Android Import project, R resource file cannot be generated

When you use open source code in Android or develop your own projects, you often encounter the R.java file loss situation, how to regenerate it?
There are two ways to do this online:

Method 1: Right-click your project (project)-->android Tools-->fix project Properties.
Method 2: Right-click your project (project)-->properties-->android--> Select the appropriate target and click Apply.
However, when I debug an open source project today, I find neither of these methods is going to work. It was later discovered that if an error occurs in the resource file, the R.java file cannot be regenerated. In this case you must modify the error in the resource file according to the error prompt given by the console. These errors may be due to the duplicate name of your picture, or to an error in the layout file, or string.xml file error.

But mine is the build environment version is too low, it turns out 2.3 to 4.2 and then clean.