CheckBox component in Echo3

Some of the very useful components that are common in any application development are CheckBox, ListBox, Button and RadioButton. Here in this Check Box example we will describe you how to create CheckBox component in Echo3. We have used here the server-side API to create checkbox. CheckBox class can be found in the nextapp.echo.app package.

There are four constructor of the class CheckBox as follows:

CheckBox() default constructor, will create a simple checkbox without any label
CheckBox(ImageReference icon) will creates a check box with an icon
CheckBox(java.lang.String text) will creates a check box with label
CheckBox(java.lang.String text, ImageReference icon) it will creates a check box with label and an icon

To create CheckBox application in Echo3 we have created two java files as described below:

CheckBoxServlet.java
CheckBoxApp.java

CheckBoxServlet.java extends the WebContainerServlet and is responsible for creating a new application instance and returns a new instance of CheckBoxApp. We have created a grid here and have added two check box items into it. On the first check box object we have added the action listener and on another check box is simple without any action. Following is the full example code of our application as follows:

CheckBoxServlet.java


package check;



import nextapp.echo.app.ApplicationInstance;

import nextapp.echo.webcontainer.WebContainerServlet;



public class CheckBoxServlet extends WebContainerServlet{



  public ApplicationInstance newApplicationInstance(){

  return new CheckBoxApp();

  }

}

CheckBoxApp.java


package check;



import nextapp.echo.app.ApplicationInstance;

import nextapp.echo.app.ContentPane;

import nextapp.echo.app.Label;

import nextapp.echo.app.Window;

import nextapp.echo.app.*;



import nextapp.echo.app.event.*;



public class CheckBoxApp extends ApplicationInstance {

  

  private ContentPane contentPane;

  private CheckBox check1;

  private CheckBox check2;

  private Grid grid;

  private Window window;

  private WindowPane windowPane;



  public Window init() {

  window = new Window();

  contentPane = new ContentPane();

  grid = new Grid();

  windowPane = new WindowPane();

  windowPane.add(new Label("CheckBox Example"));

  check1 = new CheckBox("Check Box with action");

  check2 = new CheckBox("Check Box without action");

  grid.setBorder(new Border(2,Color.BLUE,Border.STYLE_SOLID));

  grid.add(check1);

  grid.add(check2);

 check1.addActionListener(new ActionListener() {

  public void actionPerformed(ActionEvent e)

  {

  windowPane.setTitle("Check Box");

  contentPane.add(windowPane);

  }

 });

 contentPane.add(grid);

 window.setContent(contentPane);

  return window;

 }  

}

Output:

Download Project Source Code

CheckBox component in Echo3