StackOverFlow错误-通过实例化我的对象类

Question

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;
    }
}

Answer 1

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)

Answer 2

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;
  }
}

Answer 3

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.

Answer 4

您实例化类本身。

Answer 5

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?

Answer 6

确保您的构造函数具有递归调用。

Answer 7

命令设计模式是一种处理情况的方法，其中您希望拥有执行的操作的历史记录，以便可以撤消操作等。

Answer 8

构造函数有递归调用。