Java String

public class Main {
  public static void main(String[] args) {
    String txt = "TeXt";					                  /*	String		*/
    String txt1 = "Text2";
    int x = 10;
    int y = 20;
    int z;
    String txt2;
    System.out.println(txt);				                /*	Op Text		*/
    System.out.println(txt.length());		            /*	4			*/
    System.out.println(txt.toUpperCase());	        /*	TEXT		*/
    System.out.println(txt.toLowerCase());	        /*	text		*/
    System.out.println(txt.indexOf("X"));          	/*	2			*/
    System.out.println(txt +" "+txt1);		          /*	TeXt Text2	*//*Concatenation*/
    System.out.println(txt.concat(txt1));	          /*	TeXtText2	*//*Concatenation*/
    z=x+y;
    System.out.println(z);				                 	/*	30			*/
    txt2=txt+x;
    System.out.println(txt2);			                	/*	TeXt10		*/
    
  }
}