New empty android application engineering error R cannot beresolved to a variable

gen can not find the file R.java
tried the following ways
selected item , right-click to open Properties:
1. checking whether android tab check the project build target.
2. checking java build path in orler and explort check on whether the corresponding android libraries.
3. checking your Android SDK path settings : windows -> preferences: android
4. Set your Android SDK environment variables: Set ANDROID_SDK_HOME value in the path of your android sdk directory
useless


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sure you have the ADT plugin installed , this multi because of ADT Build Tools not installed cause
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I do not know what the situation is now better
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I do not know what the situation is now better