1. String - filename
2. File - java.io.File object
3. BuffereredReader
4. InputStream

2. Exception in thread "Animation Thread" java.lang.NullPointerException
3. at processing.core.PApplet.handleDraw(PApplet.java:2297)
4. at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:243)
5. at processing.core.PApplet.run(PApplet.java:2140)
6. at java.lang.Thread.run(Thread.java:680)

2.   background(#ddddcc);
3.   size(456, 312);
4.   pg=createGraphics(sketchWidth, sketchHeight, JAVA2D);
5.   //pg2=createGraphics(sketchWidth, sketchHeight, JAVA2D);
6.   createGUI();
7.   customGUI();
8.   sketchPad1.setGraphic(pg);
9.   logscale.setEnabled(false);

2. import g4p_controls.*;
3. 
   
4. void setup(){
5.   size(480, 320);
6.   createGUI();
7.   
8. }
9. 
   
10. void draw(){
11.   
12. }

2. /* =========================================================
3.  * ====                   WARNING                        ===
4.  * =========================================================
5.  * The code in this tab has been generated from the GUI form
6.  * designer and care should be taken when editing this file.
7.  * Only add/edit code inside the event handlers i.e. only
8.  * use lines between the matching comment tags. e.g.
9. 
   
10.  void myBtnEvents(GButton button) { //_CODE_:button1:12356:
11.      // It is safe to enter your event code here  
12.  } //_CODE_:button1:12356:
13.  
14.  * Do not rename this tab!
15.  * =========================================================
16.  */
17. 
    
18. public void textfield1_change1(GTextField source, GEvent event) { //_CODE_:textfield1:971680:
19.   println("textfield1 - GTextField event occured " + System.currentTimeMillis()%10000000 );
20. } //_CODE_:textfield1:971680:
21. 
    
22. public void button1_click1(GButton source, GEvent event) { //_CODE_:button1:652347:
23.   println("button1 - GButton event occured " + System.currentTimeMillis()%10000000 );
24. } //_CODE_:button1:652347:
25. 
    
26. public void button2_click1(GButton source, GEvent event) { //_CODE_:button2:218684:
27.   println("button2 - GButton event occured " + System.currentTimeMillis()%10000000 );
28. } //_CODE_:button2:218684:
29. 
    
30. synchronized public void win_draw1(GWinApplet appc, GWinData data) { //_CODE_:window1:987016:
31.   appc.background(230);
32. } //_CODE_:window1:987016:
33. 
    
34. public void button3_click1(GButton source, GEvent event) { //_CODE_:button3:399616:
35.   println("button3 - GButton event occured " + System.currentTimeMillis()%10000000 );
36. } //_CODE_:button3:399616:
37. 
    
38. public void button4_click1(GButton source, GEvent event) { //_CODE_:button4:425051:
39.   println("button4 - GButton event occured " + System.currentTimeMillis()%10000000 );
40. } //_CODE_:button4:425051:
41. 
    
42. public void dropList1_click1(GDropList source, GEvent event) { //_CODE_:dropList1:784715:
43.   println("dropList1 - GDropList event occured " + System.currentTimeMillis()%10000000 );
44. } //_CODE_:dropList1:784715:
45. 
    
46. 
    
47. 
    
48. // Create all the GUI controls. 
49. // autogenerated do not edit
50. public void createGUI(){
51.   G4P.messagesEnabled(false);
52.   G4P.setGlobalColorScheme(GCScheme.BLUE_SCHEME);
53.   G4P.setCursor(ARROW);
54.   if(frame != null)
55.     frame.setTitle("Sketch Window");
56.   textfield1 = new GTextField(this, 160, 145, 160, 30, G4P.SCROLLBARS_NONE);
57.   textfield1.setOpaque(true);
58.   textfield1.addEventHandler(this, "textfield1_change1");
59.   label1 = new GLabel(this, 260, 70, 80, 20);
60.   label1.setText("My label");
61.   label1.setOpaque(false);
62.   button1 = new GButton(this, 85, 73, 80, 30);
63.   button1.setText("Face text");
64.   button1.addEventHandler(this, "button1_click1");
65.   button2 = new GButton(this, 68, 197, 80, 36);
66.   button2.setText("Face text");
67.   button2.addEventHandler(this, "button2_click1");
68.   sketchPad1 = new GSketchPad(this, 333, 120, 142, 176);
69.   sketchPad1.setOpaque(false);
70.   window1 = new GWindow(this, "Window title", 0, 0, 240, 120, false, JAVA2D);
71.   window1.addDrawHandler(this, "win_draw1");
72.   button3 = new GButton(window1.papplet, 17, 12, 80, 30);
73.   button3.setText("Face text");
74.   button3.addEventHandler(this, "button3_click1");
75.   button4 = new GButton(window1.papplet, 20, 59, 80, 30);
76.   button4.setText("Face text");
77.   button4.addEventHandler(this, "button4_click1");
78.   dropList1 = new GDropList(window1.papplet, 131, 34, 90, 66, 3);
79.   dropList1.setItems(loadStrings("list_784715"), 0);
80.   dropList1.addEventHandler(this, "dropList1_click1");
81. }
82. 
    
83. // Variable declarations 
84. // autogenerated do not edit
85. GTextField textfield1; 
86. GLabel label1; 
87. GButton button1; 
88. GButton button2; 
89. GSketchPad sketchPad1; 
90. GWindow window1;
91. GButton button3; 
92. GButton button4; 
93. GDropList dropList1; 

2. Exception in thread "Animation Thread" java.lang.NullPointerException
3. at processing.core.PApplet.handleDraw(PApplet.java:2297)
4. at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:243)
5. at processing.core.PApplet.run(PApplet.java:2140)
6. at java.lang.Thread.run(Thread.java:680)

So I only click once on the first and I click on the second one until I don't see the Exception anymore.

1. GWindow gwin;

1. gwin = null;
2. boolean success = true;
3. do {
4.   try {
5.     gwin = new GWindow(this, blah blah blah);
6.   }
7.   catch(Exception e) {
8.     if (gwin != null)
9.       gwin.close();
10.     success = false;
11.   }
12. }
13. while (!success);
14. // Window created and gwin != null
    

Now the only thing I would want to do, it to be able to call a method of mine when the window is closing. Because I have an ArrayList of my currently opened windows that I would want to update only when I open or close a new GWindow.