Syntax Reference

Here you’ll find a quick reference to some basic java syntax.

Built-In Data Types

• String - Stores text, such as “Hello”. String values are surrounded by double quotes.
• int - stores integers (whole numbers), without decimals, such as 123 or -123.
• double - stores floating point numbers, with decimals, like 19.99 or -3.14159265. Double values end with d. (for people with experience, we will not be using float in our code).
• char - stores single characters, such as ‘a’ or ‘B’. Char values are surrounded by single quotes
• boolean - stores values with two states: true or false

Variables

type variableName = value;

Assignment:

variableName = newValue;

Example:

String greeting = "Hello World";
double treeHeight = 12.2d; // meters
int funnyNumber = 67;
funnyNumber = 41;          // funnyNumber is now 41

Logic

Operators

• <, >: Less than, Greater than
• <=, >=: Less than or equal to, Greater than or equal to
• ==: Equivalent to
• !=: Not equivalent to
• !: Not (inverts any boolean after it, so true->false and vice-versa)
• &&: And (True: (1 == 1) && (2 == 2), checks if 1 is equal to 1 and 2 is equal to 2)
• ||: Or (True: (1 == 1) || (2 != 2), checks if 1 is equal to 1 or 2 is equal to 2)

If Statements:

if (condition1) {
    // Runs if condition1 is true
} else if (condition2) {
    // Runs if condition1 is false but the 2nd condition is true
} else {
    // Run if condition1 is false and condition2 is false
}

Classes and Functions

Classes need to be named according to the file name and must use a capital letter at the start

class Car {
    private double speed = 0;

    public boolean isMoving() {
        return speed == 0;
    }

    public void accelerate() {
        speed += 1;
    }
    
    public void decelerate() {
        speed -= 1;
    }
}

• public: Accessable from instances of class and inside of its methods

• private: Only accessable from inside the class’s methods

Functions:

modifiers reutrn_type function_name(argument_1_type arg1, arg_2_type arg2) {
 return return_type;
} 

Ex.:

public double add(double number1, double number2) {
 return number1 + number2;
}