What happens when we print object in java in depth ?

What happens when we print object in java in depth ?

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sandeep negi
·

2 min read

Motivation

understanding deeply what happens when we print object in java.

Background

we have a list of employee object and we are trying to print that

Example

empList.stream().forEach(e -> System.out.println(e));

here we are printing the object so what is the output here.

practiceJava.Employee@87aac27
practiceJava.Employee@3e3abc88

Explaination

out put here is the class name at and then location where object is stored in the memory.

when we print any object in java first it will look for toString method in the same class if the method is there that will be used , if method is not there it will go to parent or super class if method is there that will be used, and if no method is there, it will go to the parent class that is object class where toString method is defined which will print classname and location of object stored in memory

Further

  1. Definition of toString in Object Class
  2. Define toString in Employee Class and then print object
  3. Define toString only in the parent object class and then check output

Definition of toString in Object Class

public String toString() {
      return getClass().getName()+"@"+Integer.toHexString(hashCode());
}

Define toString in Employee Class and then print object

    public String toString() {
        return this.name;
    }

Output

sandy
amit

Define toString only in the parent object class and then check output

  • in that case parent definition is used, if defined in both child and parent in that case child definition is being used.
Java