Java Error Non-static Variable Cannot Be Referenced From Static Context
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Non-static Variable This Cannot Be Referenced From A Static Context Inner Class
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Non Static Field Cannot Be Referenced From A Static Context Android
us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just non static method cannot be referenced from a static context java error like you, helping each other. Join them; it only takes a minute: Sign up non-static variable this cannot be referenced from a static context [duplicate] up vote 16 down vote favorite 2 This question already has an answer here: Non-static variable cannot be referenced from a static context 10 answers I'm new to Java from Ruby how to access non static variable in static method java background, I made a simple code to test the class and object of Java public class ShowBike { private class Bicycle { public int gear = 0; public Bicycle(int v) { gear = v; } } public static void main() { Bicycle bike = new Bicycle(5); System.out.println(bike.gear); } } it gives me an error in the compiling process: ShowBike.java:12: non-static variable this cannot be referenced from a static context Bicycle bike = new Bicycle(5); ^ 1 error any idea? update after reading all the helpful answer here, I feel the static nested class behave the same as a class in a different file in the same package test/Bicycle.java package test; public class Bicycle { public static int wheels = 2; public int gear = 0; public Bicycle(int v) { gear = v; } } test/Launcher.java package test; public class Launcher { public static void main(String[] args) { Bicycle bike = new Bicycle(5); System.out.println(bike.gear); System.out.println(Bicycle.wheels); System.out.println(bike.wheels); } } Am I correct on this point? java oop nested-class
cannot be referenced from a static context? "non-static variable cannot be referenced from a static context" is biggest nemesis of some one who has just started programming and that too in Java. Since main method in java is most popular method among all beginners
Non Static Variable Cannot Be Referenced From A Static Context Netbeans
and they try to put program code there they face "non-static variable cannot be referenced non static method cannot be referenced from a static context android from a static context" compiler error when they try to access a non static member variable inside main in Java which is static.
Non Static Variable In Static Method C#
if you want to know why main is declared static in Java see the link. public class StaticTest { private int count=0; public static void main(String args[]) throws IOException { count++; //compiler error: non-static variable http://stackoverflow.com/questions/15331846/non-static-variable-this-cannot-be-referenced-from-a-static-context count cannot be referenced from a static context } } Why non static variable can not be called from static method Now before finding answer of compiler error "non-static variable cannot be referenced from a static context", let's have a quick revision of static. Static variable in Java belongs to Class and its value remains same for all instance. static variable initialized when class is loaded into JVM on the other hand http://javarevisited.blogspot.com/2012/02/why-non-static-variable-cannot-be.html instance variable has different value for each instances and they get created when instance of an object is created either by using new() operator or using reflection like Class.newInstance(). So if you try to access a non static variable without any instance compiler will complain because those variables are not yet created and they don't have any existence until an instance is created and they are associated with any instance. So in my opinion only reason which make sense to disallow non static or instance variable inside static context is non existence of instance. In summary since code in static context can be run even without creating any instance of class, it does not make sense asking value for an specific instance which is not yet created. How to access non static variable inside static method or block You can still access any non static variable inside any static method or block by creating an instance of class in Java and using that instance to reference instance variable. This is the only legitimate way to access non static variable on static context. here is a code example of accessing non static variable inside static context: public class StaticTest { private int count=0; public static void main(String args[]) throws IOException { StaticTest test = new StaticTest(); //accessing static variable by creating an instance
Challenge My question and problems are below the instructure. Here is instructure: Challenge Task 1 of 1 The method getTitleFromObject will be called and passed a String and/or a com.example.BlogPost. Return the object type casted as a String https://teamtreehouse.com/community/nonstatic-variable-object-cannot-be-referenced-from-a-static-context-java-data-structures-challenge if it is a String, and if it is the BlogPost type cast it, and return the results of the getTitle method. import com.example.BlogPost; public class TypeCastChecker { /*************** I have provided 2 hints for this challenge. Change `false` to `true` in one line below, then click the "Check work" button to see the hint. NOTE: You must set all the hints to false to complete the exercise. ****************/ public static boolean HINT_1_ENABLED = cannot be false; public static boolean HINT_2_ENABLED = false; public static String getTitleFromObject(Object obj) { // Fix this return statement to be the correct string. return ""; } } I tried a lot of ways. I got many errors but I figured out that "Editor wants String result" And I add if statement: if(obj instanceof String){ String object = (String) obj; } Also I define a variable as private static String object; and Editor said cannot be referenced "Try again!". There was no more answer. After that I got this problem. My latest code is: import com.example.BlogPost; public class TypeCastChecker { /*************** I have provided 2 hints for this challenge. Change `false` to `true` in one line below, then click the "Check work" button to see the hint. NOTE: You must set all the hints to false to complete the exercise. ****************/ public static boolean HINT_1_ENABLED = false; public static boolean HINT_2_ENABLED = false; public String object; public static String getTitleFromObject(Object obj) { // Fix this return statement to be the correct string. /* if(obj instanceof BlogPost){ String obj = (String) obj; } */ if(obj instanceof String){ String object = (String) obj; } return object; } } Thanks for any insight! PS: I want to know that why non-static variable object cannot be referenced from a static context? 5 Answers MOD Dan Johnson Treehouse Moderator 38,449 Points Dan Johnson Dan Johnson Treehouse Moderator 38,449 Points over 1 year ago A non-static variable can't be accessed from a static method as they don't have access to a reference to any instance of the class. As static methods are tied to the class itself, it wouldn't know which instance of the variable to use, if any even existed at the time. For the challenge: When you're assigning obj casted