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());
}
}
}