Null Pointer Exception error

[tfitz666]

Hi, I have an assignment to make a voting program. The program compile fine, but I get the following runtime error:
Exception in thread "main" java.lang.NullPointerException
at BallotPaper.setPreference(BallotPaper.java:5)
at Test1.main(Test1.java:17)

Here's the relevant code:
Ballot Paper:

    private ArrayBasedMap<Integer, Candidate> candPreference;
    
    public void setPreference( int pref, Candidate name ){
        candPreference.put( pref, name );
    }

ArrayBasedMap is something we've been told to use. Put returns NULL if the entry is inserted correctly.
Test1:

        Candidate Homer = new Candidate( "Homer", "FF" );
        BallotPaper vote1 = new BallotPaper();
        vote1.setPreference( 1, Homer );

This might be something really simple, but I just can't figure it out.
Thanks in advance!

[JosAH]

Hi, I have an assignment to make a voting program. The program compile fine, but I get the following runtime error:
Exception in thread "main" java.lang.NullPointerException
at BallotPaper.setPreference(BallotPaper.java:5)
at Test1.main(Test1.java:17)

Here's the relevant code:
Ballot Paper:

    private ArrayBasedMap<Integer, Candidate> candPreference;
    
    public void setPreference( int pref, Candidate name ){
        candPreference.put( pref, name );
    }

Test1:

        Candidate Homer = new Candidate( "Homer", "FF" );
        BallotPaper vote1 = new BallotPaper();
        vote1.setPreference( 1, Homer );

This might be something really simple, but I just can't figure it out.
Thanks in advance!

From what I can see you never actually created a candPreference object (so the reference initialized and stays null).

kind regards,

Jos

[tfitz666]

*Face Palms* That's embarrassing:D Thanks!

[JosAH]

*Face Palms* That's embarrassing:D Thanks!

Thou art forgiven because I make the same mistake more often than not ;-)

kind regards,

Jos