public abstract String toString() ;

return getClass().getName()+ "@" + Integer.toHexString(hashCode);

// Java program to demonstrate toString() Method
 
// Importing I/O classes
import java.io.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating a StringBuilder object
        // with a String pass as parameter
        StringBuilder str
            = new StringBuilder("GeeksForGeeks");
 
        // Print and display the string
        // using standard toString() method
        System.out.println("String contains = "
                           + str.toString());
    }
}

String contains = GeeksForGeeks

// Java program to demonstrate toString() Method.
 
// Importing input output classes
import java.io.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating a StringBuilder object with
        // a String pass as parameter
        StringBuilder str = new StringBuilder(
            "Geeks for Geeks contribute");
 
        // Print and display the string
        // using toString() method
        System.out.println("String contains = "
                           + str.toString());
    }
}

String contains = Geeks for Geeks contribute

// Java Program to Convert Array of Strings to A String
// Using toString() method
 
// Importing required classes
import java.io.*;
import java.util.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
 
        // Random array of string as input
        String gfg[] = { "Are", "You", "A", "Programmer" };
 
        // Creating object of StringBuilder class
        StringBuilder obj = new StringBuilder();
 
        // Adding above arrays of strings to
        // Stringbuilder object
        obj.append(gfg[0]);
        obj.append(" " + gfg[1]);
        obj.append(" " + gfg[2]);
        obj.append(" " + gfg[3]);
 
        // Note if elements are more then
        // we will be using loops to append(add)
 
        // Creating a single string
        String str = obj.toString();
 
        // Print and display the above string
        // containing all strings as a single string
        // using toString() method
        System.out.println(
            "Single string generated using toString() method is --> "
            + str);
    }
}

Single string generated using toString() method is --> Are You A Programmer