progressbar based on increment in android

Android Progress Bar and Thread updating

11.04.2010

The progress bar is useful for telling users that your Android Application is working on a task that might take a little longer than the usual tasks.
A progress bar is quit easy to make, which I have described here is the Dialog Boxes post here and I will therefor not go into details with this.

Simple test layout

I have created a simple test layout like this:

XML layout:

<?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:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Maximum value"></TextView>   <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="100" android:id="@+id/maximum"></EditText>   <TextView android:id="@+id/TextView01" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Increment by"></TextView>   <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="5" android:id="@+id/increment"></EditText>   <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Start" android:id="@+id/startbtn"></Button>   </LinearLayout>

There are two text fields. One to set the maximum value of the progress bar and one to set the increment value. When pushing the Start button a progress bar is displayed and in this example it will just update the progress bar every half a second (500ms) to demonstrate the result.

Updating the progress bar

To update the progress bar in the background, while something else is running the application has to use threads. I will be setting up a thread when the Start button is clicked. The thread will then execute some code, in this case just a simple handler that will update the progress bar, and when finished the thread will terminate itself.
When the Start button is activated the application will display a progress bar – I have set a maximum value of 200 and a increment value of 14:

Complete Java code

The complete java code looks like this. I have added comments in the code, so it should be self explanatory – if not just post a comment last on this page.

package huuah.progressthread;   import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.app.ProgressDialog;   public class progressthread extends Activity implements OnClickListener {     ProgressDialog dialog;     int increment;       @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);           Button startbtn = (Button) findViewById(R.id.startbtn);         startbtn.setOnClickListener(this);     }       public void onClick(View view) {           // get the increment value from the text box         EditText et = (EditText) findViewById(R.id.increment);         // convert the text value to a integer         increment = Integer.parseInt(et.getText().toString());           dialog = new ProgressDialog(this);         dialog.setCancelable(true);         dialog.setMessage("Loading...");         // set the progress to be horizontal         dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);         // reset the bar to the default value of 0         dialog.setProgress(0);           // get the maximum value         EditText max = (EditText) findViewById(R.id.maximum);         // convert the text value to a integer         int maximum = Integer.parseInt(max.getText().toString());         // set the maximum value         dialog.setMax(maximum);         // display the progressbar         dialog.show();           // create a thread for updating the progress bar         Thread background = new Thread (new Runnable() {            public void run() {                try {                    // enter the code to be run while displaying the progressbar.                    //                    // This example is just going to increment the progress bar:                    // So keep running until the progress value reaches maximum value                    while (dialog.getProgress()<= dialog.getMax()) {                        // wait 500ms between each update                        Thread.sleep(500);                          // active the update handler                        progressHandler.sendMessage(progressHandler.obtainMessage());                    }                } catch (java.lang.InterruptedException e) {                    // if something fails do something smart                }            }         });           // start the background thread         background.start();       }       // handler for the background updating     Handler progressHandler = new Handler() {         public void handleMessage(Message msg) {             dialog.incrementProgressBy(increment);         }     }; }