J2ME从零开始（学习笔记4）

★ List组件

List是选择列表组件，为用户提供多种选择项，List有两种构造函数

List（String title , int listType）;

List( String title , int listType , String [ ] stringElements, Image[ ] imageElements);

第三个参数有三种，Choice.EXCLUSIVE, Choice.MULTIPLE, Choice.IMPLICIT，这里涉及到Choice这个接口，实际上List实现了Choice这个接口。

当然List和其他组件也有很多自己的方法，大家可以参见API

以下是些简单的List代码：

package J2ME001;import javax.microedition.lcdui.Choice;import javax.microedition.lcdui.Command;import javax.microedition.lcdui.CommandListener;import javax.microedition.lcdui.Display;import javax.microedition.lcdui.Displayable;import javax.microedition.lcdui.List;import javax.microedition.midlet.MIDlet;import javax.microedition.midlet.MIDletStateChangeException;public class ListMIDlet extends MIDlet implements CommandListener {private List excList;private List mulList;private List impList;private final Command cmdExcList = new Command("Exclusive", Command.ITEM, 1);private final Command cmdMulList = new Command("Multiple", Command.ITEM, 1);private final Command cmdImpList = new Command("Implicit", Command.ITEM, 1);private final Command cmdExit = new Command("Exit", Command.ITEM, 1);private Display display;public ListMIDlet() {excList = new List("EXCLUSIVE", Choice.EXCLUSIVE, new String[] {"Element1", "Element2", "Element3" }, null);mulList = new List("MULTIPLE", Choice.MULTIPLE, new String[] {"Element1", "Element2", "Element3" }, null);impList = new List("IMPLICIT", Choice.IMPLICIT, new String[] {"Element1", "Element2", "Element3" }, null);excList.addCommand(cmdMulList);excList.addCommand(cmdImpList);excList.addCommand(cmdExit);excList.setCommandListener(this);mulList.addCommand(cmdExcList);mulList.addCommand(cmdImpList);mulList.addCommand(cmdExit);mulList.setCommandListener(this);impList.addCommand(cmdExcList);impList.addCommand(cmdMulList);impList.addCommand(cmdExit);impList.setCommandListener(this);}protected void destroyApp(boolean arg0) {// TODO Auto-generated method stub}protected void pauseApp() {// TODO Auto-generated method stub}protected void startApp() throws MIDletStateChangeException {display = Display.getDisplay(this);display.setCurrent(excList);}public void commandAction(Command command, Displayable displayable) {if (command.equals(cmdExcList)) {display.setCurrent(excList);} else if (command.equals(cmdImpList)) {display.setCurrent(impList);} else if (command.equals(cmdMulList)) {display.setCurrent(mulList);} else if (command.equals(cmdExit)) {this.notifyDestroyed();this.destroyApp(true);}}}