Calling Non-Static Method In Static Method In Java

Question

I m getting an error when I try to call a non-static method in a static class      Cannot make a static reference to the non-static method methodName   from the type playback   I can t make the method static as this gives me an error too      This static method cannot hide the instance method from xInterface   Is there any way to get round calling an non-static method in another static method   The two methods are in seperate packages and seperate classes

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You could create an instance of the class you want to call the method on  e g    new Foo   nonStaticMethod

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You need an instance of the class containing the non static method    Is like when you try to invoke the non-static method startsWith of class String without an instance    String startsWith  Hello      What you need is to have an instance and then invoke the non-static method    String greeting   new String  Hello World     greeting startsWith  Hello       returns true    So you need to create and instance to invoke it

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It is not possible to call non-static method within static method  The logic behind it is we do not create an object to instantiate static method  but we must create an object to instantiate non-static method  So non-static method will not get object for its instantiation inside static method  thus making it incapable for being instantiated

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You can t get around this restriction directly  no   But there may be some reasonable things you can do in your particular case   For example  you could just  new up  an instance of your class in the static method  then call the non-static method   But you might get even better suggestions if you post your class es  -- or a slimmed-down version of them

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Firstly create a class Instance and call the non-static method using that instance  e g    class demo        public static void main String args              demo d   new demo            d add 10 20          to call the non-static method            public void add int x  int y            int a   x          int b   y          int c   a   b          System out println  addition    c

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The easiest way to use a non-static method field within a a static method or vice versa is      To work this there must be at least one instance of this class   This type of situation is very common in android app development eg - An Activity has at-least one instance   public class ParentClass   private static ParentClass mParentInstance   null   ParentClass      mParentInstance   ParentClass this                 void instanceMethod1        static void staticMethod1                mParentInstance instanceMethod1        public static class InnerClass        void  innerClassMethod1              mParentInstance staticMethod1              mParentInstance instanceMethod1                     Note - This cannot be used as a builder method like this one       String valueOf 100

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The only way to call a non-static method from a static method is to have an instance of the class containing the non-static method   class A       void method                 class Demo       static void method2                 A a new A             a method                     void method3                 A a new A            a method                      public static void main String args                  A a new A              an instance of the class is created to access non-static method from a static method            a method             method2               method3   it will show error non-static method can not be  accessed from a static method

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Constructor is a special method which in theory is the  only  non-static method called by any static method  else its not allowed

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There are two ways    Call the non-static method from an instance within the static method  See fabien s answer for an oneliner sample    although I would strongly recommend against it  With his example he creates an instance of the class and only uses it for one method  only to have it dispose of it later  I don t recommend it because it treats an instance like a static function   Change the static method to a non-static

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I use an interface and create an anonymous instance of it like so   AppEntryPoint java  public interface AppEntryPoint       public void entryMethod        Main java  public class Main       public static AppEntryPoint entryPoint       public static void main String   args                entryPoint   new AppEntryPoint                            You now have an environment to run your app from               Override             public void entryMethod                                   Do something                    System out println  Hello World                                      entryPoint entryMethod               public static AppEntryPoint getApplicationEntryPoint                 return entryPoint            Not as elegant as creating an instance of that class and calling its own method  but accomplishes the same thing  essentially  Just another way to do it

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public class StaticMethod       public static void main String   args throws Exception          methodOne               public int methodOne            System out println  we are in first methodOne            return 1            the above code not executed because static method must have that class reference   public class StaticMethod      public static void main String   args throws Exception           StaticMethod sm new StaticMethod            sm methodOne               public int methodOne            System out println  we are in first methodOne            return 1            This will be definitely get executed  Because here we are creating reference which nothing but  sm  by using that reference of that class which is nothing  but  StaticMethod new Static method    we are calling method one  sm methodOne       I hope this will be helpful

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It sounds like the method really should be static  i e  it doesn t access any data members and it doesn t need an instance to be invoked on   Since you used the term  static class   I understand that the whole class is probably dedicated to utility-like methods that could be static   However  Java doesn t allow the implementation of an interface-defined method to be static  So when you  naturally  try to make the method static  you get the  cannot-hide-the-instance-method  error   The Java Language Specification mentions this in section 9 4   Note that a method declared in an interface must not be declared static  or a compile-time error occurs  because static methods cannot be abstract     So as long as the method is present in xInterface  and your class implements xInterface  you won t be able to make the method static   If you can t change the interface  or don t want to   there are several things you can do    Make the class a singleton  make the constructor private  and have a static data member in the class to hold the only existing instance  This way you ll be invoking the method on an instance  but at least you won t be creating new instances each time you need to call the method  Implement 2 methods in your class  an instance method  as defined in xInterface   and a static method  The instance method will consist of a single line that delegates to the static method

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The only way to call a non-static method from a static method is to have an instance of the class containing the non-static method   By definition  a non-static method is one that is called ON an instance of some class  whereas a static method belongs to the class itself

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You can call a non static method within a static one using  Classname class method

[java] Calling Non-Static Method In Static Method In Java

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