Android App Development 101 3rd tutorial; MediaPlayer Basics

In this tutorial, I will be be making a basic android media player which streams a mp3 file from a url. Just like previous tutorial, this app has two buttons, one to play the music and the second to stop the music, release the media player object and exit the app. Here is the code:

main.xml


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    >

    <Button
        android:id="@+id/Button1"
        android:layout_width="fill_parent"
        android:layout_height="50dp"
        android:text="Start"
        android:gravity="left|center"
        android:onClick="playMusic"/>
   
    <Button
        android:id="@+id/Button2"
        android:layout_width="fill_parent"
        android:layout_height="50dp"
        android:text="Stop"
        android:gravity="left|center"
        android:onClick="stopMusic"/>
 

</LinearLayout>

MediaBasic.java


package com.peshal.mediaplayerbasics;

import java.io.IOException;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;

public class MediaBasic extends Activity {
MediaPlayer ourmediaPlayer = new MediaPlayer();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);


}
public void playMusic(View view) {
String url="http://archive.org/download/testmp3testfile/mpthreetest.mp3";
ourmediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
ourmediaPlayer.setDataSource(url);
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

try {
ourmediaPlayer.prepare();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
ourmediaPlayer.start();

}
public void stopMusic(View view) {
ourmediaPlayer.stop();
ourmediaPlayer.release();
this.finish();

}

}

Android App Development 101 2nd tutorial; xml, buttons, toast, switch case statement

In this tutorial i will be using the xml attributes that i discussed in the last tutorial. The goal of this tutorial is to familiarize with with some of the key concepts that are very common in android app development. We will be making an app that displays two buttons and when these buttons are clicked, a toast message with show up corresponding to that button. Toast messages are used in android when we have to display some message quick. For instance "push back again to exit" is one common toast message. Here is our code:

main.xml


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    >

    <Button
        android:id="@+id/Button1"
        android:layout_width="fill_parent"
        android:layout_height="50dp"
        android:text="Button1"
        android:gravity="left|center"
        android:onClick="displayToast"/>
   
    <Button
        android:id="@+id/Button2"
        android:layout_width="fill_parent"
        android:layout_height="50dp"
        android:text="Button2"
        android:gravity="left|center"
        android:onClick="displayToast"/>
 

</LinearLayout>

Buttons.java


package com.peshal.testappbuttons;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Toast;

public class Buttons extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void displayToast(View view) {


switch(view.getId()) {
case R.id.Button1:
Toast.makeText(getApplicationContext(), "Button 1 is Pressed", Toast.LENGTH_SHORT).show();
break;
case R.id.Button2:
Toast.makeText(getApplicationContext(), "Button 2 is Pressed", Toast.LENGTH_SHORT).show();
break;
}
}


}

Android App Development 101 1st tutorial, Learning xml attributes

Xml's are huge in android. You can accomplish lots of things using just xmls from animations to layouts. Besides xml lets you create your layout without writing any java code and see how it looks on a emulator or an actual device. In this post i will be talking about some of the basic xml attributes. These attributes will be frequently used in upcoming tutorials.

android:id="@+id/uniqueid"

The ids should be unique for each object whether its a button, textView, imageView or videoView. Unique ids are important when we have to reference that particular object in our java class.

android:height="x" and android:width="x"
x= xdp, wrap_content, fill_parent etc

wrap_content as the name suggest wraps the object and fill_parent fills the whole layout.

android:gravity = "x"
x = top, bottom,center,left,right etc

gravity attribute is used to locate the object in the layout.

android:onClick ="yourMethod"

onClick is another important attribute. For eg a button is given an onClick attribute. What is does is when the user clicks on that button, it runs the method that was listed in the xml in your java class file.

android:text="yourtext"

android:background="your color"

your color can use various formats. I like using the html color codes. For eg white would be #FFFFFF

you can find other color codes here.

There are lot more attributes, i will explain those as they come along.