226faa0fe1
* commit '52f0b5740e97777658859edb8489bc3f4e6c0b16': docs: Replaced deprecated fill_parent with match_parent.
116 lines
4.4 KiB
Plaintext
116 lines
4.4 KiB
Plaintext
page.title=Linear Layout
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page.tags=linearlayout
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@jd:body
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<div id="qv-wrapper">
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<div id="qv">
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<h2>In this document</h2>
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<ol>
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<li><a href="#Weight">Layout Weight</a></li>
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<li><a href="#Example">Example</a></li>
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</ol>
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<h2>Key classes</h2>
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<ol>
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<li>{@link android.widget.LinearLayout}</li>
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<li>{@link android.widget.LinearLayout.LayoutParams}</li>
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</ol>
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</div>
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</div>
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<p>{@link android.widget.LinearLayout} is a view group that aligns all children in a single
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direction, vertically or horizontally. You can specify the layout direction with the
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<a href="{@docRoot}reference/android/widget/LinearLayout.html#attr_android:orientation">{@code
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android:orientation}</a> attribute.</p>
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<img src="{@docRoot}images/ui/linearlayout.png" alt="" />
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<p>All children of a {@link android.widget.LinearLayout} are
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stacked one after the other, so a vertical list will only have one child per
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row, no matter how wide they are, and a horizontal list will only be one row
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high (the height of the tallest child, plus padding). A {@link
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android.widget.LinearLayout LinearLayout} respects <em>margin</em>s between children
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and the <em>gravity</em> (right, center, or left alignment) of each child. </p>
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<h2 id="Weight">Layout Weight</h2>
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<div class="sidebox-wrapper">
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<div class="sidebox">
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<h3>Equally weighted children</h3>
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<p>To create a linear layout in which each child uses the same amount of
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space on the screen, set the <a
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href="{@docRoot}reference/android/view/ViewGroup.LayoutParams.html#attr_android:layout_height"
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>{@code android:layout_height}</a> of each view to {@code "0dp"} (for a
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vertical layout) or the <a
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href="{@docRoot}reference/android/view/ViewGroup.LayoutParams.html#attr_android:layout_width"
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>{@code android:layout_width}</a> of each view to {@code "0dp"} (for a
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horizontal
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layout). Then set the <a
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href="{@docRoot}reference/android/widget/LinearLayout.LayoutParams.html#attr_android:layout_weight"
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>{@code android:layout_weight}</a> of each view to {@code "1"}.</p>
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</div>
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</div>
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<p>{@link android.widget.LinearLayout} also supports assigning a
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<em>weight</em> to individual children with the <a
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href="{@docRoot}reference/android/widget/LinearLayout.LayoutParams.html#attr_android:layout_weight"
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>{@code android:layout_weight}</a> attribute.
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This attribute assigns an "importance" value to a view in
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terms of how much space is should occupy on the screen. A larger weight value allows it to expand
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to fill any remaining space in the parent view.
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Child views can specify a weight value, and then any remaining space in the view group is
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assigned to children in the proportion of their declared weight. Default
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weight is zero.</p>
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<p>For example, if there are three text fields and two of them declare a weight of 1, while the
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other is given no weight, the third text field without weight will not grow and will only occupy the
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area required by its content. The other two will expand equally to fill the space remaining after
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all three fields are measured. If the third field is then given a weight of 2 (instead of 0), then
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it is now declared more important than both the others, so it gets half the total remaining space,
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while the first two
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share the rest equally.</p>
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<h2 id="Example">Example</h2>
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<div class="figure" style="width:220px;margin-top:0">
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<img src="{@docRoot}images/ui/sample-linearlayout.png" alt="" />
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</div>
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<pre>
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<?xml version="1.0" encoding="utf-8"?>
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
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android:layout_width="match_parent"
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android:layout_height="match_parent"
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android:paddingLeft="16dp"
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android:paddingRight="16dp"
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android:orientation="vertical" >
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<EditText
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android:layout_width="match_parent"
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android:layout_height="wrap_content"
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android:hint="@string/to" />
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<EditText
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android:layout_width="match_parent"
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android:layout_height="wrap_content"
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android:hint="@string/subject" />
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<EditText
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android:layout_width="match_parent"
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android:layout_height="0dp"
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android:layout_weight="1"
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android:gravity="top"
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android:hint="@string/message" />
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<Button
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android:layout_width="100dp"
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android:layout_height="wrap_content"
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android:layout_gravity="right"
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android:text="@string/send" />
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</LinearLayout>
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</pre>
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<p>For details about the attributes available to each child view of a {@link
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android.widget.LinearLayout}, see {@link android.widget.LinearLayout.LayoutParams}.</p>
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