Damon's Modern Life

To celebrate my new purchase for a Google Nexus One – I’ve started looking into Android development.

Android is built in Java and since I studied Java at University I decided to have a little play.  From experience of using Android there are times when on screen messages pop up for whatever reason.  In Android these are called Toast.

I’ve included a full class which explains how these Toast Objects are created.  If you’re just interested in getting a Toast message to appear then the following code will work for you.

// Create a piece of toast.
Toast pieceToast = Toast.makeText(getApplicationContext(), toastText.getText(), Toast.LENGTH_SHORT);

// Show the toast.
pieceToast.show();

The following class is a complete application albeit a very small one. Its purpose is to display a text field which allows the user to enter text and button which will show a Toast message.

/**
 * This is a Android example to which shows how to display a piece of toast.
 * Makes use of OnClickListener interface
 *
 * @author Damon Skelhorn 
 */

package com.damon86.toastExample;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.Toast;

public class ToastExample extends Activity implements OnClickListener {
    /** Called when the activity is first created. */

	// The text and button used on the display.
	EditText toastText = null;
	Button showToast = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Create a new Layout.
        LinearLayout rootLayout = new LinearLayout(getApplicationContext());

        // Create textfield
        toastText = new EditText(getApplicationContext());
        toastText.setText("Hello Toast!");

        // Create button and set OnClickListener
        showToast = new Button(getApplicationContext());
        showToast.setText("Show Toast");
        showToast.setOnClickListener(this);

        // Add components to the Layout.
        rootLayout.addView(toastText);
        rootLayout.addView(showToast);

        // Add the layout as the content view for the application.
        setContentView(rootLayout);
    }

    /**
     * Implemented method - onClick.
     * Show the user a piece of toast.
     */
	@Override
	public void onClick(View v) {

		// Create a piece of toast.
		Toast pieceToast = Toast.makeText(getApplicationContext(), toastText.getText(), Toast.LENGTH_SHORT);

		// Show the toast.
		pieceToast.show();
	}
}

The class implements the OnClickListener Interface. For those who do not know what an interface is, its a absract type which contains a set of empty methods know as method signatures. When a class implements a interface, Java expects your class to contain these methods. You can then write any code within these methods.

To make sure the button executes the code contained in the onClick method, the onClickListener is set on the button by using the following code;

showToast.setOnClickListener(this);

Download complete ToastExample Project

This entry was posted on Monday, January 18th, 2010 at 7:29 pm and is filed under Android, Java. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.