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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Example source code for Android Developers
// clickable TextView
public TextView createTextView(String sText, Context con){
TextView b = null;
try {
b = new TextView (con);
b.setTextSize(15.0f);
b.setTextColor(Color.rgb( 0, 0, 200));
b.setOnClickListener(this);
b.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
b.setText(sText);
//tr.addView(b, 60,30);
} catch (Exception e) {
e.printStackTrace();
return b;
}
return b;
}
/*****************/
public void onClick(View view) {
try {
String s = ((TextView) view).getText().toString();
}
catch (Exception e1) {
e1.printStackTrace();
}
}
/***********/
// if you want restore in TextView after chagne of orientation
// you have to put code to Manifest.xml android:configChanges
activity android:name=".main"
android:label="@string/app_name"
android:configChanges="keyboardHidden|orientation" //this line important !!!!!!!
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
public String toString() {
return title.toString();
}
}
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
protected void onListItemClick(ListView listView, View view, int position, long id) {
// Launch the sample associated with this list position.
startActivity(new Intent(MainActivity.this, mSamples[position].activityClass));
}
}
Create file restartADB.bat in folder
c:\Program Files\Android\android-sdk-windows\platform-tools\
Write into restartADB.bat this code:
Save restartADB.bat file.
If you want restart adb.exe server, run restartADB.bat by double click on icon.
Next example:
[caption id="attachment_778" align="alignleft" width="300" caption="ADB server restart by command line"][/caption]
Try restart ADB if this or similar errors:
Emulator] emulator: emulator window was out of view and was recentred
c:\Program Files\Android\android-sdk-windows\platform-tools\
Write into restartADB.bat this code:
adb kill-server && adb start-server
pause
Save restartADB.bat file.
If you want restart adb.exe server, run restartADB.bat by double click on icon.
Next example:
- Open Total Commander
- Open folder with adb.exe usually in
c:\Program Files\Android\android-sdk-windows\platform-tools\ - Put into command line command: adb kill-server && adb start-server and press Enter
[caption id="attachment_778" align="alignleft" width="300" caption="ADB server restart by command line"][/caption]
Try restart ADB if this or similar errors:
Emulator] emulator: emulator window was out of view and was recentred
Set in AndroidManifest.xml android:theme="@android:style/Theme.NoTitleBar" AndroidManifest.xml example source code.
AndroidManifest.xml
AndroidManifest.xml
<manifest xmlns:android="//schemas.android.com/apk/res/android"
package="com.myexample.without_titlebar">
<application android:label="My app">
<activity android:name="NoTitleBar"
android:theme="@android:style/Theme.NoTitleBar"
android:screenOrientation="portrait"
android:configChanges="keyboardHidden|orientation">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Google Android button example source code for developers.
// get handle
Button myButton;
myButton = (Button)findViewById(R.id.idMyButton);
//set focus
myButton.requestFocus();
// set background image
myButton.setBackgroundResource(R.drawable.backImage);
// or
myButton.setBackgroundDrawable(getResources().getDrawable( R.drawable.someImage));
// set visibility
myButton.setVisibility(View.INVISIBLE); // VISIBLE
///////// SET LISTENER
Button myButton =(Button)findViewById(R.id.button1);
myButton.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "AHOJ",
Toast.LENGTH_LONG).show();
}
});
// or set onClickListener
myButton.setOnClickListener(myListener);
//end onCreate .....
private OnClickListener myListener = new OnClickListener() {
public void onClick(View v) {
}
}
Editace: 2011-09-26 20:49:50
Počet článků v kategorii: 396
Url:float-in-java-example-code