24su ver.

Note: this is for the Summer 2024 iteration of CSE 121. Looking for a different quarter? Please visit https://courses.cs.washington.edu/courses/cse121/.

Structure of a Java program

public class Name {
    public static void main(String[] args) {
        statement;
        // more statements here...
        statement;
    }
}

Printing

(displays output in the console window)

Code Description
System.out.print("text"); prints text
System.out.println("text"); prints text and moves to a new line
System.out.println(); prints a blank line

Comments

(notes written in the program for the programmer to read)

/* text
 * (multiple lines)
 */

// text (one line)

Example

/* CSE 121, Stan Smith
 * This program prints the steps of my favorite recipe.
 */

// This code displays the preamble of the US Constitution.

Turtle Graphics

(allows you to draw graphics on a window)

Turtle donatello = new Turtle();

Example

Turtle donatello = new Turtle();
donatello.forward(100);

Turtle Methods

Method Description
donatello.forward(x); moves turtle forward by a distance of x pixels
donatello.left(deg); turns turtle left by deg degrees
donatello.right(deg); turns turtle right by deg degrees
donatello.up(); lifts pen up and stops drawing
donatello.down(); puts pen back down and starts drawing
donatello.penColor(color); sets pen color (String or Java Color) options: black, blue, cyan, gray, green, magenta, orange, pink, red, yellow

Example

Turtle donatello = new Turtle();
donatello.forward(100);