What did you learn here?

Variables can be defined and  initialized in separate lines or in the same line

They must be defined and initialized before they can be used in your application

//import java io.*;
//javac simple.java
public class Test_this
public static void main(String args[])//this is an netry function must have
int n1 ; //just defining a variable
String str; // defining/declaring a variable
str = "my name is baba "; //initializing variable str
n1 = 25 ; //initializing a n1 variable
int l4=9;// defining and initializing variable at the same time
//variables must be initialized before you can use them
String l7="Hji";
System.out.println("hello world" + l4);
System.out.println("hello world" + l7 +str + n1);


}//main clas ends here