LinearLayout only show first item

Question

I got problem with LinearLayout, it only shows the first child. I found a solution but i not work.
Here my xml:

Answer 1

You have defined ImageView's width as MATCH_PARENT so it will take the whole of it's parent and while the parent is HORIZONTAL then the second view will never shown. this may help you

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/qrcode_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/primary_darker"
        app:popupTheme="@style/AppTheme.PopupOverlay"/>

</android.support.design.widget.AppBarLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    android:orientation="horizontal">

    <android.support.v7.widget.AppCompatImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/qrCode_imageView"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"/>

    <android.support.v7.widget.AppCompatButton
        android:id="@+id/generate_code_button"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="@string/generate_code"
        android:layout_marginRight="@dimen/de_btn_padding"
        android:layout_marginLeft="@dimen/de_btn_padding"/>

</LinearLayout>

Answer 2

you can try this using weight attribute in image and button

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
android:orientation="horizontal">

<android.support.v7.widget.AppCompatImageView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/qrCode_imageView"
    android:layout_weight="1"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true"/>

<android.support.v7.widget.AppCompatButton
    android:id="@+id/generate_code_button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:text="@string/generate_code"
    android:layout_marginRight="@dimen/de_btn_padding"
    android:layout_marginLeft="@dimen/de_btn_padding"/>

Answer 3

I think you have to set orientation vertical to linear layout like below

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.example.hoangdang.diemdanh.QRCode.QRCodeActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/qrcode_toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@color/primary_darker"
            app:popupTheme="@style/AppTheme.PopupOverlay"/>

    </android.support.design.widget.AppBarLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:orientation="vertical">

        <android.support.v7.widget.AppCompatImageView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/qrCode_imageView"
            android:layout_centerVertical="true"
            android:layout_centerHorizontal="true"/>

        <android.support.v7.widget.AppCompatButton
            android:id="@+id/generate_code_button"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/generate_code"
            android:layout_marginRight="@dimen/de_btn_padding"
            android:layout_marginLeft="@dimen/de_btn_padding"/>

    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>