如何在屏幕底部对齐视图? [英] How do I align views at the bottom of the screen?

问题描述

这是我的布局代码；

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

    <TextView android:text="@string/welcome"
        android:id="@+id/TextView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
    </TextView>

    <LinearLayout android:id="@+id/LinearLayout"
        android:orientation="horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="bottom">

            <EditText android:id="@+id/EditText"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content">
            </EditText>

            <Button android:text="@string/label_submit_button"
                android:id="@+id/Button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content">
            </Button>

    </LinearLayout>

</LinearLayout>

这看起来像在左边，而我希望它看起来像在右边.

What this looks like is on the left and what I want it to look like is on the right.

显而易见的答案是将TextView的高度设置为fill_parent，但这不会为按钮或输入字段留出空间.

The obvious answer is to set the TextView to fill_parent on height, but this causes no room to be left for the button or entry field.

本质上，问题是我希望提交"按钮和文本条目在底部保持固定高度，而文本视图要填充其余空间.同样，在水平线性布局中，我希望提交"按钮包装其内容，并让文本输入填充其余空间.

Essentially the issue is that I want the submit button and the text entry to be a fixed height at the bottom and the text view to fill the rest of the space. Similarly, in the horizontal linear layout I want the submit button to wrap its content and for the text entry to fill the rest of the space.

如果线性布局中的第一个项目被告知fill_parent，则它确实会执行该操作，而不会为其他项目留出空间.如何获得第一个位于线性布局中的项目，以填充除布局中其余项目所需的最小空间之外的所有空间?

If the first item in a linear layout is told to fill_parent it does exactly that, leaving no room for other items. How do I get an item which is first in a linear layout to fill all space apart from the minimum required by the rest of the items in the layout?

相对布局确实是答案:

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

    <TextView
        android:text="@string/welcome"
        android:id="@+id/TextView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true">
    </TextView>

    <RelativeLayout
        android:id="@+id/InnerRelativeLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" >

        <Button
            android:text="@string/label_submit_button"
            android:id="@+id/Button"
            android:layout_alignParentRight="true"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">
        </Button>

        <EditText
            android:id="@+id/EditText"
            android:layout_width="fill_parent"
            android:layout_toLeftOf="@id/Button"
            android:layout_height="wrap_content">
        </EditText>

    </RelativeLayout>

</RelativeLayout>

推荐答案

现代的方法是使用

The modern way to do this is to have a ConstraintLayout and constrain the bottom of the view to the bottom of the ConstraintLayout with app:layout_constraintBottom_toBottomOf="parent"

下面的示例创建一个FloatingActionButton，该按钮将与屏幕的末端和底部对齐.

The example below creates a FloatingActionButton that will be aligned to the end and the bottom of the screen.

<android.support.constraint.ConstraintLayout
   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_height="match_parent"
   android:layout_width="match_parent">

<android.support.design.widget.FloatingActionButton
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"

    app:layout_constraintBottom_toBottomOf="parent"

    app:layout_constraintEnd_toEndOf="parent" />

</android.support.constraint.ConstraintLayout>

作为参考，我将保留原来的答案.

For reference, I will keep my old answer.

在引入ConstraintLayout之前，答案是相对布局.

Before the introduction of ConstraintLayout the answer was a relative layout.

如果您的相对布局可以覆盖整个屏幕，则应该可以使用

If you have a relative layout that fills the whole screen you should be able to use android:layout_alignParentBottom to move the button to the bottom of the screen.

如果底部的视图未在相对布局中显示，则其上方的布局可能会占用所有空间.在这种情况下，您可以将应位于页面底部的视图放在布局文件中的第一位，然后使用android:layout_above将其余布局放置在视图上方.这样一来，底视图就可以占用所需的空间，而布局的其余部分可以填满屏幕的所有其余部分.

If your views at the bottom are not shown in a relative layout then maybe the layout above it takes all the space. In this case you can put the view, that should be at the bottom, first in your layout file and position the rest of the layout above the views with android:layout_above. This enables the bottom view to take as much space as it needs, and the rest of the layout can fill all the rest of the screen.

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