Exception in thread "main" java.lang.StackOverflowError

[jose chiramal]

The below code gives me an error :

  

import java.util.*;
public class Car {
	Car()
	{
		
	}
	Car (String s)
	{
		s1=s;
	}
	Car c1 = new Car("yellow");// yellow car
	Car c2 = new Car(); // red car
	Car c3 = new Car("yellow");// yellow car
	String s1;

	
	public void test ()
	
	{
		Map mp = new HashMap();
		System.out.println("gng to print" + c1.s1);
		mp.put(c1.s1, 123);
		System.out.println("gng to print" + c2.s1);
		mp.put(c2.s1, 456);
		System.out.println("gng to print" + c3.s1);
		mp.put(c3.s1, 789);
	    
	
	}
	
	public static void main(String args [])
	
	{
		
		Car c = new Car();
		c.test();
		
	}
	
}


  

[Jesper de Jong]

Your class Car has a number of Car objects as fields:

class Car {
	Car c1 = new Car("yellow");
	Car c2 = new Car();
	Car c3 = new Car("yellow");

	// ...
}

If you create a new Car object, it is going to initialize its fields, for example c1. But c1 is also a Car object that has three Car objects as fields. And each of those again have three Car objects as fields, etcetera ad infinitum. The JVM will recursively start creating all those Car objects until the stack overflows.

[Sue Temple]

It is because you are initializing the object within itself - when you create a car, it tries to create another car, that tries to create another car and goes into a recursive loop.

Move this code to to test()

 
Car c1 = new Car("yellow");// yellow car
Car c2 = new Car(); // red car
Car c3 = new Car("yellow");// yellow car   

[Sue Temple]

Sorry about a duplicate answer, but you just beat me there, Jesper - I did not see your post when until I hit submit!

[jose chiramal]

Thanks for your replies.