android:layout_height 50% of the screen size

问题:

I just implemented a ListView inside a LinearLayout, but I need to define the height of the LinearLayout (it has to be 50% of the screen height).

<LinearLayout
    android:id="@+id/widget34"
    android:layout_width="300px"
    android:layout_height="235px"
    android:orientation="vertical"
    android:layout_below="@+id/tv_scanning_for"
    android:layout_centerHorizontal="true">

    <ListView
        android:id="@+id/lv_events"
        android:textSize="18sp"         
        android:cacheColorHint="#00000000"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tv_scanning_for"
        android:layout_centerHorizontal="true">
    </ListView>

</LinearLayout>

Is that possible?

I did something similar for a button and an EditText, but doesn't seem to work on Layouts.

This is my Code:

    //capture the size of the devices screen
    Display display = getWindowManager().getDefaultDisplay();
    double width = display.getWidth();

    //my EditText will be smaller than full screen (80%)        
    double doubleSize = (width/5)*4;
    int editTextSize = (int) doubleSize;

    //define the EditText 
    userName = (EditText) this.findViewById(R.id.userName);
    password = (EditText) this.findViewById(R.id.password);

    //set the size
    userName.setWidth(editTextSize);
    password.setWidth(editTextSize);

回答1:

Set its layout_height="0dp"*, add a blank View beneath it (or blank ImageView or just a FrameLayout) with a layout_height also equal to 0dp, and set both Views to have a layout_weight="1"

This will stretch each View equally as it fills the screen. Since both have the same weight, each will take 50% of the screen.

*See adamp's comment for why that works and other really helpful tidbits.

回答2:

This is easy to do in xml. Set your top container to be a LinearLayout and set the orientation attribute as you wish. Then inside of that place two linearlayouts that both have "fill parent" on width and height. Finally, set the weigth attribute of those two linearlayouts to 1.

回答3:

This is my android:layout_height=50% activity:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/alipay_login"
        style="@style/loginType"
        android:background="#27b" >
    </LinearLayout>

    <LinearLayout
        android:id="@+id/taobao_login"
        style="@style/loginType"
        android:background="#ed6d00" >
    </LinearLayout>

</LinearLayout>

style:

<style name="loginType">
    <item name="android:layout_width">match_parent</item>
    <item name="android:layout_height">match_parent</item>
    <item name="android:layout_weight">0.5</item>
    <item name="android:orientation">vertical</item>
</style>

回答4:

best way is use

layout_height="0dp" layout_weight="0.5"

for example

<WebView
    android:id="@+id/wvHelp"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="0.5" />

<TextView
    android:id="@+id/txtTEMP"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="0.5"
    android:text="TextView" />

WebView,TextView have 50% of the screen height

回答5:

You should do something like that:

<LinearLayout
    android:id="@+id/widget34"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:layout_below="@+id/tv_scanning_for"
    android:layout_centerHorizontal="true">

    <ListView
        android:id="@+id/lv_events"
        android:textSize="18sp"         
        android:cacheColorHint="#00000000"
        android:layout_height="1"
        android:layout_width="fill_parent"
        android:layout_weight="0dp"
        android:layout_below="@+id/tv_scanning_for"
        android:layout_centerHorizontal="true"
        />

</LinearLayout>

Also use dp instead px or read about it here.

回答6:

it's so easy if you want divide your screen two part vertically ( top30% + bottom70%)

<LinearLayout
            android:id="@+id/LinearLayoutTop"
            android:orientation="vertical"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="2">

     </LinearLayout>
     <LinearLayout
            android:id="@+id/LinearLayoutBottom"
            android:orientation="vertical"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1">

     </LinearLayout>

回答7:

To make sure the height of a view is 50% of the screen then we can create two sub LinearLayouts in a LinearLayout. Each of the child LinearLayout should have "android:layout_weight" of 0.5 to cover half the screen

the parent LinearLAyout should have "android:orientation" set to vertical

.

.

here is code for your reference.... this code contains two buttons of height half the screen

<LinearLayout 
android:orientation="vertical"
android:layout_height="match_parent">

<LinearLayout

    android:layout_weight="0.5"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <Button
        android:padding="10dp"
        android:layout_weight="0.5"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:text="button1"
        android:id="@+id/button1"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentBottom="true"
        />

    <Button
        android:padding="10dp"
        android:layout_weight="0.5"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:text="button2"
        android:id="@+id/button2"
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_alignParentBottom="true"
        />

    </LinearLayout>

<LinearLayout

    android:layout_weight="0.5"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">


    </LinearLayout>
   </LinearLayout>

回答8:

This kind of worked for me. Though FAB doesn't float independently, but now it isn't getting pushed down.

Observe the weights given inside the LinearLayout

<LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:id="@+id/andsanddkasd">

            <android.support.v7.widget.RecyclerView
                android:id="@+id/sharedResourcesRecyclerView"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="4"
                />

            <android.support.design.widget.FloatingActionButton
                android:id="@+id/fab"
                android:layout_width="wrap_content"
                android:layout_height="0dp"
                android:layout_gravity="bottom|right"
                android:src="@android:drawable/ic_input_add"
                android:layout_weight="1"/>

        </LinearLayout>

Hope this helps :)

回答9:

To achieve this feat, define a outer linear layout with a weightSum={amount of weight to distribute}.

it defines the maximum weight sum. If unspecified, the sum is computed by adding the layout_weight of all of the children. This can be used for instance to give a single child 50% of the total available space by giving it a layout_weight of 0.5 and setting the weightSum to 1.0.Another example would be set weightSum=2, and if the two children set layout_weight=1 then each would get 50% of the available space.

WeightSum is dependent on the amount of children in the parent layout.

回答10:

You can use android:weightSum="2" on the parent layout combined with android:layout_height="1" on the child layout.

           <LinearLayout
                android:layout_height="match_parent"
                android:layout_width="wrap_content"
                android:weightSum="2"
                >

                <ImageView
                    android:layout_height="1"
                    android:layout_width="wrap_content" />

            </LinearLayout>