Get type of an object with an object of null?

java, runtime, runtime-error

Solution

When you have

String b = null;

what you actually have is a variable of reference type `String` that is referencing `null`. You cannot dereference `null` to invoke a method.

With local variables you cannot do what you are asking.

With member variables, you can use reflection to find the declared type of the field.

Field field = YourClass.class.getDeclaredField("b");
Class<?> clazz = field.getType(); // Class object for java.lang.String

Problem

The following code does compile, but why do I get a run time exception? ``` String b = null; System.out.println(b.getClass()); ``` Error I get is ``` java.lang.NullPointerException ``` How can I get the type of the object even if it's set to null? Edit I realize there is no object present, but there still is an object b of type String. Even if it holds no object, it still has a type. How do I get at the type of an object, regardless of if it holds an object or if it does not.

Original source

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