how to create classes in java in the same program code example

Example: using class in java

public class HelloWorld {
  public static void main(String[] args) {
   
   
   class Number{
   
   	int number;
   
   	public boolean isPos(){
   		if(number > 0){
   			return true;
   		} else {
   			return false;
   		}
   		
   	}
   }
   
   Number myNumber = new Number();
   
   myNumber.number = 7;
   
   if(myNumber.isPos()){
   	System.out.println(myNumber.number + " is positive!!!");
   } else {
   	System.out.println(myNumber.number + " is not positive!!!");
   }
   
  }
}