Java异常处理实例详解

class TestTryCatch {
 public static void main(String[] args){
  int arr[] = new int[5];
  arr[7] = 10;
  System.out.println("end!!!");
 }
}

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 7
	at TestTryCatch.main(TestTryCatch.java:4)

进程已结束,退出代码1

class TestTryCatch {
 public static void main(String[] args){
  try {
   int arr[] = new int[5];
   arr[7] = 10;
  }
  catch (ArrayIndexOutOfBoundsException e){
   System.out.println("数组范围越界！");
   System.out.println("异常："+e);
  }
  finally {
   System.out.println("一定会执行finally语句块");
  }
  System.out.println("end!!!");
 }
}

数组范围越界！
异常：java.lang.ArrayIndexOutOfBoundsException: 7
一定会执行finally语句块
end!!!

int a = 5, b = 0;
try{
 if(b == 0)
  throw new ArithmeticException("一个算术异常，除数0");
 else
  System.out.println(a+"/"+b+"="+ a/b);
}
catch(ArithmeticException e){
 System.out.println("抛出异常："+e);
}

抛出异常：java.lang.ArithmeticException: 一个算术异常，除数0

void add(int a, int b) throws Exception {
  int c = a/b;
  System.out.println(a+"/"+b+"="+c);
 }

TestTryCatch obj = new TestTryCatch();
obj.add(4, 0);

java: 未报告的异常错误java.lang.Exception; 必须对其进行捕获或声明以便抛出

TestTryCatch obj = new TestTryCatch();
try{
 obj.add(4, 0);
}
catch (Exception e){
 System.out.println("必须处理异常："+e);
}

必须处理异常：java.lang.ArithmeticException: / by zero

class 异常类名 extends Exception{
	......
}

class MyException extends Exception{
 public MyException(String msg){
  // 调用 Exception 类的构造方法，存入异常信息
  super(msg);
 }
}

try{
 throw new MyException("自定义异常！");
}
catch (Exception e){
 System.out.println(e);
}

MyException: 自定义异常！