Introduction to Android Development (i) detailed activities 1.5 Show progress dialog box

When you want to do time-consuming operations, you will often see a dialog box with the words "Please wait". For example, users are logging on to a server that does not allow users to use the software at this time, or when the application returns the results to the user, for some time-consuming calculations. In these cases, a "Progress bar" dialog box is displayed, which allows the user to wait in a friendly way, while also preventing users from doing some unnecessary actions.

1. Create a project: Dialog.

2. Code in the Main.xml.

<?xml version= "1.0" encoding= "Utf-8"?> <linearlayout xmlns:android=     
"http://schemas.android.com/" Apk/res/android " 
    android:layout_width=" fill_parent " 
    android:layout_height=" fill_parent " 
    android:o" rientation= "vertical" >     
         
    <button     
        android:id= "@+id/btn_dialog2" android:layout_width= "Fill_" 
        Parent " 
        android:layout_height=" wrap_content " 
        android:onclick=" OnClick2 " 
        android:text=" click to Display a progress Dialog "/>     
         
</LinearLayout>

3. Code in the Dialogactivity.java.

public class Dialogactivity extends activity {ProgressDialog progressdialog; /** called the activity is a.     
        * * @Override public void onCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate);     
    Setcontentview (R.layout.main); public void OnClick2 (View v) {//---Show the dialog---final progressdialo     
        G Dialog = Progressdialog.show (this, "doing something", "Please wait ...", true); New Thread (New Runnable () {public void run () {try {//-     
                    -simulate doing something lengthy---thread.sleep (5000);     
                ---Dismiss the dialog---dialog.dismiss ();     
                catch (Interruptedexception e) {e.printstacktrace ();     
  }          }). Start (); }     
}

4. Press F11 to debug, click on the button, pop-up "Progress bar" dialog box.

Basically, to create a progress bar dialog box, just create an instance of the ProgressDialog class, and then call the show () method:

---Show the dialog---     
final progressdialog dialog = Progressdialog.show (this,     
        doing something, " ... ", true);

Because it's a "modal" dialog, it hides other UI components until it is released. If you want to perform a "long-running" task in the background, you can create a thread. The code inside the Run () method will be executed in a separate thread. The following code uses the Sleep () method to simulate a background task that takes 5 seconds to perform:

New Thread (New Runnable () {public     
    void run () {     
        try {     
            //---simulate doing something lengthy---     
            thread.sl EEP (5000);     
            ---Dismiss the dialog---     
            dialog.dismiss ();)     
        catch (Interruptedexception e) {     
            e.printstacktrace ();     
        }     
    }     
). Start ();

After 5 seconds, the dismiss () method is executed, and the dialog box is removed.

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