java  异常详解及应用实例

public class ExceptionDemo {

 public static void main(String[] args) {
 //OutOfMemoryError内存溢出错误，
 int[] i = new int[1024*1024*1024];
 System.out.println(i[1]);
 
 //ArrayIndexOutOfBoundsException索引越界异常
 int[] s = new int[2];
 System.out.println(s[2]);
 
 
 Calc calc = new Calc(); 
 //假如我们在这里捕获异常
 try {
  calc.run(4, 0);
  calc.run(4, -1);
 } catch (NegativeException e) {//必须先抛出异常的自定义子类
  e.printStackTrace();
  System.out.println(e.getMessage());
  //throw e;//可以继续将此异常抛出
 } catch (ArithmeticException e){//抛出自定义异常类的父类
  e.printStackTrace();
  System.out.println(e.getMessage());
  //throw e;
 } finally {
  System.out.println("finally肯定会执行到");
 }
 //如果上面进行了异常捕获，那么代码可以继续执行，否者代码不能继续执行
 System.out.println("可以执行到！");
 
 try {
  calc.run(4, -1);
  
 } catch (NegativeException e) {
  e.printStackTrace();
  System.out.println(e.getMessage());
  return;
 } finally {
  System.out.println("肯定会执行的");
 }
 System.out.println("执行不到了");//执行不到此行代码
 
 }

}

/**
 * 自定义异常
 */
class NegativeException extends ArithmeticException{
 public NegativeException() {
 }
 public NegativeException(String msg) {
 super(msg);
 }
}

interface AA{
 public abstract void method();
}

class Calc implements AA{
 //ArithmeticException其实为运行时异常(RuntimeException)，即使不进行throws声明，也可以通过编译
 public int run(int m,int n)throws ArithmeticException,NegativeException{
 if(n==0){
  throw new ArithmeticException("除数不能为0");
 }else if(n<0){
  throw new NegativeException("除数不能为负数");
 }
 int s = m/n;
 return s ;
 }

 @Override
 public void method() {
 try {
  int p = 4/0;
 } catch (ArithmeticException e) {
  e.printStackTrace();
  throw new RuntimeException();//将异常继续抛出为运行时异常
 }
 }
}