java中一个方法怎么抛出三种错误并用一个catch捕获三种错误

public class CatchMultiException {    public static void main(String[] args) throws Exception {        try {            test(2);        } catch (Exception e) {            if (e instanceof TestAException || e instanceof TestBException                    || e instanceof TestCException) {                e.printStackTrace();            } else {                throw e;            }        }    }    public static void test(int a) throws TestAException, TestBException,            TestCException {        if (a == 0) {            throw new TestAException();        }        if (a == 1) {            throw new TestBException();        }        if (a == 2) {            throw new TestCException();        }    }}class TestAException extends Exception {    private static final long serialVersionUID = 1L;}class TestBException extends Exception {    private static final long serialVersionUID = 1L;}class TestCException extends Exception {    private static final long serialVersionUID = 1L;}
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探讨

java编程思想这本书上的一道练习题，题目是：定义三种新的异常类型，写一个类，在一个方法中抛出三种异常，在main中调用这个方法，仅用一个catch捕获三个异常