throw和throws | 陌名如初

throw

throw的作用

• 如果Java虚拟机不能判断异常e，可以生成异常对象e，用throw加上这个异常对象抛出这个异常。
  示例：

  package src;
  class People{
    private int age;
    public void setAge(int age){
        if(age < 0){
            RuntimeException e = new RuntimeException("年龄不能为负数");
            throw e;
        }
        this.age = age;
        System.out.println(age);
    }
  }
  class Test{
    public static void main(String args[]){
        People people = new People();
        people.setAge(-20);
    }
  }

运行结果：

throws

throws

• 声明一个函数可能产生异常，函数不对异常进行处理，在调用函数的地方对异常进行处理。
  示例：

  package src1;
  class People{
    private int age;
    public void setAge(int age)  throws Exception{
        if(age < 0){
            Exception e = new Exception("年龄不能为负数");
            throw e;
        }
        this.age = age;
        System.out.println(age);
    }
  }
  class Test{
    public static void main(String args[]){
        People people = new People();
        try{
            people.setAge(-20);
        }
        catch(Exception e){
            System.out.println(e);
        }
    }
  }

  运行结果：
  

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