Simulate Animation, using Runnable Thread

After the articles, Display a drawable graph, using ImageView and AndroidRunnable, with Runnable Thread, now we can try to simulate animation using setImageResource(), inside handleMessage() which are trigged by a Runnable Thread. A circle arrow rotate in duration of 1000ms.

This exercise extends from the previous article, AndroidRunnable, with Runnable Thread.




Save the four graphics, used to form the animation of a rotating arrow, in the /res/drawable/ folder.



Add a ImageView in main.xml to display the animation.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   >
<TextView 
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/hello"
   />
<TextView 
   android:id="@+id/i"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   />
<ImageView
   android:id="@+id/myImageView"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:scaleType="center"
   />
</LinearLayout>

Modify update_i() to change i, and load ViewImage with arrow_01, arrow_02, arrow_03 and arrow_04 one by one.

package com.exercise.AndroidRunnable;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
import android.widget.TextView;

public class AndroidRunnable extends Activity{
 
 int i = 0;
 TextView myi;
 ImageView MyImageView;
 
 Handler handler = new Handler(){

  @Override
  public void handleMessage(Message msg) {
   // TODO Auto-generated method stub
   update_i();
  }
 };
 
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

myi =(TextView)findViewById(R.id.i);
MyImageView = (ImageView)findViewById(R.id.myImageView);
}

@Override
 protected void onStart() {
  // TODO Auto-generated method stub
  super.onStart();
  
  Thread myThread=new Thread(new Runnable() {
   public void run() {
    while(true){
     try {
      handler.sendMessage(handler.obtainMessage());
      Thread.sleep(1000);
     }
     catch (Throwable t) {
     }
    }
   }
  });
   
  myThread.start();
 }

 private void update_i()
{
 switch(i){
 case 0:
  i++;
 MyImageView.setImageResource(R.drawable.arrow_01);
  break;
 case 1:
  i++;
 MyImageView.setImageResource(R.drawable.arrow_02);
  break;
 case 2:
  i++;
 MyImageView.setImageResource(R.drawable.arrow_03);
  break;
 case 3:
  i = 0;
 MyImageView.setImageResource(R.drawable.arrow_04);
  break;
 }
 myi.setText(String.valueOf(i));
}
}

AndroidRunnable.java can be downloaded here.

For sure, it's not a good practice to implement animation. It is used to show the implementation of Runnable Thread, and Handle.

Here is another article about Animation background, using animation-list and AnimationDrawable.