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:

Java has a shorthand operator for these kinds of assignment statements

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...

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;

*=   Multiplication 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:

• Java has shorthand operators to increment and decrement a variable by 1 (one).

1. x = x + 1;

and

2. x = x - 1;

x is a variable in the program

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)