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Android runtime change switch Activity theme


static boolean mbThemeLight = false;

    public void onCreate(Bundle savedInstanceState) {
        // bla bla bla..........

private void switchTheme(){
 mbThemeLight = true;

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Další témata ....(Topics)


android.app.Application cannot be cast to android.app.Activity | android-app-application-cannot-be-cast-to-android-app-activity

If you using Context as parameter of function try this solution:

public class MyActivity extends Activity {
// bla bla bla .......
myFc( getapplicationcontext());
// OK

Chrome youtube shockwave flash plugin crashes solution | chrome-shockwave-flash-plugin-crashes

Google Chrome and Shockwave Flash crashes on youtube.com

  • open chrome://plugins/ with Google Chrome

  • click on Plus button for more details

  • find Flash (3 files)
  • disable two other Shockwave Flash

  • for more see image below



View getId is null Android | view-getid-is-null-android

If you create a button or view programmatically with OnClickListener you can set a tag key before button in parent layout is added.
And get correct button by this tag getTag() instead getId() in OnClickListener etc.

Button button = new Button(getApplicationContext());
int idOfButton = button.getId(); // return -1

String sTag = (String) button.getTag(); // return "my_button"


View overrides onTouchEvent but not performClick | view-overrides-ontouchevent-but-not-performclick

public class Panel extends SurfaceView implements SurfaceHolder.Callback {
//............... code
//............... some code
     * Process the MotionEvent.
    public boolean onTouchEvent(MotionEvent event) {
        synchronized (getHolder()) {
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
             } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
            	if(_currentGraphic==null)return true;
            } else if (event.getAction() == MotionEvent.ACTION_UP) {
            return true;
 public boolean performClick() {
  // Calls the super implementation, which generates an AccessibilityEvent
        // and calls the onClick() listener on the view, if any

        // Handle the action for the custom click here

        return true;



Android studio list of useful shortcuts or like Eclipse | android-studio-list-of-useful-shortcuts

File -> Settings -> Keymap you can do select Eclipse keymap from drop down menu

Ctrl+Shift+A (Help | Find Action on the main menu) and start typing the name of the action. Choose the desired action from the suggestion list.

Ctrl+Click (on Windows) or Cmd+Click (on MacOS) a tab in the editor to navigate to any part of the file path. Select the necessary element in the drop-down, and the corresponding file path opens in an external browser (e.g., in the Explorer, if your OS is Windows).


Find - Rename

Ctrl+F find

Refactor | Rename: Shift+F6  ( +F6)

Find and replace: CTRL + R

Go to variable declaration: CTRL + B

Ctrl+Shift+I (View | Quick Definition)

Ctrl+Alt+F7  (Edit | Find | Show Usages in the main menu)

Ctrl+Shift+F find in project

Ctrl+Shift+F7 (Edit | Find | Highlight Usages in File) to quickly highlight usages of some variable in the current file.
Use F3 and Shift+F3 keys to navigate through highlighted usages.
Press Escape to remove highlighting.

Ctrl+W (extend selection) in the editor selects the word at the caret and then selects expanding areas of the source code. For example, it may select a method name, then the expression that calls this method, then the whole statement, then the containing block, etc. You can also select the word at the caret and the expanding areas of the source code by double-clicking the target areas in the editor.

To search through the classes, files, tool windows, actions, settings, and symbols of your project by double pressing the Shift key

Ctrl+P (View | Parameter Info) e.g. localURL = new URL(localUrlString); select localUrlString and press Ctrl + P

Show html documentation tooltips:  CTRL + Q



Comment uncomment single line: CTRL + /

Comment uncomment selected text: CTRL + SHIFT + /

Code completion (Ctrl+Space)

Alt key and mouse pointer dragging for column selection

If nothing is selected in the editor, and you press Ctrl+C, then the whole line at caret is copied to the clipboard.

Ctrl + Delete  delete word from caret to end.

Ctrl + Backspace delete word from caret to start.

Duplicate line: CTRL + D

To compare two directories,or  jar files, select one or both of them in the Project view and press Ctrl+D.

Editor Delete Line: CTRL + Y

Move line UP, DOWN. Select a code fragment and press Ctrl+Shift+Up or Ctrl+Shift+Down.

To open any class or file in the editor at the desired line, press Ctrl+Shift+N (Navigate | File), start typing the name, and choose the one from the suggestion list. Then type the colon (:) and a line number

Ctrl+Shift+Enter to complete a current statement such as if, do-while, try-catch, return (or a method call)

Alt+Enter to invoke a quick fix or intention action, press the right arrow key to reveal the list of additional options.

To quickly review your recent changes to the project: Alt+Shift+C

Code Completion, you can accept the currently highlighted selection in the popup list with the period character (.), comma (,), semicolon (;), space and other characters.

Quickly move between methods in the editor:  Alt+Up and Alt+Down

Ctrl+Shift+J shortcut joins two lines into one and removes unnecessary space to match your code style

Ctrl+Shift+V to choose and insert recent clipboard contents into the text

Inheritance hierarchy for a selected class: Ctrl+H

Right-clicking on a breakpoint marker  you can quickly enable/disable the breakpoint or adjust its properties.

Evaluate the value of any expression while debugging the program, select its text in the editor (you may press a Ctrl+W a few times to efficiently perform this operation) and press Alt+F8.

Quickly evaluate the value of any expression while debugging the program, hold Alt and click this expression to see its value and calculate it, call a method, etc.

You can use the Extract Variable refactoring even on incomplete statements. Just select the necessary block in the editor and press Ctrl+Alt+V.

To open any particular method or field in editor: Ctrl+Alt+Shift+N

Add unimplemented methods: CTRL + I

Override methods: CTRL + O

Format code: CTRL + ALT + L

Show project: ALT + 1

Show logcat: ALT + 6

Hide project - logcat: SHIFT + ESC

Build: CTRL + F9

Build and Run: CTRL + F10

Alt+Shift+F10  access the Run/Debug dropdown on the main toolbar

Collapse all: CTRL + SHIFT + NumPad +

Expand all: CTRL + SHIFT + NumPad -

Editace: 2017-04-22 10:52:43
Počet článků v kategorii: 397

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