[java] Non-static variable cannot be referenced from a static context

It is ClassLoader responsible to load the class files.Let's see what happens when we write our own classes.

Example 1:

class StaticTest {

      static int a;
      int b;
      int c;
}

Now we can see that class "StaticTest" has 3 fields.But actually there is no existence of b,c member variable.But why ???. OK Lest's see. Here b,c are instance variable.Since instance variable gets the memory at the time of object creation. So here b,c are not getting any memory yet. That's why there is no existence of b,c. So There is only existence of a. For ClassLoader it has only one information about a. ClassLoader yet not recognize b,c because it's object not instantiated yet.

Let's see another example: Example 2:

class StaticTest {

      public void display() {
          System.out.println("Static Test");
      }


      public static void main(String []cmd) {

             display();       
      }

}

Now if we try to compile this code compiler will give CE error. CE: non-static method display() cannot be referenced from a static context.

Now For ClassLoader it looks like:

class StaticTest {

      public static void main(String []cmd) {

             display();       
      }

}

In Example 2 CE error is because we call non static method from a static context. So it is not possible for ClassLoader to recognize method display() at compile time.So compile time error is occurred.

Examples related to java

Under what circumstances can I call findViewById with an Options Menu / Action Bar item? How much should a function trust another function How to implement a simple scenario the OO way Two constructors How do I get some variable from another class in Java? this in equals method How to split a string in two and store it in a field How to do perspective fixing? String index out of range: 4 My eclipse won't open, i download the bundle pack it keeps saying error log

Examples related to variables

When to create variables (memory management) How to print a Groovy variable in Jenkins? What does ${} (dollar sign and curly braces) mean in a string in Javascript? How to access global variables How to initialize a variable of date type in java? How to define a variable in a Dockerfile? Why does foo = filter(...) return a <filter object>, not a list? How can I pass variable to ansible playbook in the command line? How do I use this JavaScript variable in HTML? Static vs class functions/variables in Swift classes?

Examples related to compiler-errors

intellij idea - Error: java: invalid source release 1.9 Error:Execution failed for task ':app:transformClassesWithJarMergingForDebug' Deserialize JSON with Jackson into Polymorphic Types - A Complete Example is giving me a compile error Android java.exe finished with non-zero exit value 1 error: expected primary-expression before ')' token (C) What does "collect2: error: ld returned 1 exit status" mean? Python3: ImportError: No module named '_ctypes' when using Value from module multiprocessing Maven error :Perhaps you are running on a JRE rather than a JDK? What does a "Cannot find symbol" or "Cannot resolve symbol" error mean? Operator overloading ==, !=, Equals

Examples related to non-static

invalid use of non-static member function Difference between Static methods and Instance methods C# error: "An object reference is required for the non-static field, method, or property" Non-static variable cannot be referenced from a static context Calling Non-Static Method In Static Method In Java