }
    }

}