Android ProgressBar Example.

ProgressBar View 

* The ProgressBar view provides visual feedback of some ongoing tasks, such as when you are per- forming a task in the background.

* For example, you might be downloading some data from the Web and need to update the user about the status of the download.

* In this case, the ProgressBar view is a good choice for this task.


1 . Using Eclipse, create an Android project and name it as ProgressBarView. 

2 . Modify the main.xml file located in the res/layout folder by adding the following code in bold: 

<?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" >
   
 <ProgressBar android:id="@+id/progressbar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        style="?android:attr/progressBarStyleHorizontal" />
       
</LinearLayout>

3 . In the MainActivity.java file, add the following statements in bold:

package com.emergingandroidtech.ProgressBarView;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.ProgressBar;

public class MainActivity extends Activity {
   
    private static int progress;
    private ProgressBar progressBar;
    private int progressStatus = 0;
    private Handler handler = new Handler();
       
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        progress = 0;
        progressBar = (ProgressBar) findViewById(R.id.progressbar);
        progressBar.setMax(200);
       
        //---do some work in background thread---
        new Thread(new Runnable()
        {

            public void run()
            {
                //---do some work here---
                while (progressStatus < 200)
                {
                    progressStatus = doSomeWork();
                    //---Update the progress bar---
                    handler.post(new Runnable()
                    {
                        public void run() {
                            progressBar.setProgress(progressStatus);
                        }
                    });
                }

                //---hides the progress bar---
                handler.post(new Runnable()
                {
                    public void run()
                    {
                        //---0 - VISIBLE; 4 - INVISIBLE; 8 - GONE---
                        progressBar.setVisibility(8);
                    }
                });
            }   

            //---do some long lasting work here---
            private int doSomeWork()
            {
                try {
                    //---simulate doing some work---
                    Thread.sleep(50);
                } catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
                return ++progress;
            }
        }).start(); 
    }
}

4 . It shows the ProgressBar animating. After about five seconds, it will disappear.