toString() method in JAVA.(Different ways to use toString() method in JAVA)

CODING:

import java.text.DecimalFormat;
class tostring
{
  public static void main(String args[])
   {
    int a = 666;
    int b = -666;
    String s1 = Integer.toString(a);
    String s2 = String.valueOf(b);//also define String.valueOf(-666)
    System.out.println("String s1 = " + s1);
    System.out.println("String s2 = " + s2);
    int c = 616;
    Integer o = new Integer(c);
    String s3 = o.toString();
    System.out.println("String s3 = " + s3);
    //String s3 = new Integer(c).toString();
    //String s3 = new Integer(616).toString();
    DecimalFormat o2 = new DecimalFormat("#,###");
    String s4 = o2.format(66666);
    System.out.println("String s4 = " + s4);
    String s5 = new StringBuffer().append(6666).toString();
    System.out.println("String s5 = " + s5);
    String s6 = new StringBuilder().append(3333).toString();
    System.out.println("String s6 = " + s6);
    String binaryString = Integer.toBinaryString(333);
    System.out.println(binaryString);
    //Integer.toOctalString(),Integer.toHexString(j);
    String customString = Integer.toString(666, 7);//the base 7 number system
    System.out.println(customString);
   }
}