Java子类抛出的异常类型不能比父类抛出的异常类型更宽泛

  Java子类抛出的异常类型不能比父类抛出的异常类型更宽泛,只对非检查异常有效。

  如下的例子会报错，Exception为受查异常。

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

class ParentException extends Exception {
    public ParentException(String message){
        super(message);
    }
}

class ChildrenException extends Exception {
    public ChildrenException(String message){
        super(message);
    }
}

class Parent{
    public void sayHello()throws ChildrenException{
        System.out.println("Hi");
        throw new ChildrenException("这样下去不行不行");
    }
}

class Children extends Parent{
    public void sayHello()throws ParentException{
        System.out.println("Hi");
        throw new ParentException("这样下去不行不行");
    }
}

public class a{
    public static void main(String[] args)  {
        Parent parent = new Parent();
        Children children = new Children();
        parent.sayHello();
        children.sayHello();
    }
}

  如下的例子不会报错，RuntimeException为非受查异常

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

class ParentException extends RuntimeException {
    public ParentException(String message){
        super(message);
    }
}

class ChildrenException extends RuntimeException {
    public ChildrenException(String message){
        super(message);
    }
}

class Parent{
    public void sayHello()throws ChildrenException{
        System.out.println("Hi");
        throw new ChildrenException("这样下去不行不行");
    }
}

class Children extends Parent{
    public void sayHello()throws ParentException{
        System.out.println("Hi");
        throw new ParentException("这样下去不行不行");
    }
}

public class a{
    public static void main(String[] args)  {
        Parent parent = new Parent();
        Children children = new Children();
        parent.sayHello();
        children.sayHello();
    }
}