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Android Studio reduce memory usage of PC


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File->Settings->Plugins and disable some plugins:

  • Google Cloud Testing

  • Google Cloud Tools Core

  • Google Cloud Tools for Android Studio

  • CVS Integration

  • Git Integration

  • GitHub

  • hg4idea

  • Subversion Integration


Use Emulator AVD with small memmory usage. For example: Virtual tablet with hight resolution have big memmory usage. Virtual phone with 240x320 resolution have small memmory usage.

Use instaed of Emulator, real device connected by USB (smarphone Samsung Galaxy or other recommended by Google whit debugable mode).

If you notice that Android Studio works slowly, consider the possibility to reduce the number of folders under antivirus protection.
Each antivirus check in your project consumes resources. You can significantly improve the performance, if you exclude certain folders from the antivirus protection.

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367

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

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

57

Change TableRow background color if on row click Android example | change-tablerow-background-color-if-on-row-click-android-example


Change table row background color if user click on row Android example code.
MainActivity.java

public class MainActivity extends Activity {
Boolean bColorYellow = true;
TextView hTextView;
TableRow hTableRow;
@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        hTextView = (TextView)findViewById(R.id.idTextView);
        hTableRow = (TableRow)findViewById(R.id.idTableRow1);


        
        
    } // end onCreate
  
    
    public void myTableRowClickHandler(View view) {
		switch (view.getId()) {
		case R.id.idTableRow1:{
			
			if(bColorYellow){
			hTableRow.setBackgroundColor(Color.GREEN);
			bColorYellow = false;
			}
			else{
			hTableRow.setBackgroundColor(Color.YELLOW);
			bColorYellow = true;
			}
		}
		break;
		}
  }
}


main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >


<TableLayout android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/tableLayout1">
    <TableRow android:id="@+id/idTableRow1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:background="#5655AA"
    android:onClick="@string/myTableRowClick"
    android:focusable="true">
<TextView  
	android:id="@+id/idTextView"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
    
    </TableRow>
</TableLayout>
    
    
</LinearLayout>



strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World!</string>
    <string name="app_name">TableRow</string>
    <string name="myTableRowClick">myTableRowClickHandler</string>
</resources>






121

Android button text alignment left right - sample | android-button-textalignment


android:gravity="left|center_vertical" or android:gravity="right|center_vertical"
               
<Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="left|center_vertical"
                    android:paddingLeft="20dp"
                    android:text="My Button"
                     />

8

Display screen size resolution density dimension Android | display-screen-dimension


Get display, screen resolution - dimension Android phone development example source code.

 Display display = getWindowManager().getDefaultDisplay();
int nWidth = display.getWidth();
int nHeight = display.getHeight();

          DisplayMetrics metrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(metrics);
            //get density per inch for example: 120 , 160 , 240
            mXDpi = metrics.xdpi; // 160 The exact physical pixels per inch of the screen in the X dimension. 
            mYDpi = metrics.ydpi;

// density
int nDensity = metrics.densityDpi; // 160 screen density expressed as dots-per-inch

          float  mMetersToPixelsX = mXDpi / 0.0254f; // 1 inch == 0.0254 metre
          float  mMetersToPixelsY = mYDpi / 0.0254f;
          
// Resolution
// The total number of physical pixels on a screen.
int wPix = metrics.widthPixels; // 320 The absolute width of the display in pixels.
int hPix = metrics.heightPixels; // 480 The absolute height of the display in pixels.
int nWidthDisplay = (wPix < hPix)? wPix : hPix;

float nWidthScreenInInch = wPix / mXDpi; //320 / 160 == 2.0 in inch.
float nHeightScreenInInch = hPix / mYDpi; //480 / 160 == 3.0 in inch.

// for example:
// density 120 per inch
//width 320 pix / 120 dpi == width 2.66 inch
//height 480 pix / 120 dpi == height 4.0 inch 

// density 240 per inch
//width 320 pix / 240 dpi == width 1.33 inch
//height 480 pix / 240 dpi == height 2.0 inch 




Example:
HTC Desire HD
11 (4.3) Diagonal cm (in)
480×800 Resolution
85 (217) ppcm (PPI - Pixels per inch)

480 / 217 = 2.21 inch
800 / 217 = 3.69 inch
Math.sqrt( 2.21*2.21 + 3.69 * 3.69) = 4.3 inch - diagonal

//en.wikipedia.org/wiki/Pixels_per_inch
//en.wikipedia.org/wiki/Dots_per_inch

Typical screen widths:

320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).


Emulator skins in the Android SDK
//developer.android.com/guide/practices/screens_support.html









































Low density (120), ldpi

Medium density (160), mdpi

High density (240), hdpi

Extra high density (320), xhdpi

Small screen
QVGA (240x320) 480x640

Normal screen
WQVGA400 (240x400)

WQVGA432 (240x432)
HVGA (320x480) WVGA800 (480x800)

WVGA854 (480x854)

600x1024
640x960

Large screen
WVGA800** (480x800)

WVGA854** (480x854)
WVGA800* (480x800)

WVGA854* (480x854)

600x1024

Extra Large screen
1024x600 WXGA (1280x800)

1024x768
1280x768
1536x1152
1920x1152

1920x1200
2048x1536
2560x1536

2560x1600
* To emulate this configuration, specify a
custom density of 160 when creating an AVD that uses a WVGA800 or WVGA854 skin.

** To emulate this configuration, specify a custom density of 120 when creating an AVD that
uses a WVGA800 or WVGA854 skin.

† This skin is available with the Android 3.0 platform
159

Array copy to Array Java Android example | array-copy-to-array-java-android-example



    String[] source = {"Hello","world","by","Android"};
    
    String[] destination = new String[source.length];
   
    System.arraycopy(source, 0, destination, 0, source.length);



Editace: 2015-10-31 10:11:29
Počet článků v kategorii: 397
Url:android-studio-reduce-memory-usage

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