Android - activity_main无法解析或不是字段

Question

以前的人有相同的错误消息,但解决方案一直是删除或修改一些导入"android.R".我没有这么重要,所以我真的迷失了

我正在尝试运行示例Android谷歌地图程序.

我正在学习本教程.http://www.vogella.com/articles/AndroidGoogleMaps/article.html

但是,当我粘贴代码时,eclipse会给我这个错误:"activity_main无法解析或者不是字段"

这段代码中的MainActivity会发生这种情况

  public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;}

具体错误发生在"R.menu.activity_main"部分.

这是我的activity_main.xml文件.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

<fragment
    android:id="@+id/map"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    class="com.google.android.gms.maps.MapFragment" />
</RelativeLayout> 

这是我的完整MainActivity.java类

package com.example.mapssample;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends Activity {
  static final LatLng HAMBURG = new LatLng(53.558, 9.927);
  static final LatLng KIEL = new LatLng(53.551, 9.993);
  private GoogleMap map;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
        .getMap();
    Marker hamburg = map.addMarker(new MarkerOptions().position(HAMBURG)
    .title("Hamburg"));
Marker kiel = map.addMarker(new MarkerOptions()
    .position(KIEL)
    .title("Kiel")
    .snippet("Kiel is cool")
    .icon(BitmapDescriptorFactory
        .fromResource(R.drawable.ic_launcher)));

// Move the camera instantly to hamburg with a zoom of 15.
map.moveCamera(CameraUpdateFactory.newLatLngZoom(HAMBURG, 15));

    // Zoom in, animating the camera.
    map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
  }

} 

提前感谢您的帮助.很抱歉我的代码中有一些不确定的缩进,我不断给出四个额外的空格,使它看起来像代码,它有点奇怪.

新的错误日志.

非常感谢你,你知道这意味着什么吗？

06-07 22:45:25.226: E/AndroidRuntime(29901): FATAL EXCEPTION: main
06-07 22:45:25.226: E/AndroidRuntime(29901): java.lang.NoClassDefFoundError: com.google.android.gms.R$styleable
06-07 22:45:25.226: E/AndroidRuntime(29901):    at com.google.android.gms.maps.GoogleMapOptions.createFromAttributes(Unknown Source)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at com.google.android.gms.maps.MapFragment.onInflate(Unknown Source)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.Activity.onCreateView(Activity.java:4713)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:260)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.Activity.setContentView(Activity.java:1893)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at com.example.mapssample.MainActivity.onCreate(MainActivity.java:23)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.Activity.performCreate(Activity.java:5058)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2174)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.ActivityThread.access$700(ActivityThread.java:141)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1267)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.os.Looper.loop(Looper.java:137)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at android.app.ActivityThread.main(ActivityThread.java:5059)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at java.lang.reflect.Method.invokeNative(Native Method)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at java.lang.reflect.Method.invoke(Method.java:511)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:555)
06-07 22:45:25.226: E/AndroidRuntime(29901):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

你的代码导入android.R所以首先删除此行导入android.R;

所以删除这一行并按cntrl + shift + o(导入必要的包)..

Answer 2

1)您的布局文件存在于何处？它是在布局文件夹下然后不应该

R.layout.activity_main

2)您仍然需要导入项目R文件

com.example.mapssample.R;

3)如果代码中没有错误,则自动生成R文件.有时当你得到无法解决R文件错误意味着你在项目的其他地方有问题.尝试清洁项目.它可能有所帮助.

4)你真的不需要菜单来测试这个项目.您显示的activity_main文件也已包含在项目中,并且位于布局文件夹中.只需评论菜单部分即可.

Answer 3

我在我的应用程序中遇到了同样的错误,我通过1.removing import android.R;和import com.example.yourpakagename.R;2.3 解决了它.之后清理项目.运行项目