當我們需要再移動設備上輸入數據時，TextBox 就派上用場了，我們使用的TextBox 構造函數參數共有四個，TextBox textbox = new TextBox(string title, string content, string maxLength, string limitType) ，第一個是標題，第二個是TextBox 的初始內容，第三個是允許輸入字符的最大長度，第四個是限制內型。值得注意的是：一個TextBox 必須附加一個命令，否則用戶將不能激發任何行為，而陷入這個TextBox 中。
下面是一個常見的TextBox 的例子。
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/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.thinkrace.TextBox;
import javax.microedition.lcdui.Choice;
import javax.microedition.lcdui.ChoiceGroup;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.TextBox;
import javax.microedition.lcdui.TextField;
import javax.microedition.lcdui.Ticker;
import javax.microedition.midlet.*;
/**
* @author pengjw
*/
public class TextBoxDemo extends MIDlet implements CommandListener{
private Display display;
private ChoiceGroup types;
private ChoiceGroup options;
private Form mainForm;
private static final Command CMD_EXIT = new Command("Exit", Command.EXIT, 1);
private static final Command CMD_BACK = new Command("Back", Command.BACK, 1);
private static final Command CMD_SHOW = new Command("Show", Command.SCREEN ,1);
private static final String[] textBoxLabels ={
"Any Character", "Email", "Number", "Decimal", "Phone", "URL"
};
private static final int[] textBoxTypes ={
TextField.ANY, TextField.EMAILADDR, TextField.NUMERIC,
TextField.DECIMAL, TextField.PHONENUMBER, TextField.URL
};
//firstTime用來判斷TextBoxDemo是否被實例化
private boolean firstTime;
public TextBoxDemo(){
/**
* 來自文檔的說明
* Display represents the manager of the display and input devices of the system.
* It includes methods for retrieving properties of the device and for requesting that objects be displayed on the device.
* There is exactly one instance of Display per MIDlet and the application can get
* a reference to that instance by calling the getDisplay() method.
*/
display = Display.getDisplay(this);
firstTime = true;
}
public void startApp() {
if(firstTime){
mainForm = new Form("Select a Text Box Type");
mainForm.append("select a textbox type");
types = new ChoiceGroup("Choice Type", Choice.EXCLUSIVE, textBoxLabels, null);
mainForm.append(types);
String[] optionStrings = {"As Password", "Show Ticker"};
options = new ChoiceGroup("Options", Choice.MULTIPLE, optionStrings, null);
mainForm.append(options);
mainForm.addCommand(CMD_EXIT);
mainForm.addCommand(CMD_SHOW);
mainForm.setCommandListener(this);
firstTime = false;
}
//設置當前顯示的窗體
display.setCurrent(mainForm);
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
/**
* 實現CommandListener接口的抽象方法
* 根據不同的Command做不同的事情
*/
public void commandAction(Command c, Displayable d) {
if(c == CMD_EXIT){
destroyApp(false);
notifyDestroyed();
}
else if(c == CMD_SHOW){
int Index = types.getSelectedIndex();
String title = textBoxLabels[Index];
int choiceType = textBoxTypes[Index];
boolean[] flags = new boolean[2];
/**
* 來自文檔的說明，這個方法可以給一個bool數組賦值
* Query the state of a choicegroup and renturns the state of all elements in the boolean array.
*/
options.getSelectedFlags(flags);
if(flags[0]){
choiceType = TextField.PASSWORD;
}
TextBox textBox = new TextBox(title,"",50,choiceType);
if(flags[1]){
textBox.setTicker(new Ticker("TextBox:" + title));
}
textBox.addCommand(CMD_BACK);
textBox.setCommandListener(this);
display.setCurrent(textBox);
}
else if(c == CMD_BACK){
display.setCurrent(mainForm);
}
}
}
附上兩張效果圖：
