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());}}}