Java如何创建自定义异常来限制HashMap的大小

Question

我有一个将新项目插入到HashMap的方法，我想通过抛出异常来限制HashMap的大小HashMap 的大小大于特定值，例如 100，下面是我的实现:

public void addToHashMap(String id, Object value) throws HashMapOutOfBoundException{
    hashMap.put(id,value);    
}

private class HashMapOutOfBoundException extends Exception{
    //what should I do inside this class?
}

Answer 1

为什么不简单一点:

public void addToHashMap(String id, Object value) {
    if (hashMap.size()+1 > MAX_SIZE)
      throw new HashMapOutOfBoundException();
    hashMap.put(id,value);    
}

与

public class HashMapOutOfBoundException extends RuntimeException {}

来自javadoc:

RuntimeException and its subclasses are unchecked exceptions. Unchecked exceptions do not need to be declared in a method or constructor's throws clause if they can be thrown by the execution of the method or constructor and propagate outside the method or constructor boundary.