Java Basics

Question 1

Who owns Java?

Answer 1

Oracle

Question 2

What two programming languages are most similar to Java?

Answer 2

C++ and C#

Question 3

What type of programming language is Java?

Ex. Logic programming, scripting programming

Answer 3

An object-oriented language

Question 4

Is Java a proprietary, closed source, open source, or free software?

Answer 4

Open source

Question 5

What year was Java created?

Answer 5

1995

Question 6

Every line of code that runs in Java must be inside a ___?

Answer 6

class

Question 7

Should a class always start with an upper case or lower case letter?

Answer 7

Upper case

Question 8

Would Java read these as being the same? “MyClass” and “myclass”

Answer 8

No, Java is case sensitive

Question 9

What’s a statement in Java?

Answer 9

A statement is a complete instruction terminated by a semicolon.
Ex.
“x = 5 + 5;” is a statement

Question 10

What’s an expression in Java?

Answer 10

An expression is a combination of operators, literals, method calls, constants, and variables. It does not include data types or semicolons. Expressions are part of statements.
Ex.
Double “x = 5 +5”;
System.out.println(““this is an expression””)

Question 11

What can expressions can do?

Answer 11

Produce a value: int “x = 1+1”;

Assign a variable: int “v = 10” ;

Produce no result but might have a side effect. Side effects occur when an expression changes the value of any of its operands. Ex.
int “product = a * b” ;

The only variable changed in this expression is product, a and b are not changed. This is called a side effect

Question 12

What are the three types of Java statements?

Answer 12

Expression statements
Declaration statements
Control-flow statements

Question 13

What do declaration statements do?

Answer 13

They declare variables ex. x = 5;

Question 14

What do control-flow statements do?

Answer 14

They determine the order that statements are executed

Question 15

Can variables created in a code block be used outside of the code block?

Answer 15

No, variables created in a code black can only be used in the same code block

Question 16

Can you call a method above were it is defined?

Answer 16

Yes, unlike variables you can call methods before the method appears in your code

Question 17

What’s a code block?

Answer 17

All code inside { }

Question 18

In IntelliJ, what does a light grey method mean?

Answer 18

That it is not being used

Question 19

What’s a parameter?

Answer 19

The values that are apart of a functions header
Ex.                                              
                                                 //A &   B   are parameters
public static int Example (int a, int b) {
    return a + b;
}

Question 20

What’s an argument in Java?

Answer 20

When a function is called, the values that are passed in the call are arguments. Also called actual parameters.
Ex.
public static void main (String[ ] args) {

    int x = 2;
    int y = 5;
                                   //X & Y are the arguments
    int sum = multiply (x, y);

Question 21

Can you put a method into a variable?

Answer 21

Yes

Question 22

Should methods be created outside, or inside of the main method?

Answer 22

Outside. You then can call methods inside of the main method that are created outside of the main method.

Question 23

In what area should you call methods?

Answer 23

Inside the main method

Question 24

In the code, what is some unnecessary code that can be deleted?

if (score >= 1000) {
    return 1;
} else if (score >= 500 &amp;&amp; score < 1000) {
    return 2;
} else {
    return 3;
}

Answer 24

” && score < 1000”
“ else {“
return 3;
Resin being is the second if condition of “score < 1000” will always be true.
And
Reason for removing “else {“ is that in if statements, the last line of code will run if all statements above are false.

Question 25

What's method overloading?

Answer 25

When you create two methods with the same name (with different parameters)

Question 26

What is concatenation?

Answer 26

When you use the + symbol to add strings together

Question 27

What's a char?

Answer 27

A single character ex. "F"

Question 28

Can you declare (create) a constant / static variable inside a method?

Answer 28

No it must be declared outside of a method

Question 29

``` Which of these formats should a constant be declared? A. CONSTANT_VARIABLE B. Constant_Variable C. constant_variable D. constantVariable ```

Answer 29

A. CONSTANT_VARIABLE This is pretty much the universal way of writing a constant. You can technically write it however you want though, but it'd be a bit like wRItInG lIKe tHiS.

Question 30

What 4 primitive types can be used with switch statements?

Answer 30

byte, short, char, and int

Question 31

Do you define a char with ' ' or " "?

Answer 31

' ' why? I don't know but characters are defined with " "

Question 32

What can you do to make a value of "24.0048630" print a double with only two decimal numbers?

Answer 32

String.format("%.2f", double value)

Question 33

What is this new line of code doing? What are three things it can be called? House blueHouse = new House ("blue");

Answer 33

It's creating a new variable called 'blueHouse' , which is also a new instance of the 'House' class. The code is also called a reference meaning it's referencing to the House class. So that code can be called a new variable, instance, or reference. Also it assigns blue to blueHousre