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Java Java Objects Creating the MVP Storing Guesses

Christopher Stutler
Christopher Stutler
3,080 Points
Posted by Christopher Stutler
Christopher Stutler
3,080 Points

Error when trying to run in JShell

https://w.trhou.se/lw2x9c986a

I've gone over the code three or four times and as far as I can tell everything lines up fine. but I am getting the following error. Please helpl

game.applyGuess('t');
| java.lang.NullPointerException thrown:
| at Game.applyGuess (#1:12)
| at (#11:1)

Brendan Whiting
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points
Brendan Whiting
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

What are you typing into the console prior to that? I tried running your code and it seemed to work on my end:

jshell> Game game = new Game("treehouse");                                                                                      
game ==> Game@56ef9176                                                                                                          

jshell> game.applyGuess('t');                                                                                                   
$3 ==> true                                                                                                                     

jshell>
Christopher Stutler
Christopher Stutler
3,080 Points
Christopher Stutler
Christopher Stutler
3,080 Points

The only thing else I typed was /open Game.java

markmneimneh
markmneimneh
14,132 Points

the error is in the applyGuess method of the Game class. Post the content here so someone can help you.

Brendan Whiting
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points
Brendan Whiting
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 Points

You need to create an instance of a Game class first, which is what this line is doing:

Game game = new Game("treehouse");

Then you can try game.applyGuess('t')

2 Answers

Christopher Stutler
Christopher Stutler
3,080 Points
Christopher Stutler
Christopher Stutler
3,080 Points

Okay, It's working now. I'm not quite sure what I did differently as I spent meticulously checked everything the night I was working on it, but the code it working as shown in the example. I appreciate the help.

Christopher Stutler
Christopher Stutler
3,080 Points
Christopher Stutler
Christopher Stutler
3,080 Points

I placed the instance into the counsel before running game.applyGuess

Here is my game class

class Game {
  private String answer;
  private String hits; 
  private String misses; 

  //Forces the games to throw an answer.  Note the instance field is defined by the constructer this answer, seperating it from the arguement in the braces.

  public Game(String answer) {
    this.answer = answer; 
    hits = "";
    misses = "";
  }

  public boolean applyGuess(char letter) {
    boolean isHit = answer.indexOf(letter) != -1;
    if (isHit) {
      hits += letter;
    } else {
      misses += letter;
    }
    return isHit;

  }

}

I'm sure what I'm missing is stupid, but after cruising through the first module and a half, I seem to be stumbling here.