JAVA计算器【源码】

1. import javax.microedition.midlet.*;
3. import javax.microedition.lcdui.*;

3. /**
4. * 该类是应用程序的主类，控制应用程序的生命周期。
5. */
6. public class CalcMIDlet extends MIDlet implements CommandListener {
7. //
8. private CalcForm calcForm;
9. private Command cmdExit = new Command("退出", Command.EXIT, 1);
11. public void startApp() {
12. Display display = Display.getDisplay(this);
13. calcForm = new CalcForm();
14. calcForm.addCommand(cmdExit);
15. calcForm.setCommandListener(this);
16. display.setCurrent(calcForm);
17. }
19. public void pauseApp() {
20. //
21. }
23. public void destroyApp(boolean unconditional) {
24. //
25. }
27. public void commandAction(Command cmd, Displayable d) {
28. if(cmd == cmdExit) {
29. notifyDestroyed();
30. }
31. }
32. }

Java代码

1. import javax.microedition.lcdui.*;
3. /**
4. * 该类描述了计算器。
5. * 实现了计算器的界面，及加、减、乘、除等计算功能。
6. */
7. public class CalcForm extends Form implements CalcKeyboardListener { //
8. private CalcScreen showArea; //计算器的显示区
9. private CalcKeyboard ckeyboard; //计算器键盘
11. private boolean hasNewOperand = false; //有新的操作数
12. private boolean numInputing = false;
13. private double acc = 0.0; //累加器
14. private String operator = ""; //运算符
15. private double operand = 0.0; //操作数
17. public CalcForm() {
18. super("计算器");
19. showArea = new CalcScreen(); //创建计算器的显示区对象
20. ckeyboard = new CalcKeyboard(4, 5); //创建计算器的键盘
21. ckeyboard.setCalcKeyboardListener(this); //
23. //布局
24. showArea.setLayout(Item.LAYOUT_2|Item.LAYOUT_CENTER|Item.LAYOUT_NEWLINE_AFTER);
25. append(showArea);
26. append(new Spacer(this.getWidth(), 5));
27. ckeyboard.setLayout(Item.LAYOUT_2|Item.LAYOUT_CENTER);
28. append(ckeyboard);
30. reset();
31. }
33. //按钮单击事件处理方法
34. //如果设备支持触摸屏功能，当用户使用笔在按钮上单击后，
35. //注册在键盘上的监视器将调用下面的方法，对单击事件进行处理。
36. public void actionPerformmed(CalcKeyboard btn, String symbol) {
37. if(symbol == CalcKeyboard.NUM_ZERO || symbol == CalcKeyboard.NUM_ONE || symbol == CalcKeyboard.NUM_TWO ||
38. symbol == CalcKeyboard.NUM_THREE ||symbol == CalcKeyboard.NUM_FOUR ||symbol == CalcKeyboard.NUM_FIVE ||
39. symbol == CalcKeyboard.NUM_SIX ||symbol == CalcKeyboard.NUM_SEVEN ||symbol == CalcKeyboard.NUM_EIGHT ||
40. symbol == CalcKeyboard.NUM_NINE ) {
41. //
42. inputNum(symbol);
43. }
44. else if(symbol == CalcKeyboard.SYMBOL_DOT
45. && showArea.getText().indexOf(CalcKeyboard.SYMBOL_DOT) == -1) {
46. //
47. inputNum(symbol);
48. }
49. else if(symbol == CalcKeyboard.BACKSPACE) {
50. String text = showArea.getText();
51. if(text.length() > 0) {
52. text = text.substring(0, text.length()-1);
53. showArea.setText(text);
54. }
55. }
56. else if(symbol == CalcKeyboard.CE) {
57. showArea.setText("0.");
58. }
59. else if(symbol == CalcKeyboard.C) {
60. //计算器归零
61. reset();
62. }
63. else if(symbol == CalcKeyboard.ADD || symbol == CalcKeyboard.MINUS ||
64. symbol == CalcKeyboard.MULT || symbol == CalcKeyboard.DIVIDE ||
65. symbol == CalcKeyboard.EQUALS) {
66. //
67. numInputing = false;
68. String s = showArea.getText();
69. double d = Double.parseDouble(s);
70. jisuan(d, symbol);
71. showArea.setText(String.valueOf(acc));
72. }
73. else if(symbol == CalcKeyboard.SYMBOL_MINUS) {
74. String str = showArea.getText();
75. if(str.charAt(0) == '-') {
76. showArea.setText(str.substring(1, str.length()));
77. }
78. else {
79. showArea.setText("-" + str);
80. }
81. }
82. }
84. private void jisuan(double exp, String oper) {
85. if(operator.equals("")) {
86. acc = exp;
87. operand = exp;
88. }
89. else {
90. if(hasNewOperand) { //新的操作数
91. operand = exp;
92. if(operator.equals(CalcKeyboard.ADD)) {
93. acc += operand;
94. }
95. else if(operator.equals(CalcKeyboard.MINUS)) {
96. acc -= operand;
97. }
98. else if(operator.equals(CalcKeyboard.MULT)) {
99. acc *= operand;
100. }
101. else if(operator.equals(CalcKeyboard.DIVIDE)) {
102. acc /= operand;
103. }
105. }
106. else {
107. if(oper.equals(CalcKeyboard.EQUALS)) {
108. if(operator.equals(CalcKeyboard.ADD)) {
109. acc += operand;
110. }
111. else if(operator.equals(CalcKeyboard.MINUS)) {
112. acc -= operand;
113. }
114. else if(operator.equals(CalcKeyboard.MULT)) {
115. acc *= operand;
116. }
117. else if(operator.equals(CalcKeyboard.DIVIDE)) {
118. acc /= operand;
119. }
120. if(!oper.equals(CalcKeyboard.EQUALS)) {
121. operator = oper;
122. }
123. }
124. }
125. }
126. if(!oper.equals(CalcKeyboard.EQUALS)) {
127. operator = oper;
128. }
129. hasNewOperand = false;
130. }
132. private void reset() {
133. hasNewOperand = false;
134. numInputing = false;
135. acc = 0.0;
136. operator = "";
137. showArea.setText("0.");
138. }
140. private void inputNum(String str) {
141. if(numInputing) {
142. showArea.setText(showArea.getText() + str);
143. }
144. else {
145. showArea.setText(str);
146. numInputing = true;
147. }
148. hasNewOperand = true;
149. }
150. }

Java代码

1. import javax.microedition.lcdui.*;
3. /**
4. * 该类描述了计算器键盘。提供了直观的图形用户界面，该类支持触摸屏功能。
5. */
6. public class CalcKeyboard extends CustomItem {
7. public static final String BACKSPACE = "<-";
8. public static final String CE = "CE";
9. public static final String C = "C";
10. public static final String SYMBOL_MINUS = "+/-";
11. public static final String NUM_ZERO = "0";
12. public static final String NUM_ONE = "1";
13. public static final String NUM_TWO = "2";
14. public static final String NUM_THREE = "3";
15. public static final String NUM_FOUR = "4";
16. public static final String NUM_FIVE = "5";
17. public static final String NUM_SIX = "6";
18. public static final String NUM_SEVEN = "7";
19. public static final String NUM_EIGHT = "8";
20. public static final String NUM_NINE = "9";
21. public static final String SYMBOL_DOT = ".";
22. public static final String ADD = "+";
23. public static final String MINUS = "-";
24. public static final String MULT = "*";
25. public static final String DIVIDE = "/";
26. public static final String EQUALS = "=";
28. private static final int PRESSED = 0;
29. private static final int RELEASED = 1;
31. private CalcKeyboardListener ckListener; //指针动作监视器
32. private Font textFont;
33. private int col; //列
34. private int row; //行
35. private int btnWidth; //按键宽
36. private int btnHeight; //按键高
37. private int hSpace = 4; //按键水平间距
38. private int vSpace = 4; //按键垂直间距
40. private int keyState = RELEASED;
42. private String[] keyLabel = {
43. BACKSPACE, CE, C, SYMBOL_MINUS,
44. NUM_SEVEN, NUM_EIGHT, NUM_NINE, DIVIDE,
45. NUM_FOUR, NUM_FIVE, NUM_SIX, MULT,
46. NUM_ONE, NUM_TWO, NUM_THREE, MINUS,
47. NUM_ZERO, SYMBOL_DOT, EQUALS, ADD
48. };
50. public CalcKeyboard(int col, int row) {
51. super(null);
52. textFont = Font.getFont(Font.FACE_SYSTEM, Font.STYLE_BOLD, Font.SIZE_LARGE);
53. this.col = col;
54. this.row = row;
55. btnHeight = textFont.getHeight() + 4;
56. btnWidth = btnHeight + 10;
57. }
59. protected int getMinContentHeight() {
60. return row * (btnHeight + vSpace) - vSpace;
61. }
63. protected int getMinContentWidth() {
64. return col * (btnWidth + hSpace) - hSpace;
65. }
67. protected int getPrefContentHeight(int width) {
68. return getMinContentHeight();
69. }
71. protected int getPrefContentWidth(int height) {
72. return getMinContentWidth();
73. }
75. protected void paint(Graphics g, int w, int h) {
76. for(int i=0; i<keyLabel.length; i++) {
77. drawButton(g, keyLabel[i], i%col * (btnWidth+hSpace), i/col*(btnHeight+vSpace), btnWidth, btnHeight);
78. }
79. }
81. private void drawButton(Graphics g, String str, int x, int y, int w, int h) {
82. g.setColor(160, 160, 255);
83. g.drawRect(x, y, w-1, h-1);
84. if(keyState == RELEASED) {
85. g.setColor(240, 240, 255);
86. }
87. else if(keyState == PRESSED) {
88. g.setColor(210, 210, 255);
89. }
90. g.fillRect(x+2, y+2, w-4, h-4);
92. g.setColor(0, 0, 0);
93. g.setFont(textFont);
94. g.drawString(str, x+w/2, y+h, Graphics.BOTTOM|Graphics.HCENTER);
95. }
97. private int getIndex(int x, int y) {
98. int j = x / (btnWidth+hSpace);
99. int i = y / (btnHeight+vSpace);
101. return (col*i)+j;
102. }
104. //指针事件处理方法
105. //如果当前设备支持触摸屏功能,当用户使用笔在屏幕上按下时,
106. //系统将调用该方法。
107. protected void pointerPressed(int x, int y) {
108. keyState = PRESSED;
109. int ax = x - x % (btnWidth+hSpace);
110. int ay = y - y % (btnHeight+vSpace);
111. repaint(ax, ay, btnWidth, btnHeight);
112. }
114. //指针事件处理方法
115. //如果当前设备支持触摸屏功能,当用户使用笔在屏幕上按下,然后释放时,
116. //系统将调用该方法。
117. protected void pointerReleased(int x, int y) {
118. keyState = RELEASED;
119. int ax = x - x % (btnWidth+hSpace);
120. int ay = y - y % (btnHeight+vSpace);
121. repaint(ax, ay, btnWidth, btnHeight);
122. if(ckListener != null) {
123. int index = getIndex(x, y);
124. ckListener.actionPerformmed(this, keyLabel[index]);
125. }
126. }
128. //为当前计算器键盘设置监视器
129. public void setCalcKeyboardListener(CalcKeyboardListener ckListener) {
130. this.ckListener = ckListener;
131. }
132. }
135. /**
136. * 该接口描述了计算器键盘的监视器，定义了计算器键盘按钮单击动作
137. * 的处理方法。
138. */
139. public interface CalcKeyboardListener {
140. //指针单击动作的处理方法。
141. //如果设备支持触摸屏功能，当用户使用笔单击屏幕上计算盘键盘上的按钮
142. //时，监视该键盘的监视器将回调该方法，处理单击动作。
143. //参数ck表示被监视的计算器键盘，symbol表示键盘上的按键。
144. public void actionPerformmed(CalcKeyboard ck, String symbol);
145. }

Java代码

1. import javax.microedition.lcdui.*;
3. /**
4. * 该类描述了计算器的显示区，用于显示输入的操作数及计算结果。
5. */
6. public class CalcScreen extends CustomItem {
7. private String text;
8. private Font showFont;
10. public CalcScreen() {
11. super(null);
12. showFont = Font.getFont(Font.FACE_SYSTEM, Font.STYLE_BOLD, Font.SIZE_LARGE);
13. text = "";
14. }
16. protected int getMinContentHeight() {
17. return showFont.getHeight() + 4;
18. }
20. protected int getMinContentWidth() {
21. return showFont.stringWidth("012345678901234.-") + 4;
22. }
24. protected int getPrefContentHeight(int width) {
25. return getMinContentHeight();
26. }
28. protected int getPrefContentWidth(int height) {
29. return 150;
30. }
32. protected void paint(Graphics g, int w, int h) {
33. g.setColor(160, 160, 255);
34. g.drawRect(0, 0, w-1, h-1);
35. g.setColor(210, 210, 255);
36. g.drawRect(2, 2, w-5, h-5);
38. g.setColor(0, 0, 0);
39. g.setFont(showFont);
40. g.drawString(text, w-10, h-3, Graphics.BOTTOM|Graphics.RIGHT);
41. }
43. public void setText(String text) {
44. this.text = text;
45. repaint();
46. }
48. public String getText() {
49. return text;
50. }
51. }