Добавление кнопки под списком на Android

Question

Итак, я пытался добавить кнопку под списком в Android, проблема в том, что кнопка не появляется.

<?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>

Answer 1

AbsoluteLayout устарела. Вместо этого я бы предложил использовать 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>

Я бы также предложил прочитать документацию для разработчиков в макетах для хорошего ознакомления.

Answer 2

Пример такого макета приведен в примере «Демоверсии API». Следующая страница ссылается на образцы:

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

Найдите файл LinearLayout9.java и соответствующий файл макета linear_layout9.xml. Для удобства я их вставил сюда:

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>