没有 XML 内容。请为您的文档添加根视图或布局

Question

我正在开发一个安卓应用程序。我是 XML 新手。我收到消息说“没有 XML 内容。请为您的文档添加根视图或布局” XML 代码如下所示。请帮忙

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

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/ref" 
        android:textSize="15dp"/>
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/ref2" 
        android:textSize="15dp"/>

    <EditText
        android:id="@+id/uname"
        android:layout_width="150dp"
        android:layout_height="25dp"
        android:inputType="text"
        android:ems="5" >

        <requestFocus />
    </EditText>

   <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/ref3" 
        android:textSize="15dp"/>

    <EditText
        android:id="@+id/pwd"
        android:layout_width="150dp"
        android:layout_height="25dp"
        android:inputType="text"
        android:ems="5" />

    <Button
        android:layout_width="60dp" 
        android:layout_height="35dp"
        android:text="@string/ref" 
        android:id="@+id/bLogin" />
  </LinearLayout>

----主要活动代码---

package com.android.disasterAlertApp;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;

public class MainActivity extends Activity {
   /** Called when the activity is first created. */
   Button login;
   @Override
   public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    login =(Button) findViewById(R.id.bLogin);
   }
}

----Manifest----
[2012-04-17 00:34:20 - Disaster Alert App] res\layout\main.xml:0: error: Resource entry      main is already defined.
[2012-04-17 00:34:20 - Disaster Alert App] res\layout\main.out.xml:0: Originally defined here.
[2012-04-17 00:34:20 - Disaster Alert App] C:\Users\Acer\workspace\Disaster Alert App\res\layout\main.out.xml:1: error: Error parsing XML: no element found
[2012-04-17 01:05:59 - Disaster Alert App] res\layout\main.xml:0: error: Resource entry main is already defined.
[2012-04-17 01:05:59 - Disaster Alert App] res\layout\main.out.xml:0: Originally defined here.
[2012-04-17 01:05:59 - Disaster Alert App] C:\Users\Acer\workspace\Disaster Alert App\res\layout\main.out.xml:1: error: Error parsing XML: no element found
[2012-04-17 01:11:14 - Disaster Alert App] res\layout\main.xml:0: error: Resource entry main is already defined.
[2012-04-17 01:11:14 - Disaster Alert App] res\layout\main.out.xml:0: Originally defined here.
[2012-04-17 01:11:14 - Disaster Alert App] C:\Users\Acer\workspace\Disaster Alert App\res\layout\main.out.xml:1: error: Error parsing XML: no element found
[2012-04-17 01:14:56 - Disaster Alert App] ------------------------------
[2012-04-17 01:14:56 - Disaster Alert App] Android Launch!
[2012-04-17 01:14:56 - Disaster Alert App] Connection with adb was interrupted.
[2012-04-17 01:14:56 - Disaster Alert App] 0 attempts have been made to reconnect.
[2012-04-17 01:14:56 - Disaster Alert App] You may want to manually restart adb from the Devices view.
[2012-04-17 01:17:27 - Disaster Alert App] Error in an XML file: aborting build.
[2012-04-17 01:37:10 - Disaster Alert App] res\layout\main.xml:0: error: Resource entry main is already defined.
[2012-04-17 01:38:42 - Disaster Alert App] res\layout\main.xml:0: error: Resource entry main is already defined.
[2012-04-17 01:38:42 - Disaster Alert App] res\layout\main.out.out.xml:0: Originally defined here.
[2012-04-17 01:38:42 - Disaster Alert App] C:\Users\Acer\workspace\Disaster Alert App\res\layout\main.out.out.xml:1: error: Error parsing XML: no element found
[2012-04-17 01:39:28 - Disaster Alert App] Error in an XML file: aborting build.

Answer 1

哦——看到“main.out.xml”了吗？当您使用 Eclipse 启动 XML 文件时会发生这种情况。只需删除'out' xml 并保留 main.xml

当您点击 Play 时，请务必选择/正在编辑一个 .java 文件，否则 eclipse 将生成一个“out.xml”并且无法启动。

Answer 2

我想指出 ADT Preview 21 中存在一个错误 - 我在此处安装了预览工具来修复 MacBook Retina 模拟器错误：Android Emulator do not scale to 100% for Mac Book Pro with Retina Display。

但是，我现在无法打开任何布局，因为它们都给了我这个错误。我发现有一种解决方法：切换到 XML 视图并进行任何编辑——即使它是一个空格。保存，再切换回图形布局，错误就消失了。

Answer 3

只需关闭 Eclipse 并重新启动。这对我有用。

Answer 4

为我工作：在 Eclipse 中单击帮助->检查更新。 如果你有可用的更新（特别是 Android 的东西）- 安装它们。