Data Types and Conditional Statements - Learning Java Through Games - page 25

true

if (condition) {

false

} else {

}

FIGURE 2.6: The if-else construct.

TABLE 2 . 2 :

Java comparison

operators.
Operator Meaning Example

== equal 3 == 3

> = greater or equal 3 > =3

> greater 4 > 3

< smaller 3 < 5

< = smaller or equal 3 < =3

! = different 5! = 3

The operators = and == are very different. For example, the statement i=3
assigns the value of 3 to the integer i . Conversely, the condition (i == 3) checks if
the value of i is equal to 3. Remember to never use a single equality inside a condition.
Inside a conditional statement, always use double equality.

The operator == returns true when the two operands are equal. Conversely, the oper-
ator != returns true when the two operands are distinct. For example, the last two lines of
our code can be rewritten as follows.

if (z != x ∗ y) {
System. out . println ( "You need more practice" );

} else {

System. out . println ( "Congratulations!" );

}

Note that it is not required that an if statement has an else part; see Figure 2.7. For
example, the last two lines of our program can be rewritten as follows.
if (z == x {

System. out . println ( "Congratulations!" );
return ;
System. out . println ( "You need more practice" );
The statement return simply terminates the method. A return statement inside the
main method terminates the program. Therefore, the last line of code in the above code
snippet will only be executed when z is different from x

y)

∗

y .The if-else construct may
become dicult to understand when there are multiple if and if-else statements nested

∗