java 比较字符串，捕获异常

代码实现：

public class BallanceNotEnoughException extends Exception  { 
	//无参的构造方法
	public BallanceNotEnoughException(){}
	//有参的构造方法，参数为异常中的消息
	public BallanceNotEnoughException(String message){
		super(message);
	}
}

测试类代码实现：

//比较字符串比较异常
public class NullPoniterExceptionTest {

	public static void main(String[] args) {
		try {
			compare(null, "asfa");
		} catch (NullPointerException e) {
			System.out.println("发生异常了！！！！");
		}
	}
	static boolean compare(String a, String b) throws NullPointerException {
		if (a == null || b == null)  {
			throw new NullPointerException();
		}
		return a.equals(b);
	}
}

效果类实现：