import java.lang.*; import java.awt.*; import java.applet.*; /* * Purpose: The main program of the applet */ public class BinarySearch extends Applet { public void init() { setLayout(new BorderLayout()); BTextPanel WritingArea = new BTextPanel(); BSearchPanel DrawingArea = new BSearchPanel(); BMainPanel MainArea = new BMainPanel(DrawingArea, WritingArea); add("Center", MainArea); add("North", new BControlPanel(MainArea, this)); } } /* * Purpose: The container panel for the whole applet */ class BMainPanel extends Panel { public BSearchPanel panel1; public BTextPanel panel2; public BMainPanel(BSearchPanel p, BTextPanel t) { panel1 = p; panel2 = t; setLayout(new GridLayout(2, 1)); /* 2 rows, 1 column */ add(p); add(t); } } /* * Purpose: Drawing the text description */ class BTextPanel extends Panel { private int TOPMARGIN=50; private int LEFTMARGIN=30; public boolean AnimationNext[] = new boolean[15]; public int NextStep=0; private Font f; private String Description[][] = new String[15][5]; public BTextPanel() { setBackground(new Color(255, 248, 220)); /* set background as cornsilk */ f = new Font("Helvetica", Font.PLAIN, 16); Description[0][0] = "At first the entire array is unknown but sorted."; Description[0][1] = "We try to search the value 10 as an example."; Description[0][2] = ""; Description[0][3] = ""; Description[0][4] = ""; AnimationNext[0] = true; Description[1][0] = "Divide the array into two parts and examine "; Description[1][1] = "the middle value in the array. The index of the"; Description[1][2] = "middle value is calculated by the formula:"; Description[1][3] = "(start_index + end_index )/2 (ie. the value"; Description[1][4] = "with index 4 in this case)."; AnimationNext[1] = false; Description[2][0] = "This value (7) is not the one we searched, "; Description[2][1] = "so we need to continue the search."; Description[2][2] = ""; Description[2][3] = ""; Description[2][4] = ""; AnimationNext[2] = false; Description[3][0] = "Since the array is sorted, the portion before the"; Description[3][1] = "value 7 will be smaller than 7. Thus, all values"; Description[3][2] = "in this portion are also smaller than the search "; Description[3][3] = "value 10"; Description[3][4] = ""; AnimationNext[3] = true; Description[4][0] = "Therefore, we can deduce that the search value"; Description[4][1] = "will not be located at the portion of the array"; Description[4][2] = "before the value 7."; Description[4][3] = ""; Description[4][4] = ""; AnimationNext[4] = true; Description[5][0] = "Thus, we continue to search the remaining part"; Description[5][1] = "of the array. We do the same thing: divide this"; Description[5][2] = "part into two and examine the middle value --"; Description[5][3] = "the value with index 8."; Description[5][4] = ""; AnimationNext[5] = true; Description[6][0] = "By similar argument, we can deduce that the"; Description[6][1] = "search value is equal to none of the values"; Description[6][2] = "in the array with index 7-9."; Description[6][3] = ""; Description[6][4] = ""; AnimationNext[6] = true; Description[7][0] = "Repeat the process, this time we examine the "; Description[7][1] = "value with index ((6+7) div 2) (ie. 5). After we"; Description[7][2] = "find that it is not the answer, we finally locate"; Description[7][3] = "the value need to be searched."; Description[7][4] = ""; AnimationNext[7] = true; Description[8][0] = "Notice that the number of values examined is"; Description[8][1] = "only four. If linear search is used instead, we"; Description[8][2] = "need to examine seven values."; Description[8][3] = ""; Description[8][4] = ""; AnimationNext[8] = true; } public void paint(Graphics g) { g.drawRect(0, 0, size().width-1, size().height-1); g.setFont(f); for (int i=0; i<5; i++) { g.drawString(Description[NextStep][i], LEFTMARGIN, TOPMARGIN+18*i); } } public void Next() { NextStep++; repaint(); } public void reset() { NextStep=0; repaint(); } } /* * Purpose: the control panel */ class BControlPanel extends Panel { BMainPanel MainArea; Button b2, b3, bsound; Checkbox cb_sound; Applet applet; boolean voice = false; AudioClip ac=null; String sound[] = new String[9]; public BControlPanel(BMainPanel m, Applet app) { MainArea = m; applet = app; sound[0] = "sound/binary1.au"; sound[1] = "sound/binary2.au"; sound[2] = "sound/binary3.au"; sound[3] = "sound/binary4.au"; sound[4] = "sound/binary5.au"; sound[5] = "sound/binary6.au"; sound[6] = "sound/binary7.au"; sound[7] = "sound/binary8.au"; sound[8] = "sound/binary9.au"; setLayout(new FlowLayout(FlowLayout.LEFT)); setBackground(Color.lightGray); b2 = new Button(" Next "); reset(); add(b2); cb_sound = new Checkbox("Voice Description"); cb_sound.setState(false); add(cb_sound); } public boolean action(Event e, Object arg) { if (e.target instanceof Button) { String str = ((Button)(e.target)).getLabel(); if (str.equals(" Next ")) { b2.disable(); cb_sound.disable(); if (MainArea.panel2.AnimationNext[MainArea.panel2.NextStep]) MainArea.panel1.Next(); MainArea.panel2.Next(); if (voice) { /* applet.play(applet.getCodeBase(), sound[MainArea.panel2.NextStep]); */ if (ac != null) ac.stop(); ac = applet.getAudioClip(applet.getCodeBase(), sound[MainArea.panel2.NextStep]); ac.play(); } cb_sound.enable(); if (MainArea.panel2.NextStep != 8) b2.enable(); else { b2.setLabel("Restart"); b2.enable(); } } else if (str.equals("Restart")) { MainArea.panel1.reset(); MainArea.panel2.reset(); b2.setLabel(" Next "); reset(); } else if (str.equals("Voice Description")) { System.out.println(applet.getCodeBase()); applet.play(applet.getCodeBase(), sound[MainArea.panel2.NextStep]); } else if (str.equals("Disable Voice")) { voice = false; bsound.setLabel("Enable Voice"); } else if (str.equals("Enable Voice")) { voice = true; bsound.setLabel("Disable Voice"); applet.play(applet.getCodeBase(), sound[MainArea.panel2.NextStep]); } } else if (e.target instanceof Checkbox) { Checkbox cb = (Checkbox)e.target; String str = cb.getLabel(); if (str.equals("Voice Description")) { if (cb.getState()) { voice = true; /* applet.play(applet.getCodeBase(), sound[MainArea.panel2.NextStep]); */ if (ac != null) ac.stop(); ac = applet.getAudioClip(applet.getCodeBase(), sound[MainArea.panel2.NextStep]); ac.play(); } else { voice = false; ac.stop(); } } } return true; } public void reset() { b2.enable(); } }