自定义异常(一)

package cn.exp;
//自定义异常继承自Exception
//注意throw和throw的区别
class ExceTest extends Exception {
	private String errorMessage;

	public ExceTest(String errorMessage) {
		this.errorMessage = errorMessage;
	}

	public String showMessage() {
		return errorMessage;
	}
}

class TestClass {//注意throw和throw的区别
	public void show(int a, int b) throws ExceTest {
		if (b < 0)
			throw new ExceTest("参数错误");
		System.out.println("参数正确；若出错，此句便不会输出");
	}
}

public class ExceptionDemo1 {
	public static void main(String[] args){
            TestClass testClass=new TestClass();
            try {
		testClass.show(3, -4);
	} catch (ExceTest e) {
	         System.out.println(e.showMessage());
		}
	}
}