我的第一个J2ME程序(计算器)

package testmidlet; import javax.microedition.lcdui.*; public class TestScreen extends Form implements CommandListener { private TextField intA = new TextField("请输入数字a", "0", 10, TextField.DECIMAL); private TextField intB = new TextField("请输入数字b", "0", 10, TextField.DECIMAL); private TextField result = new TextField("运算结果：", "0", 10, TextField.ANY); private ChoiceGroup opt = new ChoiceGroup("运算：", ChoiceGroup.EXCLUSIVE); String[] op = {"+", "-", "*", "/"}; public TestScreen() { super("计算器"); try { jbInit(); } catch (Exception e) { e.printStackTrace(); } } private void jbInit() throws Exception { opt.append(op[0], null); opt.append(op[1], null); opt.append(op[2], null); opt.append(op[3], null); append(intA); append(intB); append(opt); append(result); setCommandListener(this); addCommand(new Command("退出", Command.EXIT, 1)); addCommand(new Command("计算", Command.OK, 2)); } private void performAddAction() { int a, b, r = 0; a = Integer.parseInt(intA.getString()); b = Integer.parseInt(intB.getString()); if (op[opt.getSelectedIndex()].equals("+")) { r = a + b; } if (op[opt.getSelectedIndex()].equals("-")) { r = a - b; } if (op[opt.getSelectedIndex()].equals("*")) { r = a * b; } if (op[opt.getSelectedIndex()].equals("/")) { if (b == 0) { result.setString("除数不能为0！"); return; } r = a / b; } result.setString(Integer.toString(r)); } public void commandAction(Command commd, Displayable displayable) { if (commd.getCommandType() == Command.EXIT) { TestMidlet.quitApp(); } if (commd.getCommandType() == Command.OK) { performAddAction(); } } }