Theorical question about declaration/definition in java

Question

Hi, we know the difference between declaration and definition:
-declaration: no memory is allocated.
-definition: memory is allocated.
In C/C++ if we want to define a variable we can make
int x;or
int x = 5; (we assign a value too)
while, if we just want to declare we can make
extern int x;Is there a way in java to simply declare a variable? According to me just arrays can be declared with
String[] arrayString;while istructions like
String myString;are definition as they allocate at least a String reference on the stack...am I wrong?

Answer 1

Squall867 wrote:
Hi, we know the difference between declaration and definition:
-declaration: no memory is allocated.
-definition: memory is allocated.That's not the definition I learned, back when dinosaurs roamed the earth, men lived in caves and used pterodactyls for airplanes, and computers were made of rocks.
Is there a way in java to simply declare a variable? According to me just arrays can be declared withThis is a pretty meaningless question.
In Java, whenever you declare/define a variable (there is no distinction), space is allocated for that variable. It's at least 1 byte for a byte or boolean, at least 2 bytes for a char or a short, at least 4 bytes for an int, float, or reference, and at least 8 bytes for a double or long. A given JVM implementation may actually use more bytes for any given type for word-alignment performance optimization.
Is there a way in java to simply declare a variable? According to me just arrays can be declared with
String[] arrayString;
This declares a reference variable of type reference to array of String. It will occupy at least 4 bytes.
while istructions like
String myString;are definition as they allocate at least a String reference on the stack...am I wrong?This declares a reference variable of type reference to String. It will occupy at least 4 bytes.
Note that an array reference variable is no different than any other reference variable.
Also note that for any variable, whether it lives on the stack or on the heap depends only on whether it's a member variable or a local variable. If objects are allowed to be created on the stack in future versions of Java, that distinction will get slightly more complex.