non static method cannot be referenced from a static context

Question

First some code       import java util           class TicTacToe           public static void main  String  arg           Random Random   new Random          toerunner         this leads to a path of                        methods that eventualy gets us to the rest of the code             public void CompTurn  int type  boolean debug                     boolean done   true            int a   0            while   done                          a   Random nextInt 10                if  debug    int i   0   while  i lt 20    System out print  a         i                    if  possibles a   1  done   true                       this board a    2                   to close the class    Here is the error message    TicTacToe java 85  non-static method nextInt int  cannot be referenced from a static context             a   Random nextInt 10                              What exactly went wrong  What does that error message  non static method cannot be referenced from a  static context  mean

User · Answer

Violating the Java naming conventions  variable names and method names start with lowercase  class names start with uppercase  is contributing to your confusion   The variable Random is only  in scope  inside the main method  It s not accessible to any methods called by main  When you return from main  the variable disappears  it s part of the stack frame    If you want all of the methods of your class to use the same Random instance  declare a member variable   class MyObj     private final Random random   new Random      public void compTurn         while  true          int a   random nextInt 10         if  possibles a     1           break

User · Answer

In Java  static methods belong to the class rather than the instance  This means that you cannot call other instance methods from static methods unless they are called in an instance that you have initialized in that method    Here s something you might want to do   public class Foo     public void fee              do stuff          public static void main  String  arg             Foo foo   new Foo         foo fee             Notice that you are running an instance method from an instance that you ve instantiated  You can t just call call a class instance method directly from a static method because there is no instance related to that static method

User · Answer

You re trying to invoke an instance method on the class it self    You should do       Random rand   new Random        int a   0        while   done             int a   rand nextInt 10                Instead  As I told you here stackoverflow com questions 2694470 whats-wrong

User · Answer

You are calling nextInt statically by using Random nextInt  Instead  create a variable  Random r   new Random    and then call r nextInt 10   It would be definitely worth while to check out   What is the reason behind  quot non staticmethod cannot be referenced from a static context quot    Update  You really should replace this line  Random Random   new Random      with something like this  Random r   new Random     If you use variable names as class names you ll run into a boat load of problems  Also as a Java convention  use lowercase names for variables  That might help avoid some confusion

[java] non static method cannot be referenced from a static context

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