Overview

The programing language Team 5901 uses is Java.
The goal is to provide students basic Java knowledge to survive build season.

This is NOT a comprehensive guide on Java - refer to online guides for a more detailed guide,

Commenting code

Comments can be used to document code, but can also be used to ignore parts of code.
Single-line comments start with two forward slashes (//).
Multi-line comments start with /* and ends with */.

// This is a comment
System.out.println("Hello World");

/* everything between these are comments
also part of a comment
*/

Variables & Data Types

In Java, variables store data values.
Different data values are represented by different Data Types.
Data types represent different kinds of variables.
Some variables store numbers, other stores text, etc.

To create a variable, the following syntax is used:

<type> <variable name> = <value>;

A few of the common ones we will use can be seen below:

Data Type	Description	Example Declaration
int	stores integers	int age = 5;
double	stores fractional numbers	double cost = 3.5;
boolean	stores true or false	boolean LightOn = true;
String	Stores text, surrounded by double quotes	String Name = "Cougar Pack";

Math Functions

Sometimes, our algorithm will require us to make calculations.
Here are some common functionss we may use:

Function	Description	Example Usage
Math.max(x,y)	returns the maximum of x and y	Math.max(20,5) would be return as 20
Math.min(x,y)	returns the minimum of x and y	Math.min(20,5) would be return as 5
Math.sqrt(x)	returns the square root of x	Math.sqrrt(100) would be return as 10
Math.abs(x)	reutnrs absolute value of x	Math.abs(-100) would return 100

Operators

Operators perform operations on variables and values.
Here are some common operators we may use:

Arithmetic Operators

Operator	Description	Example Usage
+	addition	5+3 returns 8
-	subtraction	5 - 3 returns 2
*	multiplication	5* 3 returns 15
/	division	5/3 returns 1.66
%	modulous (remainder)	5%3 returns 2

Comparison Operators

Comparison operators compare two values. The result is returned as a boolean (true or false)

Operator	Description	Example Usage
==	Equal to	5 == 3 would return false
!=	Not Equal	5 != 3 would return true
>	Greater than	5 > 3 would return true. 5 > 5 would return false.
<	Less than	5 < 3 would return false. 5 < 3 would return false.
>=	Greater than or equal to	5 >= 3 would return true. 5 >= 5 would return true.
<=	Less than or equal to	5 < 3 would return false. 5 <= 5 would return true.

Comparison Operators

Logical operators are used to determine logic between variables

Operator	Description	Example Usage
&&	AND - returns true if both statements are true	(5 > 3) && (6 > 6) would return false
&	&
!	NOT - returns true if false, return false if true	!(5 > 3) would return false

If-else

If-elses are used for control logic

if (condition1) {

}
else if (condition2) {

}
else {


}

Example:

int grade = 75;

if (grade > 90){     
    system.out.println("Grade is an A");
}
else if (grade > 80){
    system.out.println("Grade is an B");
}
else if (grade > 70){
    system.out.println("Grade is an C");
}
else if (grade > 60){
    system.out.println("Grade is an D");
}
else {
    system.out.println("Grade is an F");
}

Methods

A method is a block of code which only runs when it is called.
Arugments can be passed into methods, similiarly to a math function such as f(x) = 5x, where different values of x can be passed for different answers.
This allows methods to be reused - you dont need seperate lines of code for controlling different motor speeds!

Syntax

public <return type> <method name>(datatype argument){

}

In the following example, the method below can be used to make a robot drive forward, drive backwards, OR stop completely!

Example

public void elevatorMove(double power){
    elevatorMotor(power);
    System.out.println("Running elevator at" + power;
}

Later, this method can be called in multiple ways to have different functions:

arcadeDrive(1.0) // robot drives forward
arcadeDrive (0.0) // robot stops
arcadeDrive(-1.0) // robot drives backwards

This is equivalent to running the following:

elevatorMotorPower(1.0);
System.out.println("Running elevator at" + 1.0);
elevatorMotor(0.0);
System.out.println("Running elevator at" + 0.0);
elevatorMotor(-1.0);
System.out.println("Running elevator at" + -1.0);