How to make calls to methods

New here, I'm a compsci student taking a java programming class. Pretty basic suff but I'm getting caught here and there wrapping my head around some stuff.

My question right now invoves making a method that takes a single int parameter and then prints all of the positive even perfect squares less than n.
This is what I have so far:

Code :

---

public class evenSquares {
 
  public void evenSquares(int n){
    for(int j = 2; j*j <= n; j += 2)
      System.out.println(j*j);
  }
}

---

Code :

---

public class evenSquaresDriver {
  public static void main(String[] args){
 
    evenSquares testsquare = new evenSquares(1000);
  }
}

---

This is giving me an error that "The constructor evenSquares(int) is undefined"

Ok, in your evenSquares class, you have no constructor. What you do have is a method. So when you say new evenSquares(1000);, it is looking for a constructor that accepts an int.

So, there are a few ways to fix this with what you already have, depending on what you want to do:
If you want to create a constructor for your evenSquares class:

Code java:

---

public class evenSquares {
 
  public evenSquares(int n){     //NOTICE: I took out the return type to make it a constructor
    for(int j = 2; j*j <= n; j += 2)
      System.out.println(j*j);
  }
}

---

OR

If you want to have an evenSquares class, with an evenSquares method (poor programming habit, but it will work):

Code java:

---

public class evenSquaresDriver {
  public static void main(String[] args){
 
    evenSquares testsquare = new evenSquares();
    testsquare.evenSquares(1000);     //Using the empty constructor, and then calling the evenSquares(int) method
  }
}

---

You seem to not fully understand the difference between a method and a constructor. I suggest you do a little bit of reading about them to better understand how it works.

Another question with similiar idea.

The method stringRoot is passed a string of digits as a paramater and returns the square root of the number represented by those digits.

Code :

---

  public double stringRoot(String str){
    double k = Integer.parseInt(str);
    return Math.sqrt(k);
  }

---

Code :

---

stringRoot testDouble = new stringRoot();
testDouble.stringRoot("1600");

---

It's telling me "stringRoot cannot be resolved to a type"
Correct me if I'm wronge but this is a method correct? I also just threw the codes into my evenSquares and evenSquaresDriver classes

What class is the stringRoot(...) method in?

You are trying to create a new Object, of type stringRoot, and calling the new Object's stringRoot(...) method, which is clearly not what you are wanting to do.

ermmm, just do classname.stringRoot("1600")

don't think you need to make an object to use a classes method?