问题： 如何抛出一个系统异常并且捕获它
代码如下：
public class ThrowDemo {
static void demoproc() {
try {
throw new NullPointerException("demo");
} catch (NullPointerException e) {
System.out.println("Caught inside demoproc.");
throw e; // rethrow the exception
}
}
public static void main(String args[]) {
try {
demoproc();
} catch (NullPointerException e) {
System.out.println("Recaught: " + e);
}
}
}运行结果：
Caught inside demoproc.
Recaught: java.lang.NullPointerException: demo