Java - Java vs C and C++

A very common exam question: why is Java called a dynamic language while C and C++ are called static? The answer is about when memory is allocated for variables.

In Java, primitive variables get memory when their object is created at run time. That is why Java is a dynamic programming language.

The classic material explains these differences one by one. Learn each one — they are favourite interview questions.

A) Pre-Processor and header files vs packages

C and C++ keep their ready-made library in header files (.h), and you include them with #include<>. The Pre-Processor loads those header files at compile time — this is called Static Loading.

Java keeps its ready-made library in packages (like java.io), and you import them. The compiler only checks that the package exists — it does not load anything. The JVM loads the classes only at run time when it actually needs them. This is called Dynamic Loading.

B) #include vs import — Question and Answer

C) Pointer variables vs Reference variables

C and C++ have pointers — variables that store the memory address. Java removed pointers for safety, and instead uses reference variables, which store a safe object reference value (a hex form of the object's unique hash code given by the heap manager).

This is why Java is called safer: no pointer can accidentally point to wrong memory and crash the system.

D) Destructors — not needed in Java

C++ needs a destructor — a method the developer writes to destroy objects and free memory. In Java, the Garbage Collector automatically destroys unused objects. So the developer never writes a destructor.

E) Operator overloading is not supported

In C++, you can give a new meaning to an operator (like +) for your own classes. Java does not allow developers to overload operators, because it is confusing and rarely needed. However, Java itself has pre-defined the + operator to work both for addition (10 + 20) and for joining strings ("a" + "b").

F) Java follows only Call By Value

When you pass a value to a method, C/C++ can pass it by value (a copy) or by reference (the address). Java passes only by value — it always gives a copy.

• Passing a primitive (int, float...) → a copy of the value is passed.
• Passing an object reference → a copy of the reference is passed (so the method can change the object, but cannot swap the caller's reference).

Remember the exam line: "Java is always Call By Value, never Call By Reference."

G) Memory sizes are fixed in Java

Because Java fixes the size of every primitive type on every platform, a Java program behaves the same everywhere — this is part of portability.

H) UNICODE — why Java characters need 2 bytes

C and C++ store characters using ASCII, which needs only 1 byte. Java uses the UNICODE system, which can represent characters of every language — English, Hindi, Chinese, Japanese and many more. One byte is not enough for that, so Java gives 2 bytes to every char.

The great advantage: a Java application can easily support many languages — this is the base of Internationalization (I18N), which we study fully in Chapter 18.