Java Tips - How to implement a textbox in a mobile game

A method of implementing a Textbox in a moble game is presented in this tip. TextBox is a component used to display and modify text. Since it is derived from Screen, TextBox occupies the entire screen of the device and therefore can accomodate relatively large amounts of text spread over several lines.


import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.IOException;

import javax.microedition.lcdui.Display;

import javax.microedition.lcdui.TextBox;

import javax.microedition.lcdui.TextField;

import javax.microedition.lcdui.Ticker;

import javax.microedition.midlet.MIDlet;



public class TextBoxMIDlet extends MIDlet {

    

    // Maximum size of the text in the TextBox

    private static final int MAX_TEXT_SIZE = 64;

    

    // The TextBox

    protected TextBox textBox;

    

    // The MIDlet's Display object

    protected Display display;

    

    // Flag indicating first call of startApp

    protected boolean started;

    

    protected void startApp( ) {

        

        if (!started) {

    

            // First time through - initialize

            // Get the text to be displayed

            String str = null;

            

            try {

            

                InputStream is = getClass( ).getResourceAsStream(

                        "resources/text.txt");

                

                InputStreamReader r = new InputStreamReader(is);

                char[] buffer = new char[32];

                StringBuffer sb = new StringBuffer( );

                int count;

                

                while ((count = r.read(buffer, 0, buffer.length)) > -1) {

                    sb.append(buffer, 0, count);

                }

                

                str = sb.toString( );

                

            } catch (IOException ex) {

                str = "Failed to load text";

            }

            

            // Create the TextBox

            textBox = new TextBox("TextBox Example", str,

                    MAX_TEXT_SIZE, TextField.ANY);

            

            // Create a ticker and install it

            Ticker ticker = new Ticker("This is a ticker...");

            textBox.setTicker(ticker);

            

            // Install the TextBox as the current screen

            display = Display.getDisplay(this);

            display.setCurrent(textBox);

            started = true;

        }

    }

    

    protected void pauseApp( ) {

        

    }

    

    protected void destroyApp(boolean unconditional) {

        

    }

    

}

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