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POGetting the error " Cannot find symbol " on getdocumentBase()
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copied!<p>Despite I import the applet library, NetBeans cannot recognize and use getDocumentBase() in my code, I have my html file within my project and all other required files as well, here is a part of my code :</p> <pre><code>import java.awt.*; import java.applet.*; public class AirportCanvas extends Canvas { SingleLaneAirport controller; Image redPlane; Image bluePlane; Image airport; //AudioClip crashSound; int[] redX,redY,blueX,blueY; int maxCar = 2; final static int initredX = 5; final static int initredY = 55; final static int initblueX = 410; final static int initblueY = 130; final static int bridgeY = 90; boolean frozen = false; int cycleTime = 20; AirportCanvas(SingleLaneAirport controller) { super(); this.controller = controller; // crashSound=controller.getAudioClip(controller.getDocumentBase(),"crash.au"); MediaTracker mt; mt = new MediaTracker(this); redPlane = controller.getImage(controller.getDocumentBase(), "redplane.png"); mt.addImage(redPlane, 0); bluePlane = controller.getImage(controller.getDocumentBase(), "blueplane.png"); mt.addImage(bluePlane, 1); airport = controller.getImage(controller.getDocumentBase(), "airport.png"); mt.addImage(airport, 2); try { mt.waitForID(0); mt.waitForID(1); mt.waitForID(2); } catch (java.lang.InterruptedException e) { System.out.println("Couldn't load one of the images"); } setSize(airport.getWidth(null),airport.getHeight(null)); init(1); } public final void init(int ncars) { //set number of cars maxCar = ncars; frozen = false; redX = new int[maxCar]; redY = new int[maxCar]; blueX = new int[maxCar]; blueY = new int[maxCar]; for (int i = 0; i<maxCar ; i++) { redX[i] = initredX - i*85; redY[i] = initredY; blueX[i] =initblueX + i*85; blueY[i] =initblueY; } repaint(); } Image offscreen; Dimension offscreensize; Graphics offgraphics; public void backdrop() { Dimension d = getSize(); if ((offscreen == null) || (d.width != offscreensize.width) || (d.height != offscreensize.height)) { offscreen = createImage(d.width, d.height); offscreensize = d; offgraphics = offscreen.getGraphics(); offgraphics.setFont(new Font("Helvetica",Font.BOLD,36)); } offgraphics.setColor(Color.lightGray); offgraphics.drawImage(airport,0,0,this); } @Override public void paint(Graphics g) { update(g); } @Override public void update(Graphics g) { backdrop(); for (int i=0; i<maxCar; i++) { offgraphics.drawImage(redPlane,redX[i],redY[i],this); offgraphics.drawImage(bluePlane,blueX[i],blueY[i],this); } if (blueY[0]==redY[0] && Math.abs(redX[0]+80 - blueX[0])<5) { offgraphics.setColor(Color.red); offgraphics.drawString("Crunch!",200,100); frozen=true; // crashSound.play(); } g.drawImage(offscreen, 0, 0, null); } //returns true for the period from just before until just after car on bridge public boolean moveRed(int i) throws InterruptedException { int X = redX[i]; int Y = redY[i]; synchronized (this) { while (frozen ) wait(); if (i==0 || Math.abs(redX[i-1] - X) > 120) { X += 2; if (X >=500) { X = -80; Y = initredY; } if (X >=60 && X < 290 && Y<bridgeY) ++Y; if (X >=290 && Y>initredY) --Y; } redX[i]=X; redY[i]=Y; repaint(); } Thread.sleep(cycleTime); return (X>25 && X<400); } //returns true for the period from just before until just after car on bridge public boolean moveBlue(int i) throws InterruptedException { int X = blueX[i]; int Y = blueY[i]; synchronized (this) { while (frozen ) wait(); if (i==0 || Math.abs(blueX[i-1] - X) > 120) { X -= 2; if (X <=-80) { X = 500; Y = initblueY; } if (X <=370 && X > 130 && Y>bridgeY) --Y; if (X <=130 && Y<initblueY) ++Y; blueX[i]=X; } blueY[i]=Y; repaint(); } Thread.sleep(cycleTime); repaint(); return (X>25 && X<400); } public synchronized void freeze() { frozen = true; } public synchronized void thaw() { frozen = false; notifyAll(); } } </code></pre> <p>Single Lane Airport Class :</p> <pre><code>import java.awt.*; import java.awt.event.*; import java.applet.*; public class SingleLaneAirport { AirportCanvas display; Button restart; Button freeze; Button onecar; Button twocar; Button threecar; Checkbox fair; Checkbox safe; boolean fixed = false; int maxCar = 1; Thread red[]; Thread blue[]; @Override public void init() { setLayout(new BorderLayout()); display = new AirportCanvas(this); add("Center",display); restart = new Button("Restart"); restart.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { display.thaw(); } }); freeze = new Button("Freeze"); freeze.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { display.freeze(); } }); onecar = new Button("One Car"); onecar.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { stop(); maxCar = 1; start(); } }); twocar = new Button("Two Cars"); twocar.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { stop(); maxCar = 2; start(); } }); threecar = new Button("Three Cars"); threecar.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { stop(); maxCar = 3; start(); } }); safe = new Checkbox("Safe",null,true); safe.setBackground(Color.lightGray); safe.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent e) { stop(); start(); } }); fair = new Checkbox("Fair",null,false); fair.setBackground(Color.lightGray); fair.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent e) { stop(); start(); } }); Panel p1 = new Panel(); p1.setLayout(new FlowLayout()); p1.add(freeze); p1.add(restart); p1.add(onecar); p1.add(twocar); p1.add(threecar); p1.add(safe); p1.add(fair); add("South",p1); setBackground(Color.lightGray); } @Override public void start() { red = new Thread[maxCar]; blue = new Thread[maxCar]; display.init(maxCar); Airport b; if (fair.getState() && safe.getState()) b = new FairAirport(); else if ( safe.getState()) b = new SafeAirport(); else b = new Airport(); for (int i = 0; i<maxCar; i++) { red[i] = new Thread(new RedPlane(b,display,i)); blue[i] = new Thread(new BluePlane(b,display,i)); } for (int i = 0; i<maxCar; i++) { red[i].start(); blue[i].start(); } } @Override public void stop() { for (int i = 0; i<maxCar; i++) { red[i].interrupt(); blue[i].interrupt(); } } } </code></pre>

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