R无法解决 - Android错误 [英] R cannot be resolved - Android error

问题描述

我刚刚下载并安装了新的Android SDK。

向导创建了这个代码：

  package eu.mauriziopz.gps; 
 
 import android.app.Activity; 
 import android.os.Bundle; 
 
 public class ggps extends Activity {
 / **当活动首次创建时调用。 * / 
 @Override 
 public void onCreate（Bundle savedInstanceState）{
 super.onCreate（savedInstanceState）; 
 setContentView（R.layout.main）; 
} 
} 
  

但 Eclipse 给我的错误

R无法解决

 <$> 
 $ <$ p <$> c $ c> setContentView（R.layout.main）; 
  

为什么？

在 res / layout / 下有一个名为 main.xml 的XML文件

解决方案

除了上面的答案中的建议，请确保您的Android目标已设置：

1. 选择属性


2. 在左侧菜单中选择Android

<

>编辑：一年后，我发现另一个原因。我在我的drawable文件夹中有一个.jpg图像与.png图像同名。在我的代码中引用此图像必须混淆程序，它给出了R无法解决的错误。

I just downloaded and installed the new Android SDK. I wanted to create a simple application to test drive it.

The wizard created this code:

package eu.mauriziopz.gps;

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

public class ggps extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}

but Eclipse gives me the error

R cannot be resolved

on line

setContentView(R.layout.main);

Why?

PS: I do have an XML file named main.xml under res/layout/.

解决方案

Along with the great suggestions in the previous answers, make sure your Android target is set:

1. Right-click on your project
2. Choose Properties
3. Choose Android in the left menu
4. Tick a box next to the appropriate Project Build Target.
5. Click Apply and OK

Edit: A year later I found another cause. I had a .jpg image in my drawable folder with the same name as a .png image. Referencing this image in my code must have confused the program and it gave the "R cannot be resolved" error.

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