day35 捕获和抛出异常

异常处理机制

• 抛出异常

• 捕获异常

• 异常处理五个关键字

  • try、catch、finally、throw、throws

例：

package com.exception;

public class Test2 {
    public static void main(String[] args) {

        int a = 1;
        int b = 0;

        //Ctrl+Alt+T
        try {
            System.out.println(a/b);
        } catch (Exception e) {
            System.exit(1);
            e.printStackTrace();//打印错误的栈信息
        } finally {
        }
    }
}

package com.exception;

public class Test {
    public static void main(String[] args) {
        try {
            new Test().test(1,0);
        } catch (ArithmeticException e) {
            e.printStackTrace();
        } finally {
        }
    }

    //假设这方法中，处理不了这个异常，方法上抛出异常
    public void test(int a,int b) throws ArithmeticException{
        if (b == 0){
            throw new ArithmeticException();//主动抛出异常，一般在方法中使用
        }
        System.out.println(a/b);
    }

}


/*
 int a = 1;
        int b = 0;

        //假设要捕获多个异常：从小到大哦

        try {   //try监控区域

            if (b == 0){//    throw   throws
                throw new ArithmeticException();//主动抛出异常
            }
            //new Test().a();
            System.out.println(a/b);
        }catch (Error e){ //catch (想要捕获的异常类型) 捕获异常
            System.out.println("Error");
        }
        catch (Exception e){
            System.out.println("Exception");
        }
        catch (Throwable t){
            System.out.println("Throwable");
        }finally {
            System.out.println("finally");
        }

        //finally 可以不要finally，假设IO，资源，关闭

    }

    public void a(){
        b();
    }
    public void b(){
        a();
    }
 */