How to set both gravity and layout gravity of a LinearLayout programatically

2018-06-05 05:28:28

I am risking writing a duplicate question, but as I was researching the answer to another SO question, I realized that I couldn't find a simple question and answer that included setting both gravity and layout_gravity of a LinearLayout . Also, I was confused as to the difference between them when talking about a ViewGroup rather than just a view. I am answering my question below.

Here are some of the other questions I viewed:

How to set gravity to layout programmatically?

Set gravity for LinearLayout programmatically

android - setting LayoutParams programmatically

LayoutParams gravity not working

layout_gravity in LinearLayout

Problem with setLayoutParams method in android UI

how to set setLayoutParams for linear layout elements

Is it possible to change the layout width and height in Android at run time?

Short answer

Set gravity

linearLayout.setGravity(Gravity.CENTER);

Set layout gravity

// the LinearLayout's parent is a FrameLayout      
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(400, 400);
params.gravity = Gravity.TOP|Gravity.RIGHT;
linearLayout.setLayoutParams(params);

Background

Previously, I have explained the difference between 'gravity' and `layout_gravity' for views within a layout.

Setting the gravity of a LinearLayout itself changes the location of the views within it. Setting the layout_gravity of a LinearLayout changes how the LinearLayout is arranged within its parent layout.

This image shows a LinearLayout (brown) within a FrameLayout (white). The LinearLayout 's gravity is set to center_horizontal and its layout_gravity is set to right|bottom .

在这里输入图像描述

Here is the xml:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:id="@+id/llExample"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_gravity="right|bottom"
        android:background="#e3e2ad"
        android:gravity="center_horizontal"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/textView1"
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:background="#bcf5b1"
            android:text="TextView 1" />

        <TextView
            android:id="@+id/textView1"
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:background="#aacaff"
            android:text="TextView 2" />

    </LinearLayout>

</FrameLayout>

Changing things programmatically

The following code shows how to change both the gravity and the layout_gravity of the LinearLayout .

public class LinearLayoutGravity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.linear_layout_gravity);

        // Change the gravity (not layout_gravity) of the LinearLayout
        LinearLayout ll = (LinearLayout) findViewById(R.id.llExample);
        ll.setGravity(Gravity.CENTER);

        // Change the layout_gravity (not gravity) of the LinearLayout      
        FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(400, 400);
        params.gravity = Gravity.TOP|Gravity.RIGHT;
        ll.setLayoutParams(params);
    }
}

And here is the result:

在这里输入图像描述

How to set both gravity and layout gravity of a LinearLayout programatically

Short answer

Background

Changing things programmatically

See also