Java：使用 Static 方法在 Main 之外的方法中调用 Object

Question

Should be an easy fix but I was wondering how to use an object that is created in main. I tried to say Human h; outside of main (or any other methods) so I could call it in other methods but because I am using static methods I can't use h. Right now with this code, java tells me that h cannot be found (in the human roll method.)

import java.util.Scanner;

class Main
 {
  // static Human h;
  public static void main(String[] args) 
  {
    Scanner scan = new Scanner(System.in);
    Computer c = new Computer();
    Human h = new Human();
    System.out.println("Let's play PIG");
    System.out.println("What is your name");
    String name = scan.nextLine();
    System.out.println("Hello" + " " + name + " " + "you can go first");
    startGame(h, name); 
}
public static void startGame(Human h, String name)
{
Scanner scan = new Scanner(System.in); 
System.out.println("Press r to start your roll");
String rresponse = scan.nextLine();
if(!rresponse.equalsIgnoreCase("R"))
{
System.out.println("Try again");
startGame(h, name);
}
if(rresponse.equalsIgnoreCase("R"))
{
System.out.println("You pressed r, lets roll");
humanRoll(h, name);
}
}
public static void humanRoll(Human h, String name)
{
if(h.getRollNumh()==1)
{
System.out.println(name + " " + "you got a " + h.getRollNumh());
System.out.println("You got a score of" + h.getHumanTurnScore() + "this turn");
System.out.println("Here is your current overall score" + h.getHumanOverallScore());
System.out.println("Your rolled a one, now its the Computers' turn");
switchHuman();
}
}
 }

If you need to see the Human class to provide context I can quickly respond and add it in but it's just instance variables, default constructors, overloaded constructors, accessor methods, and mutator methods.

Answer 1

You can pass Human as method parameter to startGame and humanRoll defined them as

public static void startGame(Human human) 
public static void humanRoll(Human human)

Then, in main, invoke startGame(h) .

see if this works...

import java.util.Scanner;

class Main {

//tried to put Human h; up here but didn't work due to static methods 

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    Computer c = new Computer();
    Human h = new Human();
    System.out.println("Let's play PIG");
    System.out.println("What is your name");
    String name = scan.nextLine();
    System.out.println("Hello" + " " + name + " " + "you can go first");
    startGame(h);
  }

  public static void startGame(Human h) {
    Scanner scan = new Scanner(System.in);
    System.out.println("Press r to start your roll");
    String rresponse = scan.nextLine();
    if (!rresponse.equalsIgnoreCase("R")) 
    {
      System.out.println("Try again");
      startGame(h);
    }
    if (rresponse.equalsIgnoreCase("R")) 
    {
      System.out.println("You pressed r, lets roll");
      humanRoll(h);
    }
  }

  public static void humanRoll(Human h) 
  {
//RollNumh is just the dice number that the player rolled 
    if (h.getRollNumh() == 1) 
    {
      System.out.println(name + " " + "you got a " + h.getRollNumh);
      System.out.println("You got a score of" + h.getHumanTurnScore() + "this turn");
      System.out.println("Here is your current overall score" + h.getOverallHumanOverallScore());
      System.out.println("Your rolled a one, now its the Computers' turn");
      switchHuman();
    }
  }

}

Answer 2

If you want the Human h to be static (only one in your program), then you can define it as such:

static Human h;

public static void main(...) {
...

Answer 3

In Java, Variables declared inside a function can only be used inside the function. We say the scope of the variable is only within the function.

Fix: you can pass your variable h as an argument to your other functions.