Android layout learning-layout_weight attribute of LinearLayout and androidlayout

Android layout learning-layout_weight attribute of LinearLayout and androidlayout

I have been confused about the layout_weight attribute. I want to learn more about the layout_weight attribute and its usage today.

•  Definition

First, let's look at what the official Android documentation says. After all, people are authoritative.

The official documents mean:

The layout_weight attribute is used to allocateExtra space (extra space ).

If the View does not want to be stretched, set layout_weight to 0. Otherwise, these pixels will be allocated proportionally

All views with these weight values greater than 0.

In other words, the android: layout_weight attribute tells LinearLayout how to arrange child components.

•  Example

To describe it with so many examples:

1. First, set a Linear_Layout layout, set the direction to horizontal, place two textviews, and do not set the Layout_weight value. We can see that

The white space is the extra space mentioned in the official document ).

Layout file code:

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     xmlns:tools="http://schemas.android.com/tools" 3     android:layout_width="match_parent" 4     android:layout_height="wrap_content" 5     android:orientation="horizontal" > 6  7     <TextView 8         android:layout_width="wrap_content" 9         android:layout_height="wrap_content"10         android:background="#f00"11         android:text="TextView1" />12     <TextView 13         android:layout_width="wrap_content"14         android:layout_height="wrap_content"15         android:background="#0f0"16         android:text="ThisIsTextView2"17         />18 </LinearLayout>

 

2. Set the value of Layout_weight for both textviews to 1.

In the preceding xml file, add the "android: layout_weight = 1" attribute to each TextView.

The layout_weight values of TextView1 and TextView2 are set to 2, 1, 1, and 2 respectively to see the running effect:

2 and 1:

1 and 2:

I believe that through the above examples and images, you should have a good understanding of the layout_weight attribute usage.

Then the problem comes again. If I want to allocate the two child components with the same width or height, how can I set layout_weight?

OnlySet the layout_width value of each sub-component to 0.In this way, the space allocation in the first step is avoided.

In this way, LinearLayout will only consider using the layout_weight value for space allocation.

1 <LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android" 2 xmlns: tools = "http://schemas.android.com/tools" 3 android: layout_width = "match_parent" 4 android: layout_height = "wrap_content" 5 android: orientation = "horizontal"> 6 7 <TextView 8 android: layout_width = "0dp" <! -- Set layout_width to 0dp to avoid space allocation in step 1 --> 9 android: layout_height = "wrap_content" 10 android: background = "# f00" 11 android: layout_weight = "1" <! -- LinearLayout allocates space based on this value --> 12 android: text = "TextView1"/> 13 <TextView 14 android: layout_width = "0dp" 15 android: layout_height = "wrap_content" 16 android: background = "#0f0" 17 android: layout_weight = "1" 18 android: text = "ThisIsTextView2" 19/> 20 </LinearLayout>

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Android: layout_weight in the LinearLayout Layout

Learn from you !~~ This test is thorough enough !~~ Hope you can find the answer !~~

Why can the android layout_weight attribute display controls in a certain proportion?

Layout_weight is the weight attribute of the component in the layout. A larger value indicates more parts of the site.