flour >= 4  true

sugar >= 2  false 

Logical Operators

Here is part of the program again:

// check that there are enough of both ingredients
if ( flour >= 4 && sugar >= 2 )
  System.out.println("Enough for cookies!" );
else
  System.out.println("sorry...." );

For you to have enough ingredients, both relational expressions must be true. This is the role of the && (and-operator) between the two relational expressions. The && requires that both

flour >= 4 

and

sugar >= 2 

are true before the entire expression is true. The entire question must be true in order for the true branch to execute.

The and operator && is a logical operator. A logical logical operator looks at true and false values and combines them into a single true or false.