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POProgram not recognizing ArrayList Index
 

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  1. POProgram not recognizing ArrayList Index
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    <p>Below I've posted a snippet of my code that I am having some trouble with. Every time I run this program I get an error saying that </p> <blockquote> <p>Exception in thread "AWT-EventQueue-1" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0</p> </blockquote> <p>Or in other words that the ArrayList isn't being created before I try and change values in it later on. What's really weird, however, is that when I replace realmHeight and realmWidth in the first for loop condition then I have no issues and the program works as intended. Could anyone shed some light as to why this is?</p> <p>Btw, realmHeight and realmWidth take a String as a parameter for a filename, read from that file and spit out the correct max width and max height (in the printlns).</p> <pre><code>public class GuiMap extends Gui { private ArrayList&lt;ArrayList&lt;GuiTile&gt;&gt; map = new ArrayList&lt;ArrayList&lt;GuiTile&gt;&gt;(); private TileSet tileSet = new TileSet(); private int tileSize; private String realm; public GuiMap(String name, String Realm) { super(name, 0, 0, 950, 600); realm = Realm; int realmHeight = getHeight() * 3; int realmWidth = getWidth()*3; try { realmHeight = countHeight(realm); realmWidth = countWidth(realm); } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } System.out.println("realmHeight: " + realmHeight + " realmWidth: " + realmWidth); tileSize = tileSet.get("grasslands")[0].getWidth(); //make the map arrayList fill the entire screen int nameNum = 0; for (int i = 0; i &lt; realmHeight; i++) { ArrayList&lt;GuiTile&gt; temporary = new ArrayList&lt;GuiTile&gt;(); for (int j = 0; j &lt; realmWidth; j++) { temporary.add(new GuiTile("Tile" + nameNum, j*tileSize, i*tileSize, tileSize, tileSet.get("grasslands"))); nameNum++; } map.add(temporary); } BufferedReader br = null; try { br = new BufferedReader(new FileReader(realm)); } catch (FileNotFoundException e) { e.printStackTrace(); System.out.println("Couldn't find file to generate map from"); } String currentLine = null; try { int i = 0; while ((currentLine = br.readLine()) != null) { char[] line = currentLine.toCharArray(); ArrayList&lt;GuiTile&gt; temp = new ArrayList&lt;GuiTile&gt;(); for (int j = 0; j &lt; currentLine.length(); j++) { switch (line[j]) { case '0': map.get(i).get(j).tileValue = 0; break; case '1': map.get(i).get(j).tileValue = 1; break; case '2': map.get(i).get(j).tileValue = 2; break; case '3': map.get(i).get(j).tileValue = 3; break; default: map.get(i).get(j).tileValue = 0; break; } } map.add(temp); i++; } } catch (IOException e) { System.out.println("Couldn't read from file. Please check map file"); } } } </code></pre> <p>EDIT: Stacktrace:</p> <pre><code>Exception in thread "AWT-EventQueue-1" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.rangeCheck(ArrayList.java:604) at java.util.ArrayList.get(ArrayList.java:382) at gg.mc.OneQuest.gui.GuiMap.&lt;init&gt;(GuiMap.java:81) at gg.mc.OneQuest.Game.&lt;init&gt;(Game.java:27) at gg.mc.OneQuest.gui.GuiLogin.login(GuiLogin.java:76) at gg.mc.OneQuest.gui.GuiLogin.access$0(GuiLogin.java:73) at gg.mc.OneQuest.gui.GuiLogin$1.run(GuiLogin.java:36) at gg.mc.OneQuest.gui.GuiButton.onClicked(GuiButton.java:30) at gg.mc.OneQuest.gui.Gui$1.run(Gui.java:31) at gg.mc.OneQuest.engine.Mouse$1.mouseClicked(Mouse.java:26) at java.awt.Component.processMouseEvent(Component.java:6507) at java.awt.Component.processEvent(Component.java:6269) at java.awt.Container.processEvent(Container.java:2229) at java.awt.Component.dispatchEventImpl(Component.java:4860) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4686) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707) at java.awt.EventQueue.access$000(EventQueue.java:101) at java.awt.EventQueue$3.run(EventQueue.java:666) at java.awt.EventQueue$3.run(EventQueue.java:664) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:680) at java.awt.EventQueue$4.run(EventQueue.java:678) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:677) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105) at java.awt.EventDispatchThread.run(EventDispatchThread.java:90) </code></pre>
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    1. COHave you debugged into it? What are `getHeight()` and `getWidth()` returning?
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    2. COoh, getHeight and getWidth return 650 and 900 respectively. They are the functions that return the bounding box dimensions of the window. Furthermore, the realmHeight and realmWidth functions print 45 and 36 respectively (in the println).
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    3. COWhy do you always add an empty list in your second loop? (`map.add(temp)`). That looks pointless to me.
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