//: Counter5.java ////////////////////////////////////////////////// // Copyright (c) Bruce Eckel, 1998 // Source code file from the book "Thinking in Java" // All rights reserved EXCEPT as allowed by the // following statements: You can freely use this file // for your own work (personal or commercial), // including modifications and distribution in // executable form only. Permission is granted to use // this file in classroom situations, including its // use in presentation materials, as long as the book // "Thinking in Java" is cited as the source. // Except in classroom situations, you cannot copy // and distribute this code; instead, the sole // distribution point is http://www.BruceEckel.com // (and official mirror sites) where it is // freely available. You cannot remove this // copyright and notice. You cannot distribute // modified versions of the source code in this // package. You cannot use this file in printed // media without the express permission of the // author. Bruce Eckel makes no representation about // the suitability of this software for any purpose. // It is provided "as is" without express or implied // warranty of any kind, including any implied // warranty of merchantability, fitness for a // particular purpose or non-infringement. The entire // risk as to the quality and performance of the // software is with you. Bruce Eckel and the // publisher shall not be liable for any damages // suffered by you or any third party as a result of // using or distributing software. In no event will // Bruce Eckel or the publisher be liable for any // lost revenue, profit, or data, or for direct, // indirect, special, consequential, incidental, or // punitive damages, however caused and regardless of // the theory of liability, arising out of the use of // or inability to use software, even if Bruce Eckel // and the publisher have been advised of the // possibility of such damages. Should the software // prove defective, you assume the cost of all // necessary servicing, repair, or correction. If you // think you've found an error, please email all // modified files with clearly commented changes to: // Bruce@EckelObjects.com. (Please use the same // address for non-code errors found in the book.) ///////////////////////////////////////////////// // Adjusting the priorities of threads import java.awt.*; import java.awt.event.*; import java.applet.*; class Ticker2 extends Thread { private Button b = new Button("Toggle"), incPriority = new Button("up"), decPriority = new Button("down"); private TextField t = new TextField(10), pr = new TextField(3); // Display priority private int count = 0; private boolean runFlag = true; public Ticker2(Container c) { b.addActionListener(new ToggleL()); incPriority.addActionListener(new UpL()); decPriority.addActionListener(new DownL()); Panel p = new Panel(); p.add(t); p.add(pr); p.add(b); p.add(incPriority); p.add(decPriority); c.add(p); } class ToggleL implements ActionListener { public void actionPerformed(ActionEvent e) { runFlag = !runFlag; } } class UpL implements ActionListener { public void actionPerformed(ActionEvent e) { int newPriority = getPriority() + 1; if(newPriority > Thread.MAX_PRIORITY) newPriority = Thread.MAX_PRIORITY; setPriority(newPriority); } } class DownL implements ActionListener { public void actionPerformed(ActionEvent e) { int newPriority = getPriority() - 1; if(newPriority < Thread.MIN_PRIORITY) newPriority = Thread.MIN_PRIORITY; setPriority(newPriority); } } public void run() { while (true) { if(runFlag) { t.setText(Integer.toString(count++)); pr.setText( Integer.toString(getPriority())); } yield(); } } } public class Counter5 extends Applet { private Button start = new Button("Start"), upMax = new Button("Inc Max Priority"), downMax = new Button("Dec Max Priority"); private boolean started = false; private static final int SIZE = 10; private Ticker2[] s = new Ticker2[SIZE]; private TextField mp = new TextField(3); public void init() { for(int i = 0; i < s.length; i++) s[i] = new Ticker2(this); add(new Label("MAX_PRIORITY = " + Thread.MAX_PRIORITY)); add(new Label("MIN_PRIORITY = " + Thread.MIN_PRIORITY)); add(new Label("Group Max Priority = ")); add(mp); add(start); add(upMax); add(downMax); start.addActionListener(new StartL()); upMax.addActionListener(new UpMaxL()); downMax.addActionListener(new DownMaxL()); showMaxPriority(); // Recursively display parent thread groups: ThreadGroup parent = s[0].getThreadGroup().getParent(); while(parent != null) { add(new Label( "Parent threadgroup max priority = " + parent.getMaxPriority())); parent = parent.getParent(); } } public void showMaxPriority() { mp.setText(Integer.toString( s[0].getThreadGroup().getMaxPriority())); } class StartL implements ActionListener { public void actionPerformed(ActionEvent e) { if(!started) { started = true; for(int i = 0; i < s.length; i++) s[i].start(); } } } class UpMaxL implements ActionListener { public void actionPerformed(ActionEvent e) { int maxp = s[0].getThreadGroup().getMaxPriority(); if(++maxp > Thread.MAX_PRIORITY) maxp = Thread.MAX_PRIORITY; s[0].getThreadGroup().setMaxPriority(maxp); showMaxPriority(); } } class DownMaxL implements ActionListener { public void actionPerformed(ActionEvent e) { int maxp = s[0].getThreadGroup().getMaxPriority(); if(--maxp < Thread.MIN_PRIORITY) maxp = Thread.MIN_PRIORITY; s[0].getThreadGroup().setMaxPriority(maxp); showMaxPriority(); } } public static void main(String[] args) { Counter5 applet = new Counter5(); Frame aFrame = new Frame("Counter5"); aFrame.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); aFrame.add(applet, BorderLayout.CENTER); aFrame.setSize(300, 600); applet.init(); applet.start(); aFrame.setVisible(true); } } ///:~