如何在Java中抛出一般异常？ [英] How to throw a general exception in Java?

问题描述

考虑这个简单的程序。该程序有两个文件：

  Vehicle.java：
 
 
 class Vehicle {
 private int speed = 0; 
 private int maxSpeed = 100; 
 
 public int getSpeed（）
 {
 return speed; 
} 
 
 public int getMaxSpeed（）
 {
 return maxSpeed; 
} 
 
 public void speedUp（int increment）
 {
 if（speed + increment> maxSpeed）{
 // throw exception 
} else {
 speed + = increment; 
} 
} 
 
 public void speedDown（int decrement）
 {
 if（speed-decrement< 0）{
 //抛出异常
} else {
 speed  -  = decrement; 
} 
} 
} 
  

HelloWorld.java： / p>

  public class HelloWorld {
 
 / ** 
 * @param args 
 * / 
 public static void main（String [] args）{
 
 Vehicle v1 = new Vehicle（）; 
 Vehicle v2 = new Vehicle（）; 
 
 //做某事
 
 //打印有用的东西，TODO 
 System.out.println（v1.getSpeed（））; 
} 
 
} 
  

正如你可以看到第一个我已经添加了一个注释（// throw exception），我想抛出一个异常。我必须定义我自己的类的异常，还是在Java中有一些一般的异常类可以使用？

解决方案

你可以创建自己的异常类：

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

在你的代码中：

  throw new InvalidSpeedException（TOO HIGH）; 
  

Consider this simple program. The program has two files:

Vehicle.java:


class Vehicle {
    private int speed = 0;
    private int maxSpeed = 100;

    public int getSpeed()
    {
        return speed;
    }

    public int getMaxSpeed()
    {
        return maxSpeed;
    }

    public void speedUp(int increment)
    {
        if(speed + increment > maxSpeed){
            // throw exception
        }else{
            speed += increment;
        }
    }

    public void speedDown(int decrement)
    {
        if(speed - decrement < 0){
            // throw exception
        }else{
            speed -= decrement;
        }
    }
}

And HelloWorld.java:

public class HelloWorld {

    /**
     * @param args
     */
    public static void main(String[] args) {

        Vehicle v1 = new Vehicle();
        Vehicle v2 = new Vehicle();

            // do something

            // print something useful, TODO         
        System.out.println(v1.getSpeed());
    }

}

As you can see in the first class, I have added a comment ("// throw exception") where I would like to throw an exception. Do I have to define my own class for exceptions or is there some general exception class in Java I can use?

解决方案

You could create your own Exception class:

public class InvalidSpeedException extends Exception {

  public InvalidSpeedException(String message){
     super(message);
  }

}

In your code:

throw new InvalidSpeedException("TOO HIGH");

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