UI thread is the thread in which the components of an application will be executed by default. But there are some tasks which are usually executed in background ( eg : downloading files ). These background tasks are run with the help of threads in Android. These threads are called non-ui threads.
An important rule associated with UI thread and Non-UI thread is that, do not do any manipulation on UI from a non UI thread. In order to overcome this problem, we will use Handler in this application. The Handler will manage the communication from non-ui thread ( working thread ) to ui thread.
In this application, the MainActivity screen contains a toggle button. When the toggle button is “ON”, the progress bar starts to increment and when the toggle button is “OFF”, the progress bar stops its execution.
The same application, but implemented using AsyncTask object is discussed in the article titled “Updating ProgressBar status from a non-ui thread ( working thread ) using AsyncTask in Android“.
This application is developed in Eclipse ( 4.2.0 ) with ADT ( 20.0.3) and Android SDK ( R20.0.3 ) .
1. Create a new Android application project namely “ProgressBarDemo”
Figure 1 : New Android Application Project namely ProgressBarDemo
2. Design application launcher icon
Figure 2 : Design Application Launcher Icon
3. Create a blank activity to create a MainActivity class
Figure 3 : Create a blank Activity
4. Enter MainActivity details
Figure 4 : Enter MainActivity Details
5. Remove the Android’s support library from this project, if exists
By default Eclipse ( 4.2.0) adds Android Support Library to Android application project. For this application, we don’t need to use this support library. So the library file libs/android-support-v4.jar may be removed manually via ProjectExplorer by simply right click on the file and then clicking the menu item “delete”.
6. Update the file res/values/strings.xml
<resources>
<string name="app_name">ProgressBarDemo</string>
<string name="hello_world">Hello world!</string>
<string name="menu_settings">Settings</string>
<string name="title_activity_main">ProgressBar Demo</string>
</resources>
7. Update the layout file res/layout/activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ToggleButton
android:id="@+id/tgl_start"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<ProgressBar
android:id="@+id/progress_bar"
style="@android:style/Widget.ProgressBar.Horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@id/tgl_start"
tools:context=".MainActivity" />
<TextView
android:id="@+id/tv_button_status"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/progress_bar"
android:layout_centerHorizontal="true"
tools:context=".MainActivity" />
</RelativeLayout>
8. Update the class MainActivity in the file src/in/wptrafficanalyzer/progressbardemo/MainActivity.java
package in.wptrafficanalyzer.progressbardemo;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.Menu;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.ToggleButton;
public class MainActivity extends Activity {
private ProgressBar mProgressBar;
private Handler mHandler = new Handler();
private ToggleButton mTglStart;
private TextView mTvButtonStatus;
private int mProgressStatus = 0;
private Thread mThread;
private Runnable mRunnable;
private int mBtnStatus=0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mProgressBar = (ProgressBar) findViewById(R.id.progress_bar);
mTglStart = (ToggleButton) findViewById(R.id.tgl_start);
mTvButtonStatus = (TextView) findViewById(R.id.tv_button_status);
mTglStart.setChecked(false);
mTvButtonStatus.setText("Toggle Button is off");
mRunnable = new Runnable() {
@Override
public void run() {
while(mProgressStatus<100){
try{
/** Exit current thread, if button status is off */
if(mBtnStatus==0 ){
break;
}
/** Increment progressbar status by 1 */
mProgressStatus++;
/** Sleep this thread for 100 ms */
Thread.sleep(100);
}catch(Exception e){
Log.d("Wait Exception",e.toString());
}
/** For every increment, sent a message to UI thread to increment the progressbar */
mHandler.post(new Runnable() {
@Override
public void run() {
mProgressBar.setProgress(mProgressStatus);
}
}
);
}
mHandler.post(new Runnable() {
@Override
public void run() {
mTglStart.setChecked(false);
}
}
);
}
};
OnCheckedChangeListener listener = new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
/** Button is set to ON */
if(isChecked){
/** Button is on */
mBtnStatus=1;
/** Create a new thread */
mThread = new Thread(mRunnable);
if(mProgressStatus==100)
mProgressStatus=0;
/** Starts the new thread */
mThread.start();
mTvButtonStatus.setText("Toggle Button is on");
}else{ /** Button is set to OFF */
/** Button is OFF */
mBtnStatus=0;
mTvButtonStatus.setText("Toggle Button is off");
}
}
};
/** Setting an event handler for button on and off */
mTglStart.setOnCheckedChangeListener(listener);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
9. Screenshot of the application in execution
Figure 5 : Progress bar in execution
10. Download
11. Reference
http://developer.android.com/guide/index.html
I am George Mathew, working as software architect and Android app developer at wptrafficanalyzer.in
You can hire me on hourly basis or on project basis for Android applications development.
For hiring me, please mail your requirements to info@wptrafficanalyzer.in.
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store4js.blogspot.com
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Greetings,
I am refering the tutorial of yours from this link……http://wptrafficanalyzer.in/blog/updating-progressbar-status-from-a-non-ui-thread-working-thread-using-handler-in-android/
I have a problem. soon after the progress touches 100, the bar disappears.!! what can i do.
Thank you sir.
Happy New Year.
We have not coded to hide the progress bar in the article. Please check it out.
Thank you.