Java: catch a system signal

In Java, here is an example to catch a system signal:

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import sun.misc.Signal;
import sun.misc.SignalHandler;
import java.util.Random;

public class SignalTerm {

public static void main(String[] args) {

try{

System.out.println("System start.");
DiagSignalHandler.install("INT");
ThreadGroup tg = new ThreadGroup("AAA");
MyThread mt[] = new MyThread[10];
for(int i=0; i < mt.length; i++){

mt[i] = new MyThread(tg,i);
mt[i].start();

}
for(int i=0; i < mt.length; i++){

mt[i].join();

}
System.out.println("System exit.");

} catch(Exception e){

System.out.println("exception: " + e.getMessage());
e.printStackTrace();

}

}

}

class MyThread extends Thread {

private int threadcnt;
public MyThread(ThreadGroup tg, int n){

super(tg, "My" + n);
threadcnt = n;

}
public void run(){

try {

System.out.println("In thread " + threadcnt);
while(true) sleep(1000);

} catch (InterruptedException e) {

Random ran = new Random();
int rn = ran.nextInt(20);
System.out.println("Thread " + threadcnt + " is shuting down. Please wait " + rn + " seconds.");
try {

sleep(rn* 1000);

} catch (InterruptedException e1) {}
System.out.println("Thread " + threadcnt + " exit.");

}

}

}

//Diagnostic Signal Handler class definition
class DiagSignalHandler implements SignalHandler {

private SignalHandler oldHandler;

// Static method to install the signal handler
public static DiagSignalHandler install(String signalName) {

Signal diagSignal = new Signal(signalName);
DiagSignalHandler diagHandler = new DiagSignalHandler();
diagHandler.oldHandler = Signal.handle(diagSignal,diagHandler);
return diagHandler;

}

// Signal handler method
public void handle(Signal sig) {

System.out.println("Diagnostic Signal handler called for signal "+sig);
try {

// Output information for each thread
Thread[] threadArray = new Thread[Thread.activeCount()];
int numThreads = Thread.enumerate(threadArray);
System.out.println("Current threads:");
for (int i=0; i < numThreads; i++) {

System.out.println(" "+threadArray[i] + ", " + threadArray[i].getThreadGroup().getName());
if(threadArray[i].getThreadGroup().getName().equalsIgnoreCase("AAA")){

threadArray[i].interrupt();

}

}

for (int i=0; i < numThreads; i++) {

if((threadArray[i] != null) && (threadArray[i].getThreadGroup() != null) &&
(threadArray[i].getThreadGroup().getName().equalsIgnoreCase("AAA"))){

threadArray[i].join();

}

}

// Chain back to previous handler, if one exists
if ( oldHandler != SIG_DFL && oldHandler != SIG_IGN ) {

oldHandler.handle(sig);

}

} catch (Exception e) {

System.out.println("Signal handler failed, reason "+e);
e.printStackTrace();

}

}

}
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Heinz[2] mentioned the signal lists in different OSs:
Windows: ABRT, FPE, ILL, INT, SEGV, TERM

Solaris: ABRT, ALRM, BUS, CHLD, CONT, EMT, FPE, HUP, ILL, INT, IO, KILL, PIPE, POLL, PROF, PWR, QUIT, SEGV, STOP, SYS, TERM, TRAP, TSTP TTIN, TTOU, URG, USR1, USR2, VTALRM, WINCH, XCPU, XFSZ

References:

Chris White, Revelations on Java signal handling and termination, http://www.ibm.com/developerworks/ibm/library/i-signalhandling/
Dr. Heinz M. Kabutz, Switching off OS signals at runtime,
http://www.roseindia.net/javatutorials/
switching_off_os_signals_at_runtime.shtml

Java: construct a class with parameters in reflection

Here is a simple example for constructing a object with two parameters in Java Reflection:

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import java.lang.reflect.*;

public class LoadParamObject {

public LoadParamObject() {}

public LoadParamObject(int a, String b) {

System.out.println("a = " + a + " b = " + b);

}

public static void main(String args[]) {

try {

Class cls = Class.forName("LoadParamObject");
Class partypes[] = new Class[2];
partypes[0] = Integer.TYPE;
partypes[1] = String.class;
Constructor ct = cls.getConstructor(partypes);
Object arglist[] = new Object[2];
arglist[0] = new Integer(37);
arglist[1] = new String("BBB");
Object retobj = ct.newInstance(arglist);

} catch (Throwable e) {

System.err.println(e);

}

}

}
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The detail explanation please read below:
http://java.sun.com/developer/technicalArticles/ALT/Reflection/