copy file

public static void copyFile(String originalFileName, String destFileName) 
            throws Exception {

        byte[] buffer = new byte[4096]; 
        int size = -1;

        FileInputStream fis = new FileInputStream(originalFileName); 
        FileOutputStream fos = new FileOutputStream(destFileName);

        while ((size = fis.read(buffer, 0, buffer.length)) != -1) { 
            fos.write(buffer, 0, size); 
        }

        fis.close(); 
        fos.close();

        fis = null; 
        fos = null;

    }

delete directory / Folder

public static void deleteDirectory( File dir )
{

    if ( dir.isDirectory() )
    {
        String [] children = dir.list();
        for ( int i = 0 ; i < children.length ; i ++ )
        {
         File child =    new File( dir , children[i] );
         if(child.isDirectory()){
             deleteDirectory( child );
             child.delete();
         }else{
             child.delete();

         }
        }
        dir.delete();
    }
}

packagename to label

final PackageManager pm = getApplicationContext().getPackageManager();
ApplicationInfo ai;
try {
   ai = pm.getApplicationInfo("呢度係packagename", 0);
} catch (final NameNotFoundException e) {
   ai = null;
}
final String applicationName = (String) (ai != null ? pm.getApplicationLabel(ai) : "(unknown)");

Android Activity生命週期 OnPause() -> OnStop(). OnReStart() -> OnStart() -> OnResume().onDestroy().OnCreate()

通過這個練習知道, 原來按下HOME按鈕離開應用程式, 和按下BACK按鈕或調用finish()方法離開應用程式是不相同的.

按下HOME按鈕離開應用程式, 會順序調用: OnPause() -> OnStop().
再次進入應用程式會調用: OnReStart() -> OnStart() -> OnResume().

按下BACK按鈕或調用finish()方法離開應用程式: OnPause() -> OnStop() -> onDestroy().
再次進入應用程式會調用: OnCreate() -> OnStart() -> OnResume().







package com.AndroidLifeCycle;

 

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.Toast;

 

public class AndroidLifeCycle extends Activity {

   /** Called when the activity is first created. */

   @Override

   public void onCreate(Bundle savedInstanceState) {

       super.onCreate(savedInstanceState);

       setContentView(R.layout.main);

       

       Button finish = (Button)findViewById(R.id.finish);

       finish.setOnClickListener(new Button.OnClickListener(){

 

   @Override

   public void onClick(View v) {

    // TODO Auto-generated method stub

    finish();

   }});

       

       Toast.makeText(this, "onCreate", Toast.LENGTH_LONG).show();

       

   }

 

 @Override

 protected void onDestroy() {

  // TODO Auto-generated method stub

  super.onDestroy();

  Toast.makeText(this, "onDestroy", Toast.LENGTH_LONG).show();

 }

 

 @Override

 protected void onPause() {

  // TODO Auto-generated method stub

  super.onPause();

  Toast.makeText(this, "onPause", Toast.LENGTH_LONG).show();

 }

 

 @Override

 protected void onRestart() {

  // TODO Auto-generated method stub

  super.onRestart();

  Toast.makeText(this, "onRestart", Toast.LENGTH_LONG).show();

 }

 

 @Override

 protected void onResume() {

  // TODO Auto-generated method stub

  super.onResume();

  Toast.makeText(this, "onResume", Toast.LENGTH_LONG).show();

 }

 

 @Override

 protected void onStart() {

  // TODO Auto-generated method stub

  super.onStart();

  Toast.makeText(this, "onStart", Toast.LENGTH_LONG).show();

 }

 

 @Override

 protected void onStop() {

  // TODO Auto-generated method stub

  super.onStop();

  Toast.makeText(this, "onStop", Toast.LENGTH_LONG).show();

 }

}