Home/ Questions/How to fix “no enclosing instance of type is accessible”.
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Teddy Brown
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Asked: 2022-05-18T19:39:46+00:00 In:

How to fix “no enclosing instance of type is accessible”.

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I’m trying to run a new project. I do a couple of things like this:

class Hello {
  class Thing {
  public int size;
 
  Thing() {
  size = 0;
  }
  }
 
  public static void main(String[] args) {
  Thing thing1 = new Thing();
  System.out.println("Hello, World!");
  }
 }

But in my program, I am getting the warning:

No enclosing instance of type Hello is accessible

Can someone explain why the “no enclosing instance of type is accessible” issue happened? Where have I gone wrong? Thank you!

no enclosing instance of type
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2 Answers

  1. Best Answer
    Expert

    The cause:

    From your program I found that the class of Thing was declared as a non-static inner class. This implies that it must be connected to a Hello class instance. You are attempting to build a Thing instance from a static context in your code. However, static methods did not have permission to access to a non-static inner class. This is the reason for your mistake.

    Solution:

    static class Thing can solve your problem and help your program run well. A specific Hello instance must be in scope for new Thing() to work if you have specified Thing as an inner class, which is linked to a specific instance of  Hello by definition (even if you never use or refer to it). If you declare it as a static type rather than a dynamic class, it will become “nested”, and you do not need a Hello instance.

    • 0

  2. The class Thing has been declared as an inner non-static class. This means that it must be associated to an instance of Hello class.

    You are trying to create a Thing instance from a static context. This is what the compiler is complaining.

    There are many possible solutions. Depending on your goals, there are a few options.

    • Move Thing from the Hello classification.

    • Thing should be changed to static nested classes. 

      static class Thing

    • Before creating an instance Hello, create . 

      public static void main(String[] args)
{
 Hello h = new Hello();
 Thing thing1 = h.new Thing(); // hope this syntax is right, typing on the fly :P
}

    If Thing relied on Hello for meaning, the last solution (a nonstatic nest class) would be mandatory. If we had: 

    public class Hello {
 public int enormous;

 public Hello(int n) {
 enormous = n;
 }

 public class Thing {
 public int size;

 public Thing(int m) {
 if (m > enormous)
 size = enormous;
 else
 size = m;
 }
 }
 ...
}

    Any attempt to create an object from class Thing raw, such as: 

    Thing t = new Thing(31);

    It would be difficult to test 31 against it, as there isn’t an obvious enormous value. To provide this h.enormous value, an instance h from the Hello outer classes is required: 

    ...
Hello h = new Hello(30);
...
Thing t = h.new Thing(31);
...

    It doesn’t necessarily mean a Thing if it does not have a Hello.

    For more information about inner/nested classes, see Nested Class (The Java Tutorials).

    • 13

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