Stores whole numbers, positive or negative (such as 123 or -456), without decimals. Valid types are byte, short, int and long. Which type you should use, depends on the numeric value.

is a statement that can convey a value. Some of the most common are mathematical, such as in the following source code example: int number = 4; int anotherNumber = number; int product = number * anotherNumber;

Name The variable name must follow rules for identifiers.

can store whole numbers from -32,768 to 32,767.

this line of code correct? System.out.println("The area is " + String.format(%.2f, area) + ".");

The “precision of float” is only six(6) or seven(7) decimal digits, while “double variables” have a precision of about “15 digits”. Therefore it is safer to use double for most calculations.

Identifiers cannot use Java keywords like class, public, void, etc.

type is used to store a single character. The character must be surrounded by single quotes, like 'A' or 'c':

can store whole numbers from -2,147,483,648 to 2,147,483,647. In general, the int data type is the preferred data type when we create variables with a numeric value.

Java Identifiers Best Practices: For names of methods and variables

used to check the relationship between two operands.

Is this a valid variable name? _option

Examples of non-primitive types are Strings, Arrays, Classes, Interface, etc.

can store fractional numbers from 1.7e−308 to 1.7e+308.

Is this a best practice and recommended code for declaration? int inputNumber;

Data types are divided into two groups: Primitive data types Non-primitive data types

Identifiers can be short names (like x and y) or more descriptive names (age, sum, totalVolume). It is recommended to use descriptive names in order to create understandable and maintainable code.

There are no errors in this code snippet. if(age >= 18) { System.out.print("Adult"); } else { System.out.print("Minor"); }

Solve the expression, is the answer correct? double number; number = 20 / 2 * 4 - 2 + 10 - (-2); System.out.println(number); 50

Java Identifiers Best Practices: For names of constant

Is this line of code correct? System.out.println("I love Java\nprogramming.\n");

int answer; answer = 30 - 20 / 10 / 3 + 100 / 2; System.out.println(answer); The answer is 80.

type is used to store a sequence of characters (text). String values must be surrounded by double quotes.

type can store whole numbers from 9,223,372,036,854,775,808 to 9,223,372,036,854,775,807. This is used when int is not large enough to store the value.

The general rules for constructing names for an identifier (unique identifiers) are: Identifiers must begin with either a letter, an underscore “_”, or a dollar sign “$”. Letters may be lower or upper case. Subsequent characters may use numbers 0 to 9.

are used to check whether an expression is true or false. If the expression is true, it returns 1 whereas if the expression is false, it returns 0.

Is this line of code correct? public Static void main(String[] args) { }

Is this line of code correct? if(console.hasNextDouble() == true):

Solve the expression, is the answer correct? int number; number = 10 - 4 + 8 / 4 * 2; System.out.println(number); The answer is 10.

Represents numbers with a fractional part, containing one or more decimals.

types are called reference types because they refer to objects.

What are the two tyoes of floating data types:

is an item of data used to store the state of objects.

double answer; answer = 12 - 20 / 4 + 10 % 2 + 6 % 2 - 1; System.out.println(answer); The answer is 6.0double answer; answer = 12 - 20 / 4 + 10 % 2 + 6 % 2 - 1; System.out.println(answer); The answer is 6.0

can store fractional numbers from 3.4e−038 to 3.4e+038.

Solve this expression, is the answer correct? int answer; answer = 50 * 2 - 15 / 3 + 10 % 2 + 6; System.out.print(answer); The answer is 101.

Java Identifiers Best Practices For names of classes

can store whole numbers from -128 to 127. This can be used instead of int or other integer types to save memory when you are certain that the value will be within -128 and 127.

are used to perform common mathematical operations.

Is this a best practice and recommended code for declaration of variable? int secondInput;

Avoid using underscores at the start of the identifier such as _read or _write.

Solve this expression, is the answer correct? int answer; answer = 40 - 10 / 5 * 6 / 3 + 100 / 2; System.out.print(answer); The answer is 76.

type is declared with the boolean keyword and can only take the values true or false.

are used with only one operand.

are used to assign values to variables.

Is this line of code correct? length = input.nextFloat();

Solve the expression, is the answer correct? double number; number = 40 - 10 / 5 * 6 / 3 + 100 / 2; System.out.println(number); The answer is 86.

specifies the size and type of variable values, and it has no additional methods.

Is this a best practice and recommended code for a class name? PrimeNumbers

Solve the expression, is the answer correct? double number; number = 50 + 10 / 5 * 6 / 2 + 100; System.out.println(number); The answer is 156.0

are tokens that represent names of variables, methods, classes, and other user-defined program elements. All Java variables must be identified with unique names.

is an attribute of data which tells the compiler or interpreter how the programmer intends to use the data.

is a symbol that tells the compiler to perform specific mathematical or logical manipulations. Java is rich in built-in operators and provide the following types of operators: 1. Unary Operators 2. Arithmetic operators 3. Assignment operators 4. Relational operators 5. Logical operators

Is this a valid variable name? number1

determines the type of value that the variable can hold.