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Android: add snippet to action

I'm new to Android, so this may have an obvious answer, but I can't find it.

I am writing a version of a calculator application. I want to make it so that when the user clicks on one of the buttons, a fragment begins (with a large number of buttons on it, which can then be used for more input).

The code for the fragment is as follows:

import android.app.Fragment; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class VariableMenu extends Fragment { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);} public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); } public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.fragment, container, false); } }

with the XML layout as follows:

 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <Button android:id="@+id/Bx" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="X" android:onClick="onButtonClicked"/> <Button android:id="@+id/By" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toRightOf="@id/Bx" android:layout_alignTop="@id/Bx" android:text="Y" android:onClick="onButtonClicked"/> <Button android:id="@+id/Bz" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toRightOf="@id/By" android:layout_alignTop="@id/By" android:text="Z" android:onClick="onButtonClicked"/> </RelativeLayout>

(I know that I should not use hard-coded strings, but I will fix this as soon as I get back to work)

I tried adding it using fragmentation using the onTouch method of the activation button, for example:

 public void onFragmentActivated(View v) { FragmentManager fragmentManager = getFragmentManager(); FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); VariableMenu fragment = new VariableMenu(); fragmentTransaction.add(R.layout.main, fragment); fragmentTransaction.commit(); }

but it gave an error saying that "No view found for id: ... (main) for the VariableMenu fragment."

So, I did this to view in the main XML file:

 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent"> (Irrelevant things) <fragment android:id="@+id/Fragment" android:name="calculator.app.VariableMenu" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/B1"/> (Irrelevant things) </RelativeLayout>

But this led to the fragment being there as soon as the activity was created (and setContentView (R.layout.main); ran).

Is there an easy way to programmatically add and remove a fragment with a user interface for activity?

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1 answer

The problem here is that the fragment needs a container with the view identifier that is inside. Providing a layout id will result in the error you saw.

You can add a fragment to your relative layout, but for this you will need to assign the appropriate layout parameters to it so that it can be placed. It would be easier to just create a FrameLayout in a relative layout that wraps its contents and then adds a fragment there.

 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent"> <FrameLayout android:id="@+id/FragmentContainer" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/B1"/> </RelativeLayout>

Then

 fragmentTransaction.add(R.id.FragmentContainer, fragment);
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