从Java中的另一个类调用方法？

Question

I have two classes below and I want to call the SetPlace method in my main program.

public class Place
{
//variables
//constructors
//methods

    private String place; //only accessible within the class

    public Place()
    {
        place = null; // strings initialised as null as it doesn;t refer to anything yet -1 for int
    }

    public void SetPlace()
    {
        Place p1 = new Place();
        p1.place="Dungeon";
    }

}

public class Main {
    public static void main (String []args)
    {
          Place p1 = new Place();          
    }
}

How do I pass the SetPlace method to the Main Method and print out "Dungeon".

Any assistance is welcomed!

Answer 1

You're going to have to create an instance of that class like: Place place = new Place() and then place.SetPlace() .

Or you can make that function static so the it can be called within main without having to create a new instance of it. Note that setters probably shouldn't be static, but if you want to access a function from another class, this is how to do it.

Answer 2

You just need to write the calling statement in your main method like this:

public static void main (String []args)
{
    Place p1 = new Place();
    p1.SetPlace();// added here
}

But you may have made two mistakes: writing the SetPlace in a wrong way, and lacking of "print" statement.
a setter usually looks like this:

SetPlace(String place){
    this.place = place; // instead of creating a new instance of Place
}

and you can use System.out if you want to print something onto console:

// write this method in class Place
String getPlace(){
    return place;
}
...
// call it in Main
System.out.println(p1.getPlace());

Answer 3

It doesn't work like that. You can't pass the method as a parameter but refence to your objects/instances. In your case since you already created an instance you can just call

p1.SetPlace();

Also if you want to print it to console you should write a toString() method in your Place class then call it with a System.out call like following

public String toString()
{
  return place;
}

in main method

System.out.println(p1);

Answer 4

If you want to get the value of The String place in order to print it, you'll also need to create a getPlace() method that returns place.

And in the main method you do

p1.SetPlace();
System.out.println(p1.getPlace());

Answer 5

Create setter method for place.

Note :- as per Java guidelines ...method name must start with small character and must follow camel case.

public void setPlace(String place)
{

    this.place=place;
}

Create getter method for place and to get value call this method using reference variable of Place class.

public String getPlace()
{
  return place;
}

Now from Main class call setter method.

 Place p1 = new Place();  
 p1.setPlace("New York");