進度對話框(ProgressDialog)

本範例示範如何實現進度對話框(ProgressDialog), 通過異步任務(AsyncTask)啟動和關閉進度對話框.



啟動進度對話框:
ProgressDialog.show();

關閉進度對話框:
progressDialog.dismiss();

main.xml

<?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:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<Button
    android:id="@+id/start"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="- Start -"
    />
</LinearLayout>

AndroidProgressDialog.java

package com.AndroidProgressDialog;

import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.widget.Button;

public class AndroidProgressDialog extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button buttonStart = (Button)findViewById(R.id.start);
        
        buttonStart.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub
    new asyncTaskUpdateProgress().execute();
   }
         
        });
        
    }
    
    public class asyncTaskUpdateProgress extends AsyncTask<Void, Integer, Void> {

     int progress;
     ProgressDialog progressDialog;
     
  @Override
  protected void onPostExecute(Void result) {
   // TODO Auto-generated method stub
   progressDialog.dismiss();
  }

  @Override
  protected void onPreExecute() {
   // TODO Auto-generated method stub
   progress = 0;
   progressDialog = ProgressDialog.show(AndroidProgressDialog.this, "ProgressDialog", "Wait!");
  }

  @Override
  protected Void doInBackground(Void... arg0) {
   // TODO Auto-generated method stub
   while(progress<100){
    progress++;
    SystemClock.sleep(20); 
   }
   return null;
  }
    }
}