Java flashcards, generated for you.

`==` compares object references (memory addresses); `.equals()` compares the actual string content. Use `.equals()` for string content comparison.

`null` is a special literal value representing the absence of an object reference. Variables can be assigned `null`, but calling methods on `null` throws `NullPointerException`.

Primitives (int, boolean, double, etc.) store values directly on the stack; references (objects, arrays, strings) store memory addresses pointing to heap data.

Autoboxing automatically converts primitives to their wrapper classes (Integer, Boolean, etc.) and vice versa (unboxing). This is syntactic sugar introduced in Java 5.

The `null` is converted to the string "null", resulting in "Value: null". No exception is thrown.

`final` prevents modification (variables, methods, classes); `finally` is a block that executes after try/catch; `finalize()` is a deprecated method called by garbage collector before object destruction.

Checked exceptions must be declared in the method signature or caught (IOException, SQLException); unchecked exceptions (RuntimeException subclasses) do not require declaration or catching (NullPointerException, ArrayIndexOutOfBoundsException).

Post-increment (`x++`) returns the old value; pre-increment (`++x`) returns the new value. The evaluation order and side effects make this undefined behavior in Java—avoid relying on it. The actual result depends on JVM optimization.

`ArrayList` is a resizable, dynamic collection (reference type) in java.util; arrays have fixed size. `ArrayList` uses `.add()` and `.get()`; arrays use index notation. `ArrayList` is slower but more flexible.

Java passes objects by value—the reference itself is copied, not the object. Changes to the object's fields affect the original; reassigning the reference parameter does not affect the original variable.