Classes

What are the primitive data types?

What types exist in Java?

What is static?

What are the different access modifiers?

Describe the process of creating an instance of a class

Does new Integer(128) == 128?

What can you do with a variable holding null?

What is an enum?

What is the purpose of class loaders?

What are the default class loaders?

Overload vs override

How to write a singleton?

What is the difference between interface and @interface?

When does Class.getClassLoader return null?

How can you determine if A is a subtype of B?

What is the difference between interface and abstract class?

What if both implemented interfaces declare the same method?

How to write an immutable class?

How to use SPI?

How to launch another program from a Java application?