In this answer I wrote

forceLayout()

Call forceLayout() if you only want to relayout your own view's content, but don't need to trigger remeasuring of the entire view tree (all the parent views). If you had a custom ViewGroup that wasn't changing its own size but needed to remeasure and relayout its children, this would be an appropriate situation to call forceLayout().

Basically, calling requestLayout() results in a call to parent.requestLayout(), but calling forceLayout() doesn't.

As I recall I wrote my answer by reading the documentation and source code. However, I didn't experience using forceLayout. A user commented that it was not working as I described.

Testing forceLayout

I am finally getting around to researching the cause for this. I set up a simple project with a grandparent ViewGroup, a parent ViewGroup, and a child View. I used custom views for each of them so that I could watch the log statements in onMeasure, onLayout, and onDraw.

When the layout is first created from xml I get the following log:

ViewGroupGrandparent onMeasure called
ViewGroupParent onMeasure called
MyChildView onMeasure called
ViewGroupGrandparent onMeasure called
ViewGroupParent onMeasure called
MyChildView onMeasure called
ViewGroupGrandparent onLayout called
ViewGroupParent onLayout called
MyChildView onLayout called
MyChildView onDraw called

forceLayout

This looks like reasonable output. However, when I subsequently call forceLayout individually on any of the views I get nothing. If I call them all at once, then the child view's onDraw gets called.

child

childView.forceLayout();
// (no log output)

parent

viewGroupParent.forceLayout();
// (no log output)

grandparent

viewGroupGrandparent.forceLayout();
// (no log output)

all together

childView.forceLayout();
viewGroupParent.forceLayout();
viewGroupGrandparent.forceLayout();

// MyChildView onDraw called

requestLayout

On the other hand, calling requestLayout has a much bigger effect.

child

childView.requestLayout();

// ViewGroupGrandparent onMeasure called
// ViewGroupParent onMeasure called
// MyChildView onMeasure called
// ViewGroupGrandparent onLayout called
// ViewGroupParent onLayout called
// MyChildView onLayout called
// MyChildView onDraw called

parent

viewGroupParent.requestLayout();

// ViewGroupGrandparent onMeasure called
// ViewGroupParent onMeasure called
// ViewGroupGrandparent onLayout called
// ViewGroupParent onLayout called

grandparent

viewGroupGrandparent.requestLayout();

// ViewGroupGrandparent onMeasure called
// ViewGroupGrandparent onLayout called

Question

When does forceLayout have any effect? Why doesn't it seem to work as it is supposed to in my examples above?

Supplemental code

Here is the code I used to make the tests above.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.forcelayout.MainActivity">

    <com.example.forcelayout.ViewGroupGrandparent
        android:id="@+id/view_group_grandparent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <com.example.forcelayout.ViewGroupParent
            android:id="@+id/view_group_parent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">

            <com.example.forcelayout.MyChildView
                android:id="@+id/child_view"
                android:layout_width="100dp"
                android:layout_height="100dp"/>
        </com.example.forcelayout.ViewGroupParent>
    </com.example.forcelayout.ViewGroupGrandparent>

    <Button
        android:text="Click me"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="buttonClick"/>

</LinearLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void buttonClick(View view) {
        Log.i("TAG", "buttonClick: ");

        ViewGroupGrandparent viewGroupGrandparent = (ViewGroupGrandparent) findViewById(R.id.view_group_grandparent);
        ViewGroupParent viewGroupParent = (ViewGroupParent) findViewById(R.id.view_group_parent);
        MyChildView childView = (MyChildView) findViewById(R.id.child_view);


        childView.forceLayout();
        //viewGroupParent.forceLayout();
        //viewGroupGrandparent.forceLayout();

        //childView.requestLayout();
        //viewGroupParent.requestLayout();
        //viewGroupGrandparent.requestLayout();
    }
}

ViewGroupGrandparent.java

public class ViewGroupGrandparent extends LinearLayout {

    public ViewGroupGrandparent(Context context) {
        super(context);
    }

    public ViewGroupGrandparent(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ViewGroupGrandparent(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Log.i("TAG", "ViewGroupGrandparent onMeasure called");
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        Log.i("TAG", "ViewGroupGrandparent onLayout called");
        super.onLayout(changed, l, t, r, b);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Log.i("TAG", "ViewGroupGrandparent onDraw called");
        super.onDraw(canvas);
    }
}

ViewGroupParent.java

public class ViewGroupParent extends LinearLayout {

    public ViewGroupParent(Context context) {
        super(context);
    }

    public ViewGroupParent(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ViewGroupParent(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Log.i("TAG", "ViewGroupParent onMeasure called");
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        Log.i("TAG", "ViewGroupParent onLayout called");
        super.onLayout(changed, l, t, r, b);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Log.i("TAG", "ViewGroupParent onDraw called");
        super.onDraw(canvas);
    }
}

MyChildView.java

public class MyChildView extends View {

    public MyChildView(Context context) {
        super(context);
    }

    public MyChildView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public MyChildView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Log.i("TAG", "MyChildView onMeasure called");
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        Log.i("TAG", "MyChildView onLayout called");
        super.onLayout(changed, left, top, right, bottom);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Log.i("TAG", "MyChildView onDraw called");
        super.onDraw(canvas);
    }
}