float in Java example code
Android development
Java float is 32 bit single precision type and used when fractional precision calculation is required.
Java float je 32 bitů veliké číslo sloužící především pro přesný výsledek za desetinnou tečkou například při dělení čísel. Pro větší přesnost použíijte 64 bitový typ Double.
Java float is 32 bit single precision type and used when fractional precision calculation is required.
Java float je 32 bitů veliké číslo sloužící především pro přesný výsledek za desetinnou tečkou například při dělení čísel. Pro větší přesnost použíijte 64 bitový typ Double.
// declaration and assignment of value type float
float x = 18.41785f;
//print formated value
System.out.printf("The value of x is %.3f%n", x); // 18.418
// declaring more variables in single statement
float f1 = 12.4F, f2 = 564.5F, f3 = 14.589F;
// float range of value
System.out.println(Float.MIN_VALUE); // 4E-45
System.out.println(Float.MAX_VALUE); // 4028235E38
// is NaN Not-a-Number
float f = (float) Math.sqrt(-15);
boolean bNaN = Float.isNaN(f);
System.out.print(bNaN); // true
// check if a string is a valid number in Java example
// convert string to float Java example
String sF = "12.8";
float fParse = Float.parseFloat(sF);
// convert strings to numbers
String sFl = "15.48";
float fFromString = (Float.valueOf(sFl)).floatValue();
// float to string in Java example code
Float fObj = new Float(68.5);
String str = fObj.toString();
// else
Float fS = 11.6f;
String sFloat = fS.toString();
// compare two float variables
Float fComp1 = 4.3f;
if(fComp1.equals(4.3f))
System.out.print("true");
// compares the two specified float values in Java example
int i = Float.compare(11.5f, 11.7f); // -1 first < second
// 0 first == second
// 1 first > second
System.out.print(i);
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Další témata ....(Topics)
R.string.app_name to String example.
MyActivity.java
res/values/string.xml
MyActivity.java
Resources res = getResources();
String sText = res.getString(R.string.app_name);
res/values/string.xml
<resources>
<string name="app_name">My app name</string>
</resources>
entry put iterate Map HashMap Java Android
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("key27", 27);
for (Map.Entry<String, Integer> entry : map.entrySet())
{
String str = entry.getKey();
int n = entry.getValue();
}
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>
I tried this Eclipse and work fine:
Eclipse Classic
//www.filehippo.com/download_eclipse_classic_32/
Eclipse Juno
Eclipse Helios
//developer.android.com/tools/sdk/eclipse-adt.html
Eclipse Classic
//www.filehippo.com/download_eclipse_classic_32/
Eclipse Juno
Eclipse Helios
//developer.android.com/tools/sdk/eclipse-adt.html
static boolean mbThemeLight = false;
@Override
public void onCreate(Bundle savedInstanceState) {
if(mbThemeLight)
setTheme(android.R.style.Theme_Light);
super.onCreate(savedInstanceState);
// bla bla bla..........
}
private void switchTheme(){
mbThemeLight = true;
this.recreate();
}
Editace: 2011-09-26 20:49:50
Počet článků v kategorii: 396
Url:float-in-java-example-code