Trouble with passing a Random object as an argument

Question

I am having trouble passing a random object as an argument.

I made a new file to test it and I got the same errors. Can anyone tell me what is wrong with this?

import java.util.*;
public class Practice {
  public static void main(String[] args) {
    Random r = new Random(1234);
    Spring (Random r);
  }

  void Spring (Random r) {
    r.nextInt(20);
  }
}

The errors I get are:

/tmp/Practice.java:5: error: ')' expected
    Spring (Random r);
                  ^
/tmp/Practice.java:5: error: illegal start of expression
    Spring (Random r);
                    ^
2 errors

Answer 1

You have a couple issues....

This is what you should be doing (see comments for explanation):

    public static void main(String[] args) {
        Random r = new Random(1234);
        //don't need Random here
        //also call static method
        Practice.Spring (r);
}
  //since you are calling a static method, you need to declare it static
  //also it's good practice to add the methods access modifier.
  private static void Spring (Random r) {
      r.nextInt(20);
}

Answer 2

To call Spring (...) you will first have to create an instance of your class. To achieve this you must call the constructor:

Practice myPractice = new Practice();

After this you can call your Spring method:

myPractice.Spring(r); //Random must be left out at this place - only when declaring the function interface