CSC301: Admin: What to do you have lots of red marks in Eclipse [22/56]

Suppose you had eclipse working and then one day, eclipse looks like this:

Try

  "Project" > "Clean..." > "Clean all projects"

If that does not work, try creating a fresh eclipse-workspace.

• Exit eclipse.
• Using the finder, go to the folder that contains your eclipse-workspace.
• Rename it to oldworkspace and create a new folder called eclipse-workspace
• Inside the new eclipse-workspace, create a new folder called algs4
• Move the following folders from oldworkspace/algs4 to eclipse-workspace/algs4

  data
  lib
  src
  

• Now start eclipse in the new "eclipse-workspace". It should be as though you are starting eclipse for the first time. Follow the instructions provided earlier to add the "algs4" project and to turn off the warnings for unused variables and private fields.

The above works by copying the good files to a new eclipse-workspace. You can also try the following approach, which removes the problemantic files from the exiting eclipse-workspace instead.

• Exit eclipse

• Using the finder or terminal, remove the following files/directories:

  • eclipse-workspace/.metadata
  • eclipse-workspace/algs4/.classpath
  • eclipse-workspace/algs4/.project

  If you are using finder on a mac, you may need to make these files visible. Run Terminal and enter the following two commands:

  defaults write com.apple.finder AppleShowAllFiles 
  TRUE killall Finder
  

  To switch back, do the same but substitute FALSE for TRUE.

• Restart eclipse. You should have a blank eclipse-workspace.

• Follow the previous instructions to show the algs4 project, by following the previous instructions to install the code from class, starting with File > New > Java Project

If that does not work ensure that you have the correct version of Java installed.

• First check that Project Specific Settings are NOT checked in the following places

  Project -> Properties -> Java build path
  Project -> Properties -> Java compiler

• Then check

  Preferences -> Java -> Compiler
  Preferences -> Java -> Installed JREs

• to make sure that compliance level is set to 11 and that a Java SE 11 runtime is checked. If you don't have Java 11, then you need to install it.
• The clean all projects as described above.