在Android上给ListView下方添加一个按钮

Question

我一直在尝试在Android的ListView下方添加一个按钮，但是问题是这个按钮并没有显示出来。

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout
    android:id="@+id/widget0"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <ListView
        android:id="@+id/messagelist"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_x="0px"
        android:layout_y="0px">
    </ListView>
    <Button
        android:id="@+id/addbutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_x="0px"
        android:layout_y="379px">
    </Button>
</AbsoluteLayout>

- Pallinder

---

我们不应再使用AbsoluteLayout。而是应该使用LinearLayout或RelativeLayout。 - anticafe

我使用LinearLayout，Listview的layout_height="0"和weight="1"。 - David

Answer 1

AbsoluteLayout已经过时，建议改用LinearLayout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    android:id="@+id/widget0"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <ListView
        android:id="@+id/messagelist"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_weight="1">
    </ListView>
    <Button
        android:id="@+id/addbutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button">
    </Button>
</LinearLayout>

我建议阅读有关布局的开发者文档，以获得良好的介绍。

- Cheryl Simon

---

不要使用wrap_content设置ListView的高度，改用0dip。Wrap_content很耗费资源，而且不会改变结果。 - Romain Guy

糟糕，我在我的示例中颠倒了layout_width和layout_height。已经修复了。 - Cheryl Simon

我尝试了很多方法，但找到了你的解决方案。非常感谢你。 - Tima

Answer 2

在“API Demos”示例中有这种布局的示例。 以下页面链接到示例：

http://developer.android.com/resources/samples/index.html

请查找文件LinearLayout9.java及其对应的布局文件linear_layout9.xml。为了方便起见，我已将它们粘贴在这里：

LinearLayout9.java:

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.view;

import com.example.android.apis.R;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.ArrayAdapter;

/**
 * Demonstrates how the layout_weight attribute can shrink an element too big
 * to fit on screen.
 */
public class LinearLayout9 extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.linear_layout_9);
        ListView list = (ListView) findViewById(R.id.list);
        list.setAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, AutoComplete1.COUNTRIES));
    }

}

linear_layout9.xml:

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2007 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->

<!--
    Demonstrates a simple linear layout. The layout fills the screen, with the
    children stacked from the top.
    -->

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

    <ListView android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1.0" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/linear_layout_9_button" />

</LinearLayout>

- Tyler Collier