title: Project cannot be built until build path errors are resolved eclipse
body: <p>I am trying to build a Java project. This used to be a breeze for me but ever since I changed my workspace to another location to store my new projects, I've been running into trouble. I get these two errors.</p>
  
  <pre><code>Description Resource    Path    Location    Type
  The project cannot be built until build path errors are resolved    InterviewPractice       Unknown Java Problem
  Unbound classpath container: 'JRE System Library [JavaSE-1.7]' in project 'InterviewPractice'   InterviewPractice       Build path  Build Path Problem
  </code></pre>
  
  <p>I've looked up fixes online but none of them seem to be working for me.</p>
  
  <p>While building the project, selecting the JRE selection. I'm also not sure what to choose. I think default it was set to <code>OSGi/minimum 1.0</code> but I'm honestly not sure what that does. I simply want to build simple programs for interview practice. So <code>JavaSE-1.7</code>?</p>
  
  <p>when I click JRE system library a popup that says An error has occurred. See error log for more details. java.lang.NullPointerException</p>