public class test_1 {

?? ?public static void main(String[] args) {
?? ??? ?test_1 result = new test_1();
?? ??? ?result.deal2();
?? ?}
?? ?public class DIYException1 extends Exception {
?? ??? ?public DIYException1() {
?? ??? ?}
?? ?}
?? ?public class DIYException2 extends Exception {
?? ??? ?public DIYException2() {
?? ??? ?}
?? ?}
?? ?//自定義兩種異常
?? ?public void test() throws DIYException1 {
?? ??? ?throw new DIYException1();
?? ?}
?? ?//通過test()，拋出異常1
?? ?public void deal1() throws DIYException2 {
?? ??? ?try {
?? ??? ??? ?test();
?? ??? ?} catch (DIYException1 e) {
?? ??? ??? ?System.out.println("error1");
?? ??? ??? ?throw new DIYException2();
?? ??? ?}?? ?
?? ?}
?? ?//檢測到異常1拋出后，拋出異常2，并輸出error1
?? ?public void deal2() {
?? ??? ?try {
?? ??? ??? ?deal1();
?? ??? ?} catch (DIYException2 e) {
?? ??? ??? ?System.out.println("error2");
?? ??? ?}
?? ?}
?? ?//檢測到異常2后，輸出error2
}

.initCause()是Exception中封裝好的一些方法

newExc.initCause(e);是用來干什么的？

新的RuntimeException就叫做newExc,文中有定義：RuntimeException newExc=new RuntimeException,新的newExc是用來接收上個文件傳進來的異常的.