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FAQ - Lab10

I’m getting the error below, what should I do?

Test Failed!
No X11 DISPLAY variable was set,
or no headful library support was found,
but this program performed an operation which requires it,

If you’re getting the error above in your testClearLines method, make sure that you’re not calling on renderBoard in the method or any method that uses the StdDraw library. The autograder does not have the capacity to render or display, so using the StdDraw library will cause an issue on the autograder.

I’m trying to play the game, but the board shows up as black a screen.

A common problem results from how runGame is structured. It might help to revisit the spec, where it goes over the details of runGame, specifically this portion:

  • If the current tetromino is unable to move down or can no longer move from its current position, it is set to null. The logic for setting it to null has been taken care of for you and you do not need to work with it.

In what instance would you want to spawn a piece?

Another issue is to ensure that you’re not clearing the board each time you render it in renderScore or any other parts of your implementation. For example, calling on StdDraw.clear in renderScore might clear the screen with a specific color each time the game tries to render the score.

My game runs and my clear lines appears to work, but it doesn’t pass the autograder test.

Instead of using the board instance variable, you’ll want to use the tiles variable/object that is passed into the clearLines method. The autograder is constructing its own kind of board and passing it in to test your clearLines method, so make sure that you’re referring to the correct variable!