Java is one of the top three most popular programming languages worldwide. It 's used extensively by business enterprises android apps games and if you learn java you could land a job as a java developer.
Java is one of the top three most popular programming languages worldwide. It 's used
extensively by business enterprises android apps games and if you learn java you could land a
job as a java developer. Entry-level java developers have an average starting salary of 70 000
that's nothing to sneeze at so why not learn java. A jdk is an acronym for java development
kit it contains developers tools to help us code as well as a jre a java runtime environment
which contains a library toolkits and our jvm which translates by code for us to machine
code. All you need to worry about is downloading a jdk and everything else will be included.
We need a unique name for this java project i will call this my first program and i will want
to configure the jre the java runtime environment and we downloaded that with the jdk. When
we compile this source code to bytecode we 're going to create a new file that has the dot
class file extension and with that bytecode file we can run that and translate it using a jvm a
java virtual machine.
This is our class mine is called main anything within the outer set of curly braces belongs to
the class and is contained within and within our class we have what is called a main method
our program wo n't run without this method because when we run our code we begin by
calling the main method so if we were to compile and run this code you can do so by clicking
the screenplay button. When i compile and run this pay attention the output is one long line of
text. After printing the first statement our cursor does not move down to the next line in order
to do so we could use a print ln statement short for print line it 's as if we're hitting enter when
we finish outputting our text. An alternative to using a print line statement is that we could
stick with the standard print statement and at the end of our text add an escape sequence for a
new character. Anything preceding with a backslash is the beginning of an escape sequence
and there 's one of a multitude of characters that could follow afterwards and depending on
the character this has special meaning for your compiler to do something specific now
anything that is following two forward slashes is beginning of a single line comment i could
write this is a comment and this line of text is going to be ignored by the compiler.
A shortcut would be to type system dot out then hold control space and your ide will auto
generate the rest of this print line statement for you. A trick on zooming in or out is how to
change the font color as well as the background color of your console window so with spaces
spaces do n't make much of a difference within your code. A variable is a placeholder for a
value and it behaves as the value that it contains. If we're going to store a value within a
variable we have to list the data type of what we 're planning to store within that variable is it
going to be a number a word a boolean so we need to discuss data types. A float data type can
store a fractional number up to six to seven digits. A double has more precision it uses eight
bytes of memory and it can store up to 15 digits. In comparison with a float this has less
precision than a double. The last data type is the string data type the size varies because these
are reference data types.
The largest number that you can store within an integer variable is just over 2 billion. With all
statements we follow this with a semicolon at the end the next step is called assignment we
will take our variable and assign it equal to some sort of value of the data type that we
declared this variable to be. that we're planning to store within this variable. A double can
store a number with a fractional portion with integers we can not store a decimal portion so
with a float or a float you would type in float for the data type let 's create a new variable like
y float y equals 3. 14. We also have booleans and characters char for short char and we don't
necessarily need to come up with a variable that only holds a single letter. In this video I 'm
going to teach you guys how we can swap two variables using Java using Java. X currently
has water and Y currently has kool-aid so what happens if we set X to equal Y well we're gon
na assign variable Y to variable X shit so I 'll just type in X colon space plus the variable X
and then let 's do the same thing for y so we 'll change X to Y.
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