Day 5 Of Our Month Of Java

Data Types And Operators

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I am looking ahead and not sure where my “Month of Java” is going to take me. I look at code that people are working on and think these small steps are just so far away from where I need to be. I’ll persevere though and see where this month takes me. I may need to look at changing my approach sooner or later.

What Did I Learn Today

• Data Types: A Data type defines the values a variable can take, eg; and int data type can only take integer values. The data type needs to be known at compile time, with two categories of data types available in Java:

1. Primitive data types: There are 8 primitive data types which are boolean, char, byte, short, int, long, float and double. The size of these data types do not change from one operating system to another where byte, short, int and long data types are used for storing whole numbers. Float and double are used for fractional numbers and char is used for storing characters(letters). Boolean data type is used for variables that holds either true or false.
2. Non primitive Data Types: Arrays and Strings are non-primitive data types.

• Operators: Operators represent an action for example; Basic arithmetic operators are: +, -, , /, %
  Assignments operators in java are: =, +=, -=, =, /=, %=
  num2 = num1 would assign value of variable num1 to the variable.
  num2+=num1 is equal to num2 = num2+num1
  num2-=num1 is equal to num2 = num2-num1
  num2=num1 is equal to num2 = num2num1
  num2/=num1 is equal to num2 = num2/num1
  num2%=num1 is equal to num2 = num2%num1

• Auto-increment and Auto-decrement Operators
  ++ and —
  num++ is equivalent to num=num+1;
  num–- is equivalent to num=num-1;

• Logical Operators
  Logical Operators are used with binary variables. They are mainly used in conditional statements and loops for evaluating a condition.
  Logical operators in java are:
  && - and
  || - or
  ! - not

• Comparison(Relational) operators
  We have six relational operators in Java:
  "==" equal to
  "!=" not equal to
  ">" less than
  "<" greater than
  ">=" less than or equal to
  "<=" greater than or equal to

When it comes to assignment operators, we will be seeing in the next few days where we start to use “if statements” and “loops”. We use these assignment comparison operators to determine if a condition is met, for example; if variable1 “is equal to” variable2.

Code For The Day

Let's test out our Arithmetic Operators in the following code example:

  1 public class ArithmeticOperatorDemo {
  2         public static void main(String args[]) {
  3                 int num1 = 100;
  4                 int num2 = 20;
  5 
  6                 System.out.println("num1 + num2: " + (num1 + num2));
  7                 System.out.println("num1 - num2: " + (num1 - num2));
  8                 System.out.println("num1 * num2: " + (num1 * num2));
  9                 System.out.println("num1 / num2: " + (num1 / num2));
 10                 System.out.println("num1 % num2: " + (num1 % num2));
 11         }
 12 }

Output

java ArithmeticOperatorDemo 
num1 + num2: 40
num1 - num2: 0
num1 * num2: 400
num1 / num2: 1
num1 % num2: 0

I'll be posting daily, sharing my experiences on my “1 Month of Java Code” experiences”, my previous post on day 4 can be found below, so feel free to have a look:
https://steemit.com/java/@run.vince.run/java-variables-for-day-4-of-30-days-of-java

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