This is in Java – the thread “main” Java Exception in lang.stackoverflowerror

Why do I receive a stackoverflow error?

My class –

public class Tester {

int id;

 Tester(int id){
  this.id = id;
 }

 public String toString(){

  String rep = "Hex: " + this + ",Id: " + this.id;
  return rep;
 }

}

Main methods –

class Driver{

    public static void main(String [] args){

        Tester t = new Tester(123);
        System.out.println(t);

    }

}

Error –

Exception in thread "main" java.lang.StackOverflowError
    at java.lang.String.length(UnkNown Source)
    at java.lang.AbstractStringBuilder.append(UnkNown Source)
    at java.lang.StringBuilder.append(UnkNown Source)
    at java.lang.StringBuilder.<init>(UnkNown Source)
    at com.examscam.model.Tester.toString(Tester.java:13)
    at java.lang.String.valueOf(UnkNown Source)
    at java.lang.StringBuilder.append(UnkNown Source)

---------REPEAT !!!

Solution

You wrote:

String rep = "Hex: " + this + ",Id: " + this.id;

Simply writing in Java means that you call this indirectly toString().

I believe you are trying to override the toString () method of object, and in your toString () version, you want to print the passed ID and the hash code of the object

So replace the output

String rep = "Hex: " + this + ",Id: " + this.id;

with

String rep = "Hex: "+ this.getClass().getName().hashCode() +",Id: " + id;

You will get the output:

Hex: 1800024669,Id: 123