byteToHexString

public class Main {
public static void main(String[] args) {
System.out.print(byteToHexString("abcde".getBytes()));
}

public static String byteToHexString(byte[] b) {
char[] digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
StringBuffer sb = new StringBuffer();
for (byte i : b) {
sb.append(digit[((i & 0xF0) >> 4)]);
sb.append(digit[i & 0x0F] + " ");
}
return sb.toString();
}
}



output:
61 62 63 64 65

날짜 표현 DateFormat, Custom Date Text View

Date today;
String output;
SimpleDateFormat formatter;

formatter = new SimpleDateFormat(pattern, currentLocale);
today = new Date();
output = formatter.format(today);
System.out.println(pattern + " " + output);

Customized Date and Time Formats

Pattern	Output
dd.MM.yy	30.06.09
yyyy.MM.dd G 'at' hh:mm:ss z	2009.06.30 AD at 08:29:36 PDT
EEE, MMM d, ''yy	Tue, Jun 30, '09
h:mm a	8:29 PM
H:mm	8:29
H:mm:ss:SSS	8:28:36:249
K:mm a,z	8:29 AM,PDT
yyyy.MMMMM.dd GGG hh:mm aaa	2009.June.30 AD 08:29 AM

Custom Date Text View

public class MDateView extends View {
 private final static String FORMAT_DEFULAT = "yyyy.MM.dd";

 private boolean isTickable = false;
 private boolean isColon = true;
 private Calendar mCalendar;
 private Runnable mTickerRunnable;
 private Handler mHandler;
 private String mFormat = FORMAT_DEFULAT;
 private String mDateString = "", mTimeString = "";
 private Paint mDatePaint, mTimePaint;

 public MDateView(Context context) {
  super(context);
  initClock(context);
 }

 public MDateView(Context context, AttributeSet attrs) {
  super(context, attrs);
  initClock(context);
 }

 private void initClock(Context context) {
  if (mCalendar == null) {
   mCalendar = Calendar.getInstance();
  }

  mDatePaint = new Paint(Paint.ANTI_ALIAS_FLAG);

  mDatePaint.setColor(Color.argb(255, 255, 255, 255));
  mDatePaint.setTextSize(18);
  mDatePaint.setTextAlign(Align.LEFT);

  mTimePaint = new Paint(Paint.ANTI_ALIAS_FLAG);

  mTimePaint.setColor(Color.argb(255, 255, 255, 255));
  mTimePaint.setTextSize(24);
  mTimePaint.setTextAlign(Align.LEFT);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  canvas.drawText(mDateString, 5, 35, mDatePaint);

  int offsetX = 92;
  float time_X_Pos = (120 - mTimePaint.measureText(mTimeString, 0, mTimeString.length())) / 2.0f;// center align
  canvas.drawText(mTimeString, offsetX + time_X_Pos, 35, mTimePaint);

 }

 @Override
 protected void onAttachedToWindow() {
  super.onAttachedToWindow();
  isTickable = true;
  mHandler = new Handler();

  mTickerRunnable = new Runnable() {
   public void run() {
    if (!isTickable)
     return;

    mCalendar.setTimeInMillis(System.currentTimeMillis());
    mDateString = DateFormat.format(mFormat, mCalendar).toString();
    mTimeString = DateFormat.format("k" + (isColon ? ":" : " ") + "mm", mCalendar).toString();
    invalidate();

    long now = SystemClock.uptimeMillis();
    long next = now + (1000 - now % 1000);
    isColon = !isColon;
    mHandler.postAtTime(mTickerRunnable, next);
   }
  };
  mTickerRunnable.run();
 }

 @Override
 protected void onDetachedFromWindow() {
  super.onDetachedFromWindow();
  isTickable = false;
 }

 public void setFormat(String format) {
  if (mFormat == format)
   return;
  mFormat = format;
 }

기기의 DPI 확인

DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
Log.d("TEST", "DPI = " + displayMetrics.densityDpi);

android(java) 파일 저장 후 리부팅 시 저장안되어 있는 현상

android에서 FileOutputStream 의 write();,  flush(); 했는데도 리부팅 시 간헐적으로 파일이 생성되지 않았거나 파일 내 데이터가 변하지 않을 때가 있다.

FileOutputStream 의 flush(); 가 버퍼를 비우는 기능만 수행하고 실제 physical device에 데이터를 저장하지 않아 파일에 데이터를 쓰기까지의 딜레이가 생기는 것이다.

이 때 fos.getFD().sync();의 메서드로 파일시스템 내부의 캐쉬를 모두 physical device로 저장한다.



FileOutputStream fos = this.openFileOutput(filename, Context.MODE_PRIVATE);
fos.write(obj.toString().getBytes());
fos.flush();
fos.getFD().sync();
fos.close();

Shuffle 기능

 List< Integer > numbers;
Collections.shuffle( numbers );

// 0부터 6번째 인덱스 데이터 가지고 옴
        List< Integer > winningCombination = numbers.subList( 0 , 6 );

// 정렬
Collections.sort( winningCombination );

TextView 왼쪽 아이콘

android:drawableLeft="@drawable/ic_launcher"

or

TextView tv; 
Drawable icon; 


Bitmap b = Bitmap.createScaledBitmap(((BitmapDrawable) icon).getBitmap(), 120, 120, false);
icon = new BitmapDrawable(b); 
icon.setBounds(0, 0, icon.getIntrinsicWidth(), icon.getIntrinsicHeight());

tv.setTextSize(12); 
tv.setGravity(Gravity.CENTER); 
tv.setCompoundDrawables(icon, null, null, null);

GPS 관련

LocationManager
위치 기반 서비스를 관리하는 Class
Location
위치 정보를 가지고있는 Class
LocationPovider
위치를 결정하는데 사용되는 공급자를 지정.
위치 공급자 식별자
LocationManager.GPS_PROVIDER
LocationManager.NETWORK_PROVIDER
LocationListener
위치 갱신에 따른 위치 정보를 수신할 수 있는 Listener Interface
Permission
ACCESS_FINE_LOCATION - 정밀한위치를가져온다.
ACCESS_COARSE_LOCATION - 낮은정밀도의위치를가져온다.

서비스 바인드와 핸들러 구현 (옵저버 패턴)

//// mActivity.java  
Messenger mService = null;  
boolean bindService = false;

class IncomingHandler extends Handler {
    @Override  
    public void handleMessage(Message msg) {

    }  
}  

final Messenger mMessenger = new Messenger(new IncomingHandler());

private ServiceConnection mConnection = new ServiceConnection() {
    public void onServiceConnected(ComponentName className, IBinder service) {

        mService = new Messenger(service);  

        try {  
            Message msg = Message.obtain(null, MessengerService.MSG_REGISTER_CLIENT);
            msg.replyTo = mMessenger;  
            mService.send(msg);  

        } catch (RemoteException e) {  
          
        }  
    }  

    public void onServiceDisconnected(ComponentName className) {

        mService = null;  
    }  
};  

void doBindService() {  
    // Establish a connection with the service. We use an explicit
    // class name because there is no reason to be able to let other
    // applications replace our component.  
    bindService = getApplicationContext().bindService(new Intent(mActivity.this, MessengerService.class), mConnection, Context.BIND_AUTO_CREATE);  

}  

void doUnbindService() {  
    if (bindService) {  
        // If we have received the service, and hence registered with it, then now is the time to unregister. 
        if (mService != null) {
            try {  
                Message msg = Message.obtain(null, MessengerService.MSG_UNREGISTER_CLIENT);
                msg.replyTo = mMessenger;  
                mService.send(msg);  
            } catch (RemoteException e) {  
                // There is nothing special we need to do if the service has crashed. 
            }  
        }  

        // Detach our existing connection.  
        getApplicationContext().unbindService(mConnection);  
        bindService = false;  
    }  
}  


////MessengerService.java  

     
    /** 
     * Command to the service to register a client, receiving callbacks 
     * from the service.  The Message's replyTo field must be a Messenger of 
     * the client where callbacks should be sent. 
     */ 
    public final static int MSG_REGISTER_CLIENT = 1;
    /** 
     * Command to the service to unregister a client, ot stop receiving callbacks 
     * from the service.  The Message's replyTo field must be a Messenger of 
     * the client as previously given with MSG_REGISTER_CLIENT. 
     */ 
    public final static int MSG_UNREGISTER_CLIENT = 2;
    /** 
     * Command to service to set a new value.  This can be sent to the 
     * service to supply a new value, and will be sent by the service to 
     * any registered clients with the new value. 
     */ 
    static final int MSG_SET_VALUE = 3;

    ArrayList<Messenger> mClients = new ArrayList<Messenger>(); 

    private final Messenger mMessenger = new Messenger(new IncomingHandler());

    private class IncomingHandler extends Handler {
        @Override 
        public void handleMessage(Message msg) {
            switch (msg.what) { 
            case MSG_REGISTER_CLIENT: 
                mClients.add(msg.replyTo); 
                break; 
            case MSG_UNREGISTER_CLIENT: 
                mClients.remove(msg.replyTo); 
                break; 
            } 
        } 
    } 

    @Override 
    public IBinder onBind(Intent intent) { 
        return mMessenger.getBinder(); 
    } 

    /** 
     * Send Message to Clients. 
     * @param msg Message 
     */ 
    private void sendMessageToClients(Message msg) {
        for (int i = mClients.size() - 1; i >= 0; i--) { 
            try { 
                // send a message to mClients. 
                // you may have handle this massage from IncomingHandler at any Activity
                mClients.get(i).send(msg); 
            } catch (RemoteException e) { 
                // The client is dead. Remove it from the list; 
                // we are going through the list from back to front
                // so this is safe to do inside the loop. 
                mClients.remove(i); 
            } 
        } 
    }

Home Launcher 등록

<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
 </intent-filter>

어두워짐 방지 (screen full wake up)

PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.ACQUIRE_CAUSES_WAKEUP | PowerManager.SCREEN_BRIGHT_WAKE_LOCK, "screen"); 
wl.acquire(); 
//     ..screen will stay on during this section.. 
//wl.release();

<uses-permission android:name="android.permission.WAKE_LOCK"/>

Create Thread

1.

    class mThread extends Thread {
        @Override 
        public void run() {
             
             
        } 
    } 
     
     
    mThread t = new mThread(); 
    t.start();

2.

Thread thread = new Thread(){
 @Override
 public void run() {
  // TODO Auto-generated method stub
 }
};

Timer

    // 타미어 테스크 정의     
    TimerTask mTask = new TimerTask() { 
        @Override 
        public void run() {
            // do something!! 
        } 
    }; 
     
     
    // 사용 
    Timer mTimer = new Timer(); 
    mTimer.schedule(mTask, WHEN, PERIOD);

Start Activity When Boot Completed

public class mReceiver extends BroadcastReceiver {

    @Override 
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)) {
            Log.d("tag", "boot ok"); 
            Intent i = new Intent(context, sampleActivity.class); 
            i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 
            context.startActivity(i); 
        } 
    } 
}

Need Uses Permission : android.permission.RECEIVE_BOOT_COMPLETED

edittext 특수문자 제한, 한글만 입력

// 영문 + 숫자 
public InputFilter filterAlphaNum = new InputFilter() {
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        Pattern ps = Pattern.compile("^[a-zA-Z0-9]*$"); 
        if (!ps.matcher(source).matches()) { 
            return ""; 
        } 
        return null; 
    } 
}; 

// 한글 
public InputFilter filterKor = new InputFilter() {
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        Pattern ps = Pattern.compile("^[ㄱ-ㅣ가-힣]*$"); 
        if (!ps.matcher(source).matches()) { 
            return ""; 
        } 
        return null; 
    } 
}; 


editText.setFilters(new InputFilter[]{filterAlphaNum}); 

패키지 정보 가져오기

ArrayList<PackageInfo> packages = new ArrayList<PackageInfo>(); 
PackageManager pm; 

void getPackeges() { 
    pm = (PackageManager) this.getPackageManager(); 
    List<PackageInfo> allPackages = pm.getInstalledPackages(PackageManager.GET_PERMISSIONS);

    for (int i = 0; i < allPackages.size(); i++)
        if (!isSystemApplication(allPackages.get(i))) 
            packages.add(allPackages.get(i)); 
} 

boolean isSystemApplication(PackageInfo packinfo) { 
    return (packinfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0 ? true : false;
}

Install, Uninstall 소스

Uri uri = Uri.fromParts("package", packageName, null);    
Intent i = new Intent(Intent.ACTION_DELETE, uri);    
startActivity(i);

Uri uri= Uri.fromParts("package", packageName , null); 
Intent i = new Intent(Intent.ACTION_PACKAGE_ADDED, uri); 
startActivity(i);

터치 좌표, 터치 다운 이벤트

button.setOnTouchListener(new OnTouchListener() { 
    @Override 
    public boolean onTouch(View v, MotionEvent event) {
        float x = event.getX(); 
        float y = event.getY(); 
        switch (event.getAction()) { 
        case MotionEvent.ACTION_DOWN: 

            break; 
        case MotionEvent.ACTION_UP: 
        } 
        return pressed; 
    } 
});

screen capture

public void screenshot(View view) throws Exception {

    view.setDrawingCacheEnabled(true); 
    Bitmap screenshot = Bitmap.createBitmap(view.getDrawingCache()); 
    view.setDrawingCacheEnabled(false); 

    if (screenshot == null) { 
        Log.e("screencast", "error : could not get drawing cache..."); 
        return; 
    } 

    File dir = Environment.getExternalStorageDirectory(); 
    String baseName = "screencast"; 
    String extention = ".jpg"; 
    String filename = baseName + extention; 

    try { 
        File f = new File(dir, filename); 
        f.createNewFile(); 

        OutputStream outStream = new FileOutputStream(f); 

        screenshot.compress(Bitmap.CompressFormat.JPEG, 80, outStream);
        outStream.flush(); 
        outStream.close(); 

        Log.d("screencast", "captured to " + f.getPath() + "(" + f.length() + "byte)"); 

    } catch (IOException e) { 
        e.printStackTrace(); 
    } 
}

StartActivity, StartService

Intent i = new Intent(currentActivity.this, targetActivity.class); 
startActivity(i); 


Intent i = new Intent(currentActivity.this, targetService.class);
startService(i);

Button setOnclickListener

button.setOnClickListener(new OnClickListener() { 
    public void onClick(View v) {
       

    } 
});