[程式] Android Programming Tips

• EditText - Set & Get Value

• EditText EditField = (EditText) findViewById(R.id.EditID);
  
  // Set Value
  EditField.setText(<String>);
  
  // Get Value
  String InputString = EditField.getText().toString();
  



• Change Activity with Intent

/*** In the Activity Now ***/

Int IntValueB, IntValue;
String StringValueB, StringValue;
...

Intent intentName = new Intent(ActivityNow.this, ActivityToChange.class);
// Method 1
Bundle extra = new Bundle();
extra.putString("varStrB", StringValueB);
extra.putInt("varIntB", StringValueB);
...
intentName.putExtra(extra); //

// Method 2
intentName.putExtra("varStr", StringValue);
intentName.putExtra("varInt", IntValue);
... //

startActivity(intentName);

/*** In the Activity to Change ***/

Int IntValueB, IntValue;
String StringValueB, StringValue;
...

Bundle extra = getIntent().getExtras();
StringValueB = extra.getString("varStrB");
IntValueB = extra.getInt("varIntB");
StringValue = extra.getString("varStr");
IntValue = extra.getInt("varInt");
...



• Broadcast (Default & Custom Actions)
  

  /*** Send Broadcast ***/
  
  public class TheActivity extends Activity {
      static  Intent  mBroadcastCustom, mBroadcastDefault;
      ...
  
      protected void onCreate(Bundle savedInstanceState) {
          mBroadcastCustom =
              new Intent("sowhat.practice.provider.ACTION_CLEAN");
          mBroadcastDefault =
              new Intent(Intent.ACTION_ALL_APPS);
          ...
      }
  
      // Somewhere in the class (could be in onCreate also)
      sendBroadcast(mBroadcastCustom);
      sendBroadcast(mBroadcastDefault);
  }

• /*** Receive Broadcast ***/
  
  public class TheOtherActivity extends Activity{
      
      // Setup for custom broadcast
      private static IntentFilter mFilterCustom = 
          new IntentFilter("sowhat.practice.provider.ACTION_CLEAN");
      private BroadcastReceiver mReceiverCustom =
          new BroadcastReceiver() {
          @Override
          public void onReceive(Context context, Intent intent) {
              ...
          }
      };
  
      // Setup for default broadcast
      private static IntentFilter mFilterDefault =
          new IntentFilter("Intent.ACTION_ALL_APPS");
      private BroadcastReceiver mReceiverDefault =
          new BroadcastReceiver() {
          @Override
          public void onReceive(Context context, Intent intent) {
              ...
          }
      };
  
      protected void onCreate(Bundle savedInstanceState) {
          // "Turn on" the broadcast receiver
          registerReceiver(mReceiverCustom, mFilterCustom);
          registerReceiver(mReceiverDefault, mFilterDefault);
          ...
      }    
  }



• onClickListener
  

  public class MainActivity extends Activity 
  implements View.OnClickListener{
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          ...
    
          // Method 1
          Button button1 = (Button) findViewById(R.id.button1);
          button1.setOnClickListener(new View.OnClickListener(){
              public void onClick(View view){
                  ...
              }
          });
    
          // Method 2
          Button button2 = (Button) findViewById(R.id.button2);
          button2.setOnClickListener(this);
    
          // Method 3
          Button button3 = (Button) findViewById(R.id.button3);
          button3.setOnClickListener(new Image_Listener(this));
      }
  
      // Method 2
      public void onClick(View v){
          ...
      }
   
      // Method 3
      class Image_Listener implements OnClickListener {
          private MainActivity activity;
    
          public Image_Listener(MainActivity activity) {
              this.activity = activity;
          }
    
          @Override
          public void onClick(View v) {
              ...
          }
      }
      
      ...
  }

  ps. The activity should implements View.OnClickListener if and only if using method 3.


• Toast

  import android.widget.Toast;
  ...
  // In activity
  Toast.makeText(getApplicationContext(), <string to show>, Toast.LENGTH_SHORT).show();
  // In fragment
  Toast.makeText(getActivity(), <string to show>, Toast.LENGTH_SHORT).show();
  

• Access activity variables from a fragment

  <Activity_class_name> xxx = (<Activity_class_name>) getActivity();
  yyy = xxx.<variable_name>;

• Hide input method (keyboard)

  // In fragment
  View view = inflater.inflate(R.layout.<layout_name>, null);
  InputMethodManager imm = (InputMethodManager)
          getActivity().getSystemService(Activity.INPUT_METHOD_SERVICE);
  imm.hideSoftInputFromWindow
          (view.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);



• Get class / package name
  

  // Not in the activity class
  String className = <class_name>.class.getName();
  // In the activity class
  String className = this.getClass().getName();
  String packageName = this.getPackageName();



• Parameters for adding fullscreen view by WindowManager
  

  WinowManager.LayoutParams mParams = new WindowManager.LayoutParams(
                  WindowManager.LayoutParams.MATCH_PARENT,
                  WindowManager.LayoutParams.MATCH_PARENT,
                  WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
                  WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN |
                  WindowManager.LayoutParams.FLAG_LAYOUT_INSET_DECOR,
                  PixelFormat.OPAQUE);
  

  o. FLAG_LAYOUT_IN_SCREEN + FLAG_LAYOUT_INSET_DECOR
  真正全螢幕。
  o. FLAG_FULLSCREEN
  不包含 status bar 位置。
  若後方 activity 隱藏 status bar，會在 status bar 位置看穿後方內容。
  o. FLAG_FORCE_NOT_FULLSCREEN
  不包含 status bar 位置。
  即使後方 activity 隱藏 status bar，也會強迫顯示，但 status bar 顏色依後方 activity 而定。


• Set portrait or landscape for view, disable auto-rotation
  

  WinowManager.LayoutParams params;
  params = new WindowManager.LayoutParams(...);
  params.screenOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT;
  or
  params.screenOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
  

  REF: http://stackoverflow.com/questions/14587085/how-can-i-globally-force-screen-orientation-in-android


• 設定鍵盤及其相關行為
  < 方法 1 - for activity >
  在 AndroidManifest.xml 中的 activity 宣告 android:windowSoftInputMode ，
  設定進入時是否顯示鍵盤 (stateXXX) 以及鍵盤出現時是否調整 layout (adjustXXX)
  REF:
  http://developer.android.com/guide/topics/manifest/activity-element.html#wsoft
  < 方法 2 - for alert dialog>
  alertDialog.getWindow().setSoftInputMode(
          WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN |
          WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
  REF:
  http://stackoverflow.com/questions/5622202/how-to-resize-alertdialog-on-the-keyboard-displayhttp://developer.android.com/reference/android/view/WindowManager.LayoutParams.html


• Parameters for adding fullscreen view by WindowManager
  

  // In xml
  <TextView
      android:id="@+id/status_bar_blank"
      android:layout_width="match_parent"
      android:layout_height="0dp" />
  
  // In java
  TextView statusBarBlank = (TextView) mFloatView.findViewById(R.id.status_bar_blank);
  statusBarBlank.getLayoutParams().height = getStatusBarHeight();
  statusBarBlank.setBackgroundColor(Color.BLACK);
  
  private int getStatusBarHeight() {
      final Display display = mWindowManager.getDefaultDisplay();
      if (display != null && display.getDisplayId() != Display.DEFAULT_DISPLAY) {
          return 0;
      }
      int h = 0;
      int resourceId = mContext.getResources()
              .getIdentifier("status_bar_height", "dimen", "android");
      if (resourceId > 0) {
          h = mContext.getResources().getDimensionPixelSize(resourceId);
      }
      return h;
  }



• Underline TextView
  

  TextView textView = (TextView) view_name.findViewById(R.id.textView_name);
  textView.getPaint().setUnderlineText(true);