Java异常处理学习

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抛出一个异常

        throw new ArrayIndexOutOfBoundsException();        //手动抛出 2.JVM运行时帮你抛出

public class Launcher {    public static void main(String[] args){        m1();    }    public static void m1(){        m2();    }    public static void m2(){        int[] arr = new int[2];        arr[2] =1;    }}/*Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2at Launcher.m2(Launcher.java:13)at Launcher.m1(Launcher.java:9)at Launcher.main(Launcher.java:6)*/

public class Launcher {    public static void main(String[] args){        try{            m1();        }catch(ArrayIndexOutOfBoundsException e){            e.printStackTrace();        }catch(Exception e){            e.printStackTrace();        }finally{            System.out.println("finally");        }    }    public static void m1(){        m2();    }    public static void m2(){        int[] arr = new int[2];        arr[2] =1;    }}//catch可以有多个，顺序从小到大

自定义异常：

public class MyException extends Exception //继承自Exception{    public MyException(){        super();    }    public MyException(String msg){        super(msg);    }}    public static void main(String[] args)throws MyException{        throw new MyException("出现异常了");    //  throw new NullPointerException();    }

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