Pixel to density independent pixel to pixel conversion
Physical pixel (px)
Density independent pixel (dp)
Dots per inch (dpi) .. physical pixels per inch
px = dp * (dpi / 160)
Density independent pixel (dp)
Dots per inch (dpi) .. physical pixels per inch
px = dp * (dpi / 160)
public static int dpToPx(int dp)
{
return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
}
public static int pxToDp(int px)
{
return (int) (px / Resources.getSystem().getDisplayMetrics().density);
}
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Update TextView by runnable. Handler, runnable, timer Android example.
main.xml
public class TimerActivity extends Activity {
TextView hTextView;
Button hButton, hButtonStop;
private Handler mHandler = new Handler();
private int nCounter = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
hTextView = (TextView)findViewById(R.id.idTextView);
hButton = (Button)findViewById(R.id.idButton);
hButton.setOnClickListener(mButtonStartListener);
hButtonStop = (Button)findViewById(R.id.idButtonStop);
hButtonStop.setOnClickListener(mButtonStopListener);
} // end onCreate
View.OnClickListener mButtonStartListener = new OnClickListener() {
public void onClick(View v) {
try {
mHandler.removeCallbacks(hMyTimeTask);
// Parameters
// r The Runnable that will be executed.
// delayMillis The delay (in milliseconds) until the Runnable will be executed.
mHandler.postDelayed(hMyTimeTask, 1000); // delay 1 second
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
private Runnable hMyTimeTask = new Runnable() {
public void run() {
nCounter++;
hTextView.setText("Hallo from thread counter: " + nCounter);
}
};
/**
*
*/
View.OnClickListener mButtonStopListener = new OnClickListener() {
public void onClick(View v) {
mHandler.removeCallbacks(hMyTimeTask);
}
};
}
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"
>
<TextView
android:id="@+id/idTextView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button android:text="Button"
android:id="@+id/idButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></Button>
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/idButtonStop"
android:text="Stop"></Button>
</LinearLayout>
Java double is 64 bit double precision type used when fractional
precision calculation is required.
Java double je datový typ (reálné číslo) o velikosti 64 bitů. Používá se například pro přesný výsledek po dělení za desetinnou tečkou. Pokud nepotřebuje tak veliké číslo použijte raději typ float, šetříte tím paměť mobilního telefonu.
precision calculation is required.
Java double je datový typ (reálné číslo) o velikosti 64 bitů. Používá se například pro přesný výsledek po dělení za desetinnou tečkou. Pokud nepotřebuje tak veliké číslo použijte raději typ float, šetříte tím paměť mobilního telefonu.
// declaration and assignment of value type double
double x = 18.41785;
//print formated value
System.out.printf("The value of x is %.3f%n", x); // 18.418
// declaring more variables in single statement
double d1 = 12.4, d2 = 564.5, d3 = 14.589;
// double range of value
System.out.println(Double.MIN_VALUE); // 4.9E-324
System.out.println(Double.MAX_VALUE); // 1.7976931348623157E308
// is NaN Not-a-Number
double f = (double) Math.sqrt(-15);
boolean bNaN = Double.isNaN(f);
System.out.print(bNaN); // true
// check if a string is a valid number in Java example
// convert string to double Java example
String sD = "12.8";
double dParse = Double.parseDouble(sD);
// convert strings to numbers
String sDl = "15.48";
double dFromString = (Double.valueOf(sDl)).doubleValue();
// format double, float or long value to string
DecimalFormat formatter = new DecimalFormat(".##");
String s = formatter.format(-.5678); // -0.57
// .### -0.568
// .#### -0.5678
// .000000 -.567800
// -123.456
// .## -123.46
// #.## -123.46
// #E0 -.1E3
// ##E0 -1.2E2
//###E0 -123E0
// double to string in Java example code
Double dObj = new Double(68.5);
String str = dObj.toString();
// else
Double dS = 11.6;
String sdouble = dS.toString();
// compare two double variables
Double dComp1 = 4.3;
if(dComp1.equals(4.3))
System.out.print("true");
// compares the two specified double values in Java example
// int i = compare(double d1, double d2);
int i = Double.compare(11.5, 11.7); // -1 first < second
// 0 first == second
// 1 first > second
System.out.print(i);
If you do click on Rebuid project menu item, this operation maybe consume long time on slovly PC.
Some errors dismis when you do rebuild project, or module.
Try this:
Select module where contains red error code and press Debugg or Run button on Android Studio.
If module code contains errors, Android Studio show error report in gradle console.
If not, apk will installed on device.
This is 10 times faster than Clean - Rebuild all project.
Some errors dismis when you do rebuild project, or module.
Try this:
Select module where contains red error code and press Debugg or Run button on Android Studio.
If module code contains errors, Android Studio show error report in gradle console.
If not, apk will installed on device.
This is 10 times faster than Clean - Rebuild all project.
onCreate in MainActivity.java
You can add to titlebar different Views by xml file.
custom_title.xml

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
setContentView(R.layout.main.xml);
getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_title);
}
You can add to titlebar different Views by xml file.
custom_title.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="//schemas.android.com/apk/res/android" android:id="@+id/screen"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:orientation="vertical">
<TextView android:id="@+id/left_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:text="Some text" />
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:src="@drawable/ic_launcher" />
</RelativeLayout>

Editace: 2015-12-02 19:01:06
Počet článků v kategorii: 396
Url:pixel-to-density-independent-pixel-to-pixel-conversion