[java] Eclipse won't compile/run java file

I am just trying to compile and run a simple java program. When I go to run my tester class it says select what to run and it gives me Ant Build which when highlighted says "Launches an Ant build with default settings" or Ant Build... that says "Launches an Ant build and allows it to be configured". When I try to select either of these it prompts Build failed. Reason: Unable to find ant file to run. I honestly don't know what these ant builds and files are. This is definitely a dumb question but have no idea what to do.

Your project has to have a builder set for it. If there is not one Eclipse will default to Ant. Which you can use you have to create an Ant build file, which you can Google how to do. It is rather involved though. This is not required to run locally in Eclipse though. If your class is run-able. It looks like yours is, but we can not see all of it.

If you look at your project build path do you have an output folder selected? If you check that folder have the compiled class files been put there? If not the something is not set in Eclpise for it to know to compile. You might check to see if auto build is set for your project.

• Make a project to put the files in.
  • File -> New -> Java Project
  • Make note of where that project was created (where your "workspace" is)
• Move your java files into the src folder which is immediately inside the project's folder.
  • Find the project INSIDE Eclipse's Package Explorer (Window -> Show View -> Package Explorer)
  • Double-click on the project, then double-click on the 'src' folder, and finally double-click on one of the java files inside the 'src' folder (they should look familiar!)
• Now you can run the files as expected.

Note the hollow 'J' in the image. That indicates that the file is not part of a project.

right click somewhere on the file or in project explorer and choose 'run as'->'java application'

This worked for me:

1. Create a new project
2. Create a class in it
3. Add erroneous code, let error come
4. Now go to your project
5. Go to Problems window
6. Double click on a error

It starts showing compilation errors in the code.

I was also in the same problem, check your build path in eclipse by Right Click on Project > build path > configure build path

Now check for Excluded Files, it should not have your file specified there by any means or by regex.

Cheers!