The source attachment does not contain the source for the file HashMap.class

Figure problem:

 

The first step: Windows> Preferences> Java> Installed JREs

 

 

 

 

 

 Step two: Click on the map Add> Standard VM> Directory choose their own JDK installation directory, click apply and finish

 

Step Three: Project> Build Path> Libraries> Edit to choose their own just added Standard VM (JDK)

 

 

 

 

 

 

 Renderings

 

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Origin www.cnblogs.com/feiyang930112/p/12417530.html