findViewById in onCreate returns NULL when using Fragment
Call findViewById from onCreateView
res\layout
activity_main.xml
fragment_main.xml
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.containerMoje, new PlaceholderFragment()).commit();
}
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
if (container == null) {
return null;
}
TextView mText;
mText = (TextView)rootView.findViewById(R.id.idText);
mText.setText("Hello from fragment_main");
return rootView;
}
}
}
res\layout
activity_main.xml
<FrameLayout xmlns:android="//schemas.android.com/apk/res/android"
xmlns:tools="//schemas.android.com/tools"
android:id="@+id/containerMoje"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="cz.okhelp.autoskola.MainActivity"
tools:ignore="MergeRootFrame" />
fragment_main.xml
<RelativeLayout xmlns:android="//schemas.android.com/apk/res/android"
xmlns:tools="//schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="cz.okhelp.autoskola.MainActivity$PlaceholderFragment" >
<TextView
android:id="@+id/idText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
</RelativeLayout>
396LW NO topic_id
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Další témata ....(Topics)
Tutorial by pictures how evaluate a variable in Eclipse debugger window.
1.) Open Debug perspective in Eclipse and to start debugging a Activity.
2.) Open Display window from menu Window->Show view->Display
3.) Set breakpoint where you need to evaluate a variable.
4.) Debug the Activity to breakpoint.
5.) Into the Display window type code for evaluate your variable and execute code.
6.) Check if change of value a variable
1.) Open Debug perspective in Eclipse and to start debugging a Activity.
2.) Open Display window from menu Window->Show view->Display
3.) Set breakpoint where you need to evaluate a variable.
4.) Debug the Activity to breakpoint.
5.) Into the Display window type code for evaluate your variable and execute code.
6.) Check if change of value a variable
private int[] mData = new int[2]; // fill some values into array!!
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean("myBoolean", true);
outState.putDouble("myDouble", 2.7);
outState.putInt("myInt", 5);
outState.putString("myString", "Heloo girls!");
int[] data = new int[mData.length];
for (int i = 0; i < data.length; i++) {
data[i] = mData[i];
}
outState.putIntArray("myArray", data);
}
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
boolean myBoolean = savedInstanceState.getBoolean("myBoolean", false); // false basic value
double myDouble = savedInstanceState.getDouble("myDouble", 1.5); // 1.5 basic value
int myInt = savedInstanceState.getInt("myInt", 10);
String myString = savedInstanceState.getString("myString", "Hello boys!");
int[] data = savedInstanceState.getIntArray("myArray");
if (data != null && data.length == mData.length) {
for (int i = 0; i < data.length; i++) {
mData[i] = data[i];
}
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
boolean myBoolean = savedInstanceState != null ? savedInstanceState.getBoolean("myBoolean", false) : true;
// etc. .......
}
drawOval(), setStrokeWidth(), setStyle()
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View {
// CONSTRUCTOR
public SampleView(Context context) {
super(context);
setFocusable(true);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.CYAN);
Paint p = new Paint();
// smooths
p.setAntiAlias(true);
p.setColor(Color.RED);
p.setStyle(Paint.Style.STROKE);
p.setStrokeWidth(4.5f);
// opacity
//p.setAlpha(0x80); //
canvas.drawOval(new RectF(50, 50, 20, 40), p);;
}
}
}
Bitmap size calculation:
bmpHeight * bmpWidth
For example:
Resolution of image 1024x860 = 880 640 pixels
If every pixel get 4 byte of memory:
880 640x4= 3 522 560 (3.5MB)
Get bitmap size without allocation of memory:
Get Memory size:
Make your bitmap not bigger as maxMemory size
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
bmpHeight * bmpWidth
For example:
Resolution of image 1024x860 = 880 640 pixels
If every pixel get 4 byte of memory:
880 640x4= 3 522 560 (3.5MB)
Get bitmap size without allocation of memory:
BitmapFactory.Options options = new BitmapFactory.Options();
// If set to true, the decoder will return null (no bitmap), but the out... fields will still
// be set, allowing the caller to query the bitmap without having to allocate the memory for its pixels.
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.drawable.my_image, options);
int imageHeight = options.outHeight; // 1024
int imageWidth = options.outWidth; // 860
String imageType = options.outMimeType; // .jpg .png .gif
Get Memory size:
Make your bitmap not bigger as maxMemory size
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
float density = getResources().getDisplayMetrics().density;
Debug.MemoryInfo memoryInfo = new Debug.MemoryInfo();
Debug.getMemoryInfo(memoryInfo);
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
final int freeMemory = (int) (Runtime.getRuntime().freeMemory() / 1024);
String memMessage = String.format(
"Free=%d kB,
MaxMem=%d kB,
Memory: Pss=%.2f MB, Private=%.2f MB, Shared=%.2f MB",
freeMemory,
maxMemory,
memoryInfo.getTotalPss() / 1024.0,
memoryInfo.getTotalPrivateDirty() / 1024.0,
memoryInfo.getTotalSharedDirty() / 1024.0);
((TextView)findViewById(R.id.textViewInfo)).setText(memMessage );
If the app have transparent menu and you do not want this,
try delete @style/AppTheme in application tag in AndroidManifest.xml
and try run module - project. If menu is not transparent , maybe it caused
Or try set values\styles.xml into basic Theme
try delete @style/AppTheme in application tag in AndroidManifest.xml
and try run module - project. If menu is not transparent , maybe it caused
<application
android:allowBackup="true"
android:icon="@drawable/dicts_ico"
android:label="@string/app_name"
android:theme="@style/AppTheme" // delete this row - run app - try menu
>
Or try set values\styles.xml into basic Theme
<resources>
<!--
Base application theme, dependent on API level. This theme is replaced
by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
-->
<style name="AppBaseTheme" parent="android:Theme.Black">
<!--
Theme customizations available in newer API levels can go in
res/values-vXX/styles.xml, while customizations related to
backward-compatibility can go here.
-->
</style>
<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">
<!-- All customizations that are NOT specific to a particular API-level can go here. -->
</style>
</resources>
Editace: 2014-07-12 13:48:55
Počet článků v kategorii: 396
Url:findviewbyid-in-oncreate-returns-null-when-using-fragment
