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Get Screen Size Pixels per Inch Android example


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The exact physical pixels per inch of the screen
Get size of pixel
Get DPI
Get count of pixels per inch

        float mXDpi;
        float mYDpi;
           DisplayMetrics metrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(metrics);
            mXDpi = metrics.xdpi; // The exact physical pixels per inch of the screen in the X dimension. 
            mYDpi = metrics.ydpi;
          float  mMetersToPixelsX = mXDpi / 0.0254f; // 1 inch == 0.0254 metre
          float  mMetersToPixelsY = mYDpi / 0.0254f;



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364

Center View in RelativeLayout Android | center-view-in-relativelayout-android


RelativeLayout like parent, child Srollview is centered horizontal.
Second RelativeLayout in SrollView have gravity center, every child will centered horizontally and vertically.


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:gravity="center_horizontal">

    <ScrollView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/scrollView2" >

        <RelativeLayout
            android:layout_width="320dp"
            android:layout_height="wrap_content"
            android:background="#e6f825"
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            <Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
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                android:id="@+id/button" />
        </RelativeLayout>
    </ScrollView>

</RelativeLayout>
72

While cycle loop in Java example | while-cycle-loop-in-java-example


While cycle Java basic example with array of strings.

MainClass.java

public class MainClass {
	public static void main(String[] arg) {
		String[] arrayOfString = { "Hello", "people", "hello", "world!" };
                int i = 0;
		while ( i < arrayOfString.length ){
			System.out.println(arrayOfString[i]);
			i++;
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354

Start Activity from list - launches other activities from list | start-activity-from-list-launches-other-activities-from-list


Activities launcher

public class MainActivity extends ListActivity {
    private class Sample {
        private CharSequence title;
        private Class<? extends Activity> activityClass;

        public Sample(int titleResId, Class<? extends Activity> activityClass) {
            this.activityClass = activityClass;
            this.title = getResources().getString(titleResId);
        }

        @Override
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        }
    }

    private static Sample[] mSamples;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Instantiate the list of samples.
        mSamples = new Sample[]{
                new Sample(R.string.title_first_app, FirstActivity.class),
                new Sample(R.string.title_second_app, SecondActivity.class),
                new Sample(R.string.title_third_app, ThirdActivity.class),
        };

        setListAdapter(new ArrayAdapter<Sample>(this,
                android.R.layout.simple_list_item_1,
                android.R.id.text1,
                mSamples));
    }

    @Override
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        // Launch the sample associated with this list position.
        startActivity(new Intent(MainActivity.this, mSamples[position].activityClass));
    }
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296

On orientation changed view button textview not visible Android | on-orientation-changed-view-button-textview-not-visible-android


Try add to AndroidManifest.xml configChanges for your Activity
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 <activity android:name=".MainActivity"
                  android:label="@string/app_name"
                  android:configChanges="keyboardHidden|orientation|screenSize"
                  >
116

AlertDialog - MessageBox - Alert - Toast - Android sample | alertdialog-like-messagebox-android-sample


AlertDialog like MessageBox by WinApi:
If error: Unable to add window -- token null is not for an application
try change get Context.

// you can put this text into some function body or case in switch statement
                new AlertDialog.Builder(this)
                    .setMessage("Hello boys!!!")
                    .setPositiveButton("OK", null)
                    .show();



Context context = getApplicationContext();
	AlertDialog.Builder builder = new AlertDialog.Builder(context);
	builder.setTitle("Select font size");
	final CharSequence[] chsSize= { "Small", "Medium", "Large"};
	builder.setSingleChoiceItems(chsSize, 0 /*sel.item*/, 
	new DialogInterface.OnClickListener() {
 	    public void onClick(DialogInterface dialog, int item) {
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	        dialog.dismiss();
	    }
	});
	AlertDialog alert = builder.create();
	alert.show();
    


Editace: 2013-12-09 13:06:15
Počet článků v kategorii: 397
Url:get-screen-pixels-android-example

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