1-C: Data Types & Operations
We will learn to solve simple problems with Java programming. We will create all sorts of variables, test their limitations and exercise basic control flow.
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We will learn to solve simple problems with Java programming. We will create all sorts of variables, test their limitations and exercise basic control flow.
Last updated
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Was this helpful?
I can declare variables of common Java data types and assign values.
I can control the flow of my app with loops, conditionals and method calls.
I can write efficient conditionals and return comparisons in my methods.
I can describe the difference between logic, run time and compile time errors.
Primitives are objects that live entirely in stack memory (they're lowercase like int and not like String) . We'll go over the difference between stack and heap memory later. For now, just think of stack memory as the lightweight stuff that's really fast-access. Take a look at the types of Java primitives.
CompoundCapitalize name of classes
camelCase variables and methods
ALLCAPS variables marked as final, meaning they can't change
snake_case is typically used only in Python and I miss it every time I work in Java or C#
Operator
Description
Example (a=10, b=20)
+ (Addition)
Adds values on either side of the operator.
a + b will give 30
- (Subtraction)
Subtracts right-hand operand from left-hand operand.
a - b will give -10
* (Multiplication)
Multiplies values on either side of the operator.
a * b will give 200
/ (Division)
Divides left-hand operand by right-hand operand.
b / a will give 2
% (Modulus)
Divides left-hand operand by right-hand operand and returns the remainder.
b % a will give 0
++ (Increment)
Increases the value of operand by 1.
b++ gives 21
-- (Decrement)
Decreases the value of operand by 1.
b-- gives 19
What's 9 / 4? In Java, it's just2, but if you wrote it like 9.0 / 2, then the answer would be 2.5. If you don't introduce a decimal to the operation, if you only give Java literal ints , it'll match that format and ignore decimals.
We evaluate / test data and produce a true or false value.
Operator
Description
Example (a=10, b=15)
Result
==
Equality operator
a==b
false
!=
Not Equal to operator
a!=b
true
>
Greater than
a>b
false
<
Less than
a<b
true
>=
Greater than or equal to
a>=b
false
<=
Less than or equal to
a<=b
true
You can declare and initialize an int like int x = 5; Similarly, you can create an array that contains three ints like this: int[] x = {5, 10, 15};
// Let's demonstrate some array skills!
// Here's a blank array that's got spots for five ints
int[] arr = new int[5];
// You can also create an array with initial values
int[] x = {5, 10, 15}; x.length; // note: this isn't a method like it is in the String class.
x[0]; // this will print "5" in my example
x[x.length-1]; // this will print "15" in my example
Loop through every element in the array
Check if an element is found in an array
Make an array of other types of objects
This is a part of control flow. The thread, the computer's train of thought, is being sent over to work through a set of commands called a method or function (either name works in this class).
