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:
Progress Bar Test Layout

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:
Progress Bar Updating

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);
        }
    };
}

Mylearning

Wednesday, 12 October 2011

progressbar based on increment in android

Simple test layout

Updating the progress bar

Complete Java code

progressbar