Develop Reference

Place a button in Relative layout below the custom zoomview

I want to place a Relative layout below the custom Zoomview. I don't want the content of Relative Layout to get Zoom. I want a button to be placed at center of that relative layout.
Here is my 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="wrap_content"
android:orientation="horizontal"
android:background="#drawable/images">
<com.example.acer.myapplication.ZoomView
android:id="#+id/iop"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="#string/twentyfive" />
</LinearLayout>

<?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="wrap_content"
android:orientation="vertical"
android:background="#drawable/images">
<com.example.acer.myapplication.ZoomView
android:id="#+id/iop"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:gravity="center"
android:text="#string/twentyfive" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_centerInParent="true"
android:text="Button"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</RelativeLayout>
</LinearLayout>
Never tested code, but hopefully it will work.

Try this -
<?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="wrap_content"
android:orientation="vertical"
android:background="#drawable/images">
<com.example.acer.myapplication.ZoomView
android:id="#+id/iop"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="#string/twentyfive" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="45dp"
android:layout_centerHorizontal="true"/> //Or use android:layout_centerInParent="true"
</RelativeLayout>
</LinearLayout>

Multiple Root Tags Android Studio

i'm new to xml, and i can't get past "Multiple Root Tags" error, i`ve read others questions, but nothing seems to work, how can i fix it?
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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=".MainActivity" />
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/Quantity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="8dp"
android:text="#strig/quantity"
android:textAllCaps="true"
android:textColor="#android:color/darker_gray"
android:textSize="16sp"
android:textStyle="bold" />
</LinearLayout>

Your layout should be like this:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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=".MainActivity" >
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/Quantity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="8dp"
android:text="#strig/quantity"
android:textAllCaps="true"
android:textColor="#android:color/darker_gray"
android:textSize="16sp"
android:textStyle="bold" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>

Your layout can only have one top-level tag. Yours currently has two (the ConstraintLayout and the LinearLayout). Probably you did not mean to end the ConstraintLayout tag with />; remove the slash and add a closing tag at the bottom of your file.

Bro, your syntax is incorrect
tools:context=".MainActivity" >
Try with this

android programming auto margin as in css

I am very new to android programming.I have learned css and I want to make margin 0 auto like in css.This is my code:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.qwe.androidtutorial_1.Layout">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="300dp"
android:layout_height="400dp"
android:orientation="vertical"
android:layout_marginLeft="0dp"
android:gravity="center_horizontal"
android:layout_gravity="center">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/alici"
android:visibility="visible"
android:gravity="center"
/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/konu"
android:visibility="visible"
android:gravity="center" />
</LinearLayout>
</RelativeLayout>
This is how my design looks like => IMAGE 1
I want to design like this =>IMAGE 2
I want to make this using margin 0 auto(as in css) which makes linearlayout perfectly vertically center in relativelayout.How can I make this?

set
android:gravity="center_horizontal"
in Main RelativeLayout.

You can use below code:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal">
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="300dp"
android:layout_height="400dp"
android:layout_marginTop="20dp"
android:orientation="vertical">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/alici"
android:visibility="visible"
android:gravity="center"
/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/konu"
android:visibility="visible"
android:gravity="center" />
</LinearLayout>
</RelativeLayout>
If it is useful, please vote.

listview items not filled the whole area(Expandable list view)

i am referring this to implement 3 level expandable list. the code works fine. but my problem is , the items in the child elements not filled the whole area. because of that i cant expand the next child element by clicking on it.(i have to click the exact area which is child element text appeared)
can someone point me, where is the issue?
i have edit my xml view also as android:layout_width="fill_parent"
but didn't worked..
please help me on this.
thank you.
EDIT
HERE THE ALL LAYOUT XML CODES.
ROOT
<?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="fill_parent"
android:layout_height="wrap_content"
android:background="#ff5b5b"
android:orientation="vertical" >
<TextView
android:id="#+id/itemRootTitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge"
tools:ignore="HardcodedText" />
</LinearLayout>
PARENT
<?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="fill_parent"
android:layout_height="wrap_content"
android:background="#40e0d0"
android:orientation="vertical" >
<TextView
android:id="#+id/itemParentTitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge"
tools:ignore="HardcodedText" />
</LinearLayout>
CHILD
<?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="fill_parent"
android:layout_height="wrap_content"
android:background="#839096"
android:orientation="vertical" >
<TextView
android:id="#+id/itemChildTitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge"
tools:ignore="HardcodedText" />
</LinearLayout>
MAIN XML LAYOUT
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<ExpandableListView
android:id="#+id/expList"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:choiceMode="singleChoice"
>
</ExpandableListView>
</RelativeLayout>

I also encountered this problem with a spinner
I solved it like this
child 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="fill_parent"
android:layout_height="wrap_content"
android:background="#839096"
android:orientation="vertical" >
<TextView
android:id="#+id/itemChildTitle"
android:layout_width="match_parent" <== and this
android:minWidth="500dp" <=== add this
android:layout_height="wrap_content"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge"
tools:ignore="HardcodedText" />
</LinearLayout>

Can't figure out this android error

<RelativeLayout 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"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<?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"
android:orientation="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send" />
</LinearLayout>
From this (which is from the android tutorial) I am getting an error that The processing instruction target matching "[xX][mM][lL]" is not allowed (which is on the line starting

Put <?xml version="1.0" encoding="utf-8"?> on the top of the file
Remove xmlns:android="http://schemas.android.com/apk/res/android" from LinearLayout

Put on the top below line#
<?xml version="1.0" encoding="utf-8"?>
And remove from LinearLayout below line#
xmlns:android="http://schemas.android.com/apk/res/android"
For more info refer Stackoverflow Question

I edited your layout. <?xml version="1.0" encoding="utf-8"?> this takes makes the problem:
Below layout correct:
<?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"
android:orientation="horizontal" >
<EditText
android:id="#+id/edit_message"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send" />
</LinearLayout>
</RelativeLayout>