Java gurus -- look here please

Question

Is the integer -1 of type int or is it an union between an operand (-) and a positive number?

Answer 1

Compile this class. Command: javac Test116.java
class Test116 {
    public static void main(String[] args) {
        int x = -1;
}Use javap to disassemble the class.
C> javap -c -classpath . Test116
Compiled from Test116.java
class Test116 extends java.lang.Object {
    Test116();
    public static void main(java.lang.String[]);
Method Test116()
   0 aload_0
   1 invokespecial #1 <Method java.lang.Object()>
   4 return
Method void main(java.lang.String[])
   0 iconst_m1
   1 istore_1
   2 returnYou can see that the "main" method is composed from three instructions:
iconst_m1 -> it pushes the constant "-1" to the stack
istore_1 -> pops the top of the stack and stores it into the first local variable (x)
return -> return from the method.
So you can say that "-1" was translated into the constant "- 1".
But the compiler is smarter: try this program:
class Test116 {
    public static void main(String[] args) {
        int x = 9 - 10;
}9 - 10 is equal to -1. Use Javap and see that the output is exactly the same.