Transcript Shorthand operators

Shorthand operators
Shorthand operators
• Shorthand operator:
• A shorthand operator is a shorter way to express
something that is already available in the Java
programming language
• Shorthand operations do not add any feature to the
Java programming language
(So it's not a big deal).
Shorthand operators +=, -=, *=, /= and *=
• A frequent construct is the following:
x is a variable in the program
x = x + value ; // Add value to the variable x
x = x - value ; // Subtract value to the variable x
x = x * value ; // Increase the variable x by value times
and so on...
Java has a shorthand operator for these kinds of assignment
statements
Shorthand operators +=, -=, *=, /= and *=
(cont.)
• Operator assignment short hands:
Operator
symbol
Name of the
operator
Example
Equivalent
construct
+=
Addition
assignment
x += 4;
x = x + 4;
-=
Subtraction
assignment
x -= 4;
x = x - 4;
*=
Multiplicatio
n assignment
x *= 4;
x = x * 4;
/=
Division
assignment
x /= 4;
x = x / 4;
%=
Remainder
assignment
x %= 4;
x = x % 4;
Shorthand operators +=, -=, *=, /= and *=
(cont.)
• Exercise: what is printed by the following program
public class Shorthand1
{
public static void main(String[] args)
{
int x;
x = 7;
x += 4;
System.out.println(x);
x = 7;
x -= 4;
System.out.println(x);
Shorthand operators +=, -=, *=, /= and *=
(cont.)
x = 7;
x *= 4;
System.out.println(x);
x = 7;
x /= 4;
System.out.println(x);
x = 7;
x %= 4;
System.out.println(x);
}
}
Shorthand operators +=, -=, *=, /= and *=
(cont.)
• Example Program: (Demo above code)
– Prog file:
http://mathcs.emory.edu/~cheung/Courses/170/Syllabus/04/Progs/
Shorthand1.java
• How to run the program:
• Right click on link and save in a scratch directory
• To compile: javac Shorthand1.java
• To run:
java Shorthand1 (You will see the
answers on the terminal)
Increment and decrement shorthand
operators
• Two very commonly used assignment statements are:
1. x = x + 1;
and
2. x = x - 1;
x is a variable in the program
• Java has shorthand operators to increment and decrement a
variable by 1 (one).
Increment and decrement shorthand
operators (cont.)
• Increment and decrement operators:
Operator
symbol
Name of the
operator
Example
Equivalent
construct
++
Increment
x++;
x = x + 1;
--
Decrement
x--;
x = x - 1;
Increment and decrement shorthand
operators (cont.)
• Exercise: what is printed by the following program
public class Shorthand2
{
public static void main(String[] args)
{
int x;
x = 7;
x++;
System.out.println(x);
x = 7;
x--;
System.out.println(x);
}
}
Increment and decrement shorthand
operators (cont.)
• Example Program: (Demo above code)
– Prog file:
http://mathcs.emory.edu/~cheung/Courses/170/Syllabus/04/Progs/
Shorthand2.java
• How to run the program:
• Right click on link and save in a scratch directory
• To compile: javac Shorthand2.java
• To run:
java Shorthand2 (You will see the
answers on the terminal)