java7里的multi-catch...半吊子的语法糖

public class Main {

	public static class A extends RuntimeException{}
	public static class B extends RuntimeException{}
	public static void throwRuntimeException(){
		if(Math.random()>=Math.random()){
			throw new A();
		}else{
			throw new B();
		}
	}
	public static void use(A a){}
	public static void use(B b){}
	
	public static void main(String[] args) {
		try{
			throwRuntimeException();
		}catch (A e) {
			use(e);
		}catch (B e) {
			use(e);
		}//ok
		try{
			throwRuntimeException();
		}catch (A|B e) {
			use(e);
		}//编译不通过,找不到use(RuntimeException);multicatch导致类型退化.这块糖我吃不起
	}
}