Scrollable TextView doesn't allow to select text after the application is paused

Please replace below code from your XML.

<TextView
    android:id="@+id/text_view"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:enabled="true"
    android:textIsSelectable="true"
    android:focusable="true"
    android:longClickable="true" 
    android:scrollbars="vertical" />

Remove below code from program:

textView.setTextIsSelectable(true);
textView.setFocusable(true);
textView.setFocusableInTouchMode(true);

The internal code of setTextIsSelectable() method:

public void setTextIsSelectable(boolean selectable) {
        if (!selectable && mEditor == null) return; // false is default value with no edit data

        createEditorIfNeeded();
        if (mEditor.mTextIsSelectable == selectable) return;

        mEditor.mTextIsSelectable = selectable;
        setFocusableInTouchMode(selectable);
        setFocusable(FOCUSABLE_AUTO);
        setClickable(selectable);
        setLongClickable(selectable);

        // mInputType should already be EditorInfo.TYPE_NULL and mInput should be null

        setMovementMethod(selectable ? ArrowKeyMovementMethod.getInstance() : null);
        setText(mText, selectable ? BufferType.SPANNABLE : BufferType.NORMAL);

        // Called by setText above, but safer in case of future code changes
        mEditor.prepareCursorControllers();
    }

Programmatically they are also doing the same thing which I mentioned in XML. So depending on your requirements we can use it.

setting ScrollingMovementMethod gives TextView ability to scroll "by own", e.g. when you set really long text and it is cutted on bottom or edge. with ScrollingMovementMethod you can scroll TextView, there is no need to place it in scrollable container, e.g. in ScrollView or HorizontalScrollView

android:scrollbars="vertical" line says that IF this View get "scrollablility" (e.g. by above movement method) then UI should show only vertical scrollbar. from docs:

Defines which scrollbars should be displayed on scrolling or not.

and it is View docs, not TextView especially, because few extending "kinds" of Views can gain "scolllability", including all ViewGroups like ScrollView, ListView, RecyclerView etc.

and finally what this line is doing in your code? inside setTextIsSelectable you have this line:

setMovementMethod(selectable ? ArrowKeyMovementMethod.getInstance() : null);

so in fact its overwritting movement method you set few lines above in your own code. I bet that some time ago your TextView was scollable "by itself" and some day some smart guy rewritten this and put TextView in e.g. ScrollView in XML, and movement method stayed in code.

textIsSelectable is working until Activity pause, because after resuming you are (again) setting ScrollableMovementMethod, but inside setTextIsSelectable you have

 if (mEditor.mTextIsSelectable == selectable) return;

you set that mTextIsSelectable flag in first run before Activitys pause, and this flag is restored, so code below isn't fired (so movement method isn't re-set with ArrowKeyMovementMethod and your ScrollableMovementMethod stays). So answer for question what this line is doing in your code: it's breaking "selectionability" after pausing and resuming Activity, nothing besides that

note from sources of ScrollingMovementMethod and ArrowKeyMovementMethod: only in ArrowKeyMovementMethod (set as movement method inside setTextIsSelectable like above) you have overriden onTouchEvent method and inside it some lines handling selection

edit: note also that inside setTextIsSelectable you have setting "focusability", so these lines are unnecessary:

textView.setFocusable(true);
textView.setFocusableInTouchMode(true);

so you can shorten your code to just one line:

textView.setTextIsSelectable(true);

or remove all quoted Java code and add one XML line:

android:textIsSelectable="true"

I had very similar problem; texview could scroll but not selectable.

Remove this from your code:

texview.setMovementMethod(new ScrollingMovementMethod())

I add these to your textview in xml:

android:scrollHorizontally="true" android:textIsSelectable="true"