In android studio why layout width matchparent changes to 368dp automatically?

Question

I am doing a project using android studio. In android studio when I fix layout width as matchparentit automatically changes to 368dp. I need layoutwidth as matchparent but changes by default.

why?

kindly help me to fix this problem.

Answer 1

I had the the same issue and i was using ConstraintLayout. All i had to do to for android studio to stop rewriting my width was to ensure the app:layout_constraintRight_toRightOf="parent" is set to something in my case here i set it to parent

<android.support.constraint.ConstraintLayout
    android:id="@+id/activity_content"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <!--header row-->
    <include
        android:id="@+id/content_header"
        layout="@layout/adapter_fish_row_header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginLeft="4dp"
        android:layout_marginTop="8dp"
        android:layout_marginStart="4dp"
        android:layout_marginRight="4dp"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintHorizontal_bias="0.0" />

    <!-- The main content view -->
    <android.support.v7.widget.RecyclerView
        android:id="@+id/fish_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scrollbars="vertical"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/content_header"
        android:layout_marginLeft="4dp"
        android:layout_marginTop="8dp"
        android:layout_marginStart="4dp"
        android:layout_marginRight="4dp"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintHorizontal_bias="0.0" />

    <Button
        android:id="@+id/form_submit_button"
        style="@style/form_submit_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="4dp"
        android:layout_marginLeft="4dp"
        android:layout_marginRight="4dp"
        android:layout_marginStart="4dp"
        android:background="@color/primary"
        android:text="@string/btn_next_page"
        android:textColor="@color/text_primary"
        app:layout_constraintHorizontal_bias="0.496"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_marginTop="8dp"
        app:layout_constraintTop_toBottomOf="@+id/fish_list" />


</android.support.constraint.ConstraintLayout>

Answer 2

Replace "match_parent" with "0dp" and add constraints to ConstraintLayout.

For example, a Button attached to bottom, height 50px and width that matches parent:

<Button
    android:layout_width="0dp"
    android:layout_height="50dp"
    android:background="@color/azzurro"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintBottom_toBottomOf="parent"
    android:text="MY BUTTON"
/>

Answer 3

Probably because one of your parents is a ConstraintLayout.

https://developer.android.com/training/constraint-layout/index.html

If you don't want to deal with constraints just replace your ConstraintLayout with a FrameLayout or similar.