Java Variables Explained

1:51

We'll break down one line of code to learn how a variable is declared, named, and assigned. We'll also get introduced to a data type known as "String", which is used to represent text data in Java.


Video Transcript

  • 0:00

    What you just typed out was a variable declaration and assignment.

  • 0:03

    In Java, you can think of a variable as a container

  • 0:06

    that you can name and store data in.

  • 0:08

    Variables are common to almost every programming language,

  • 0:11

    because it makes it easy to hold on to data

  • 0:13

    that you want to reuse later.

  • 0:15

    If you want to display a piece of data in multiple places,

  • 0:17

    variables make it easy,

  • 0:19

    because you only have to set the data in 1 place.

  • 0:22

    It also makes it really easy to change the data,

  • 0:24

    because we only have to change it in 1 place.

  • 0:26

    And then that change is reflected throughout the code.

  • 0:29

    The 1st word in this line of codes, string,

  • 0:31

    is the data type of the variable,

  • 0:33

    and it tells us what kind of data will be stored in the variable.

  • 0:35

    We'll look at a lot of different data types,

  • 0:38

    like numbers, yes-or-no values, and dates,

  • 0:40

    and in each case, there's a special key word like string

  • 0:43

    that tells the computer what kind of data to expect.

  • 0:45

    The second word is the name of the variable.

  • 0:48

    We can name variables whatever we want

  • 0:50

    according to a few basic rules:

  • 0:52

    Use letters and numbers, don't start with a number,

  • 0:55

    and don't use any special characters besides underscores.

  • 0:58

    Okay, so far, we have a variable named my name

  • 1:00

    that we set to hold string data,

  • 1:02

    so let's put a string in it.

  • 1:04

    In Java, as in many programming languages,

  • 1:07

    strings are represented as text surrounded by double quotes.

  • 1:11

    In this case, the text is my name,

  • 1:13

    and I make it a string by adding the quotes around it.

  • 1:16

    We then use the equal sign

  • 1:18

    to put the string into the variable, or in other words,

  • 1:20

    set my name equal to Ben.

  • 1:23

    Now the next thing you'll notice in this line is the semicolon.

  • 1:26

    Semicolons in Java are kind of like periods for sentences.

  • 1:30

    We use them to mark when we're done saying something.

  • 1:33

    Each statement or command in Java

  • 1:35

    must always end with a semicolon.

  • 1:37

    That tells the computer that we're done with this step

  • 1:39

    and ready to move on to the next one.

  • 1:42

    I think you're ready for a new code challenge.

  • 1:44

    Fix this line to set the favorite color variable

  • 1:46

    to your favorite color.

  • 1:48

    You might have to move some things around and add or change some text.

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Instructor

  • Ben Jakuben

    Ben is a father, husband, son, friend, and teacher. He is firmly committed to the belief that the world is evolving to a better place. Find him on Twitter @benjakuben.