CODEWITHSUNDEEP
javastack-overflow
semaj
semaj

Reputation:

StackOverFlow error - from instantiating my object class

I am trying to make a class in Java that builds an object of type Action which holds three ints and returns it to my other class in the array history, where history is an array of type Action. When it is called I immediately get an endless loop; hence the stack overflow.

Error - I printed 1 line, it goes on...

Exception in thread "main" java.lang.StackOverflowError
    at sudokugame.Action.<init>(Action.java:7)

Class:

public class Action {

    Action a;
    public Action(int i, int o, int p){
      a = new Action(i,o,p);
    }

    public void   setAction(int n, int b, int c){

    }

    public Action  getAction(){
        return a;
    }
}

Upvotes: 0

Views: 530

Answers (8)

Silent Warrior
Silent Warrior

Reputation: 5265

Constructor have recursive call.

Upvotes: 0

Brian T. Grant
Brian T. Grant

Reputation: 187

The Command design pattern is one way to approach a situation where you want to have a history of actions taken so they can be undone, etc.

Upvotes: 0

nilesh
nilesh

Reputation: 2265

sure your constructor has recursive call.

Upvotes: 0

Paul Dixon
Paul Dixon

Reputation: 300825

Your constructor calls itself recursively forever. A sure way to overflow a stack :)

public Action(int i, int o, int p){
    //why do you do this?
    a = new Action(i,o,p);
}

Maybe what you really wanted to do was just store i,o and p in the class instance?

public class Action {

  int i;
  int o;
  int p;

  public Action(int i, int o, int p){
    this.i = i;
    this.o = o;
    this.p = p;
  }

  ...
}

(edit: see other answer for fuller example)

Upvotes: 12

Adrian Godong
Adrian Godong

Reputation: 8911

Try doing it this way:

public class Action {

  int i;
  int o;
  int p;

  public Action(int i, int o, int p){
    this.i = i;
    this.o = o;
    this.p = p;
  }

  public void setAction(int n, int b, int c){
    this.i = i;
    this.o = o;
    this.p = p;
  }

  public Action getAction(){
    return this;
  }
}

Upvotes: 3

Jack Leow
Jack Leow

Reputation: 22477

Does your Action class really need to hold on to a reference to another Action?

Action a;

Specifically, is this line necessary? What are you using it for?

Upvotes: 0

Andrew Hare
Andrew Hare

Reputation: 351476

The problem is here:

a = new Action(i,o,p);

You are invoking the constructor again for a new instance inside the constructor of the class itself. Since each subsequent call to the constructor will create a new constructor call there is no way for the stack to unwind, therefore creating a stack overflow.

Upvotes: 2

Jason Miesionczek
Jason Miesionczek

Reputation: 14448

Your instantiating the class within itself.

Upvotes: 0

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