Admin: 1 версия

2010-06-01T06:58:34Z

1 версия

в 18:01, 31 мая 2010

2010-05-31T18:01:46Z

Новая страница

== Add a delay ==



<source lang="java">

public class Main {
public static void main(String[] args) {
for (int i = 0; i < 10; i++) {
System.out.println("i = " + i);
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
ie.printStackTrace();
}
}
}
}

</source>



== Another way to stop a thread ==



<source lang="java">

public class AlternateStop extends Object implements Runnable {
private volatile boolean stopRequested;
private Thread runThread;
public void run() {
runThread = Thread.currentThread();
stopRequested = false;
int count = 0;
while (!stopRequested) {
System.out.println("Running ... count=" + count);
count++;
try {
Thread.sleep(300);
} catch (InterruptedException x) {
// re-assert interrupt
Thread.currentThread().interrupt();
}
}
}
public void stopRequest() {
stopRequested = true;
if (runThread != null) {
runThread.interrupt();
}
}
public static void main(String[] args) {
AlternateStop as = new AlternateStop();
Thread t = new Thread(as);
t.start();
try {
Thread.sleep(2000);
} catch (InterruptedException x) {
}
as.stopRequest();
}
}

</source>



== Another way to suspend and resume ==



<source lang="java">

public class AlternateSuspendResume extends Object implements Runnable {
private volatile int firstVal;
private volatile int secondVal;
private volatile boolean suspended;
public boolean areValuesEqual() {
return (firstVal == secondVal);
}
public void run() {
try {
suspended = false;
firstVal = 0;
secondVal = 0;
workMethod();
} catch (InterruptedException x) {
System.out.println("interrupted in workMethod()");
}
}
private void workMethod() throws InterruptedException {
int val = 1;
while (true) {
// blocks if suspended is true
waitWhileSuspended();
stepOne(val);
stepTwo(val);
val++;
// blocks if suspended is true
waitWhileSuspended();
Thread.sleep(200); // pause before looping again
}
}
private void stepOne(int newVal) throws InterruptedException {
firstVal = newVal;
// simulate some other lengthy process
Thread.sleep(300);
}
private void stepTwo(int newVal) {
secondVal = newVal;
}
public void suspendRequest() {
suspended = true;
}
public void resumeRequest() {
suspended = false;
}
private void waitWhileSuspended() throws InterruptedException {
while (suspended) {
Thread.sleep(200);
}
}
public static void main(String[] args) {
AlternateSuspendResume asr = new AlternateSuspendResume();
Thread t = new Thread(asr);
t.start();
try {
Thread.sleep(1000);
} catch (InterruptedException x) {
}
for (int i = 0; i < 10; i++) {
asr.suspendRequest();
try {
Thread.sleep(350);
} catch (InterruptedException x) {
}
System.out.println("dsr.areValuesEqual()=" + asr.areValuesEqual());
asr.resumeRequest();
try {
Thread.sleep((long) (Math.random() * 2000.0));
} catch (InterruptedException x) {
}
}
System.exit(0);
}
}

</source>



== Daemon Thread ==



<source lang="java">

public class DaemonThread implements Runnable {
public void run() {
System.out.println("entering run()");
try {
System.out.println("in run(): currentThread() is"
+ Thread.currentThread());
while (true) {
try {
Thread.sleep(500);
} catch (InterruptedException x) {
}
System.out.println("in run(): woke up again");
}
} finally {
System.out.println("leaving run()");
}
}
public static void main(String[] args) {
System.out.println("entering main()");
Thread t = new Thread(new DaemonThread());
t.setDaemon(true);
t.start();
try {
Thread.sleep(3000);
} catch (InterruptedException x) {
}
System.out.println("leaving main()");
}
}

</source>



== Determining When a Thread Has Finished ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
Thread thread = new MyThread();
thread.start();
if (thread.isAlive()) {
System.out.println("Thread has not finished");
} else {
System.out.println("Finished");
}
long delayMillis = 5000; // 5 seconds
thread.join(delayMillis);
if (thread.isAlive()) {
System.out.println("thread has not finished");
} else {
System.out.println("Finished");
}
thread.join();
}
}
class MyThread extends Thread {
boolean stop = false;
public void run() {
while (true) {
if (stop) {
return;
}
}
}
}

</source>



== Interrupt a thread. ==



<source lang="java">

class MyThread implements Runnable {
public void run() {
System.out.println(Thread.currentThread().getName() + " starting.");
try {
Thread.sleep(30000);
for (int i = 1; i < 10; i++) {
if (Thread.interrupted()) {
System.out.println("interrupted.");
break;
}
System.out.print(".");
for (long x = 0; x < 1000; x++)
System.out.println("/");
}
} catch (Exception exc) {
System.out.println(Thread.currentThread().getName() + " interrupted.");
}
System.out.println(Thread.currentThread().getName() + " exiting.");
}
}
public class Main {
public static void main(String args[]) throws Exception {
Thread thrd = new Thread(new MyThread(), "MyThread #1");
Thread thrd2 = new Thread(new MyThread(), "MyThread #2");
thrd.start();
Thread.sleep(1000);
thrd.interrupt();
thrd2.start();
Thread.sleep(4000);
thrd2.interrupt();
}
}

</source>



== Is thread alive ==



<source lang="java">

public class TwoThreadAlive extends Thread {
public void run() {
for (int i = 0; i < 10; i++) {
printMsg();
}
}
public void printMsg() {
Thread t = Thread.currentThread();
String name = t.getName();
System.out.println("name=" + name);
}
public static void main(String[] args) {
TwoThreadAlive tt = new TwoThreadAlive();
tt.setName("Thread");
System.out.println("before start(), tt.isAlive()=" + tt.isAlive());
tt.start();
System.out.println("just after start(), tt.isAlive()=" + tt.isAlive());
for (int i = 0; i < 10; i++) {
tt.printMsg();
}
System.out.println("The end of main(), tt.isAlive()=" + tt.isAlive());
}
}

</source>



== Monitor a thread"s status. ==



<source lang="java">

class MyThread extends Thread{
boolean waiting= true;
boolean ready= false;
MyThread() {
}
public void run() {
String thrdName = Thread.currentThread().getName();
System.out.println(thrdName + " starting.");
while(waiting)
System.out.println("waiting:"+waiting);
System.out.println("waiting...");
startWait();
try {
Thread.sleep(1000);
} catch(Exception exc) {
System.out.println(thrdName + " interrupted.");
}
System.out.println(thrdName + " terminating.");
}
synchronized void startWait() {
try {
while(!ready) wait();
} catch(InterruptedException exc) {
System.out.println("wait() interrupted");
}
}
synchronized void notice() {
ready = true;
notify();
}
}
public class Main {
public static void main(String args[]) throws Exception{
MyThread thrd = new MyThread();
thrd.setName("MyThread #1");
showThreadStatus(thrd);
thrd.start();
Thread.sleep(50);
showThreadStatus(thrd);
thrd.waiting = false;
Thread.sleep(50);
showThreadStatus(thrd);
thrd.notice();
Thread.sleep(50);
showThreadStatus(thrd);
while(thrd.isAlive())
System.out.println("alive");
showThreadStatus(thrd);
}
static void showThreadStatus(Thread thrd) {
System.out.println(thrd.getName()+" Alive:"+thrd.isAlive()+" State:" + thrd.getState() );
}
}

</source>



== Pause the execution ==



<source lang="java">

class Wait {
public static void oneSec() {
try {
Thread.currentThread().sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void manySec(long s) {
try {
Thread.currentThread().sleep(s * 1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public class Main{
public static void main(String args[]) {
Wait.oneSec();
Wait.manySec(5);
}
}

</source>



== Pause the execution of a thread using sleep() ==



<source lang="java">

class Wait {
public static void oneSec() {
try {
Thread.currentThread().sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void manySec(long s) {
try {
Thread.currentThread().sleep(s * 1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public class Main {
public static void main(String args[]) {
System.out.println("Wait one second");
Wait.oneSec();
System.out.println("Done\nWait five seconds");
Wait.manySec(5);
System.out.println("Done");
}
}

</source>



== Pausing a Thread: set a variable that the thread checks occasionally, call Object.wait() ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
MyThread thread = new MyThread();
thread.start();
while (true) {
synchronized (thread) {
thread.pause = true;
}
synchronized (thread) {
thread.pause = false;
thread.notify();
}
}
}
}
class MyThread extends Thread {
boolean pause = false;
public void run() {
while (true) {
synchronized (this) {
while (pause) {
try {
wait();
} catch (Exception e) {
}
}
}
}
}
}

</source>



== Pausing the Current Thread: a thread can temporarily stop execution. ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
long numMillisecondsToSleep = 5000; // 5 seconds
Thread.sleep(numMillisecondsToSleep);
}
}

</source>



== set Uncaught Exception Handler ==



<source lang="java">

public class Uncaught implements Runnable {
public static void main(String[] args) {
Thread thread = new Thread(new Uncaught());
thread.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
public void uncaughtException(Thread t, Throwable e) {
e.printStackTrace();
}
});
thread.start();
}
public void run() {
throw new ArithmeticException();
}
}

</source>



== Stopping a Thread: set a variable that the thread checks occasionally ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
MyThread thread = new MyThread();
thread.start();
thread.stop = true;
}
}
class MyThread extends Thread {
boolean stop = false;
public void run() {
while (true) {
if (stop) {
return;
}
}
}
}

</source>



== Thread sleep ==



<source lang="java">

public class TwoThreadSleep extends Thread {
public void run() {
Thread t = Thread.currentThread();
String name = t.getName();
System.out.println("entered loop() - " + name);
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(200);
} catch (InterruptedException x) {
}
System.out.println("name=" + name);
}
System.out.println("leave loop() - " + name);
}
public static void main(String[] args) {
TwoThreadSleep tt = new TwoThreadSleep();
tt.setName("thread");
tt.start();
// pause for a bit
try {
Thread.sleep(700);
} catch (InterruptedException x) {
// ignore
}
}
}

</source>



== Thread sleep and interrupt ==



<source lang="java">

public class SleepInterrupt extends Object implements Runnable {
public void run() {
try {
System.out.println("in run() - sleep for 20 seconds");
Thread.sleep(20000);
System.out.println("in run() - woke up");
} catch (InterruptedException x) {
System.out.println("in run() - interrupted while sleeping");
return;
}
System.out.println("in run() - leaving normally");
}
public static void main(String[] args) {
SleepInterrupt si = new SleepInterrupt();
Thread t = new Thread(si);
t.start();
// Be sure that the new thread gets a chance to
// run for a while.
try {
Thread.sleep(2000);
} catch (InterruptedException x) {
}
System.out.println("in main() - interrupting other thread");
t.interrupt();
System.out.println("in main() - leaving");
}
}

</source>



== Visual suspend and resume ==



<source lang="java">

import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class SwingSuspendResume extends JPanel implements Runnable {
private static final String[] symbolList = { "|", "/", "-", "\\", "|", "/",
"-", "\\" };
private Thread runThread;
private JTextField symbolTF;
public SwingSuspendResume() {
symbolTF = new JTextField();
symbolTF.setEditable(false);
symbolTF.setFont(new Font("Monospaced", Font.BOLD, 26));
symbolTF.setHorizontalAlignment(JTextField.CENTER);
final JButton suspendB = new JButton("Suspend");
final JButton resumeB = new JButton("Resume");
suspendB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
suspendNow();
}
});
resumeB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
resumeNow();
}
});
JPanel innerStackP = new JPanel();
innerStackP.setLayout(new GridLayout(0, 1, 3, 3));
innerStackP.add(symbolTF);
innerStackP.add(suspendB);
innerStackP.add(resumeB);
this.setLayout(new FlowLayout(FlowLayout.CENTER));
this.add(innerStackP);
}
private void suspendNow() {
if (runThread != null) { // avoid NullPointerException
runThread.suspend();
}
}
private void resumeNow() {
if (runThread != null) { // avoid NullPointerException
runThread.resume();
}
}
public void run() {
try {
// Store this for the suspendNow() and
// resumeNow() methods to use.
runThread = Thread.currentThread();
int count = 0;
while (true) {
// each time through, show the next symbol
symbolTF.setText(symbolList[count % symbolList.length]);
Thread.sleep(200);
count++;
}
} catch (InterruptedException x) {
// ignore
} finally {
// make sure that the reference to it is also lost.
runThread = null;
}
}
public static void main(String[] args) {
SwingSuspendResume vsr = new SwingSuspendResume();
Thread t = new Thread(vsr);
t.start();
JFrame f = new JFrame();
f.setContentPane(vsr);
f.setSize(320, 200);
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
}

</source>

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Admin: 1 версия

в 18:01, 31 мая 2010