Primitive Data Types

• Integer: int
• Floating Point: double or float
• Boolean: boolean or bool
• String: char/String or str

Java

int x = 5;
double y = 5.5;
boolean z = true;
String word = "Hello";
System.out.println(x + word) // what does this output?

Python

x: int = 5
y: float = 5.5
z: bool = True
word: str = "Hello"
print(x + word) # what does this output?

Java

int x = 5;
double y = 5.5;
boolean z = true;
String word = "Hello";
System.out.println(x + word) // "5Hello"

Python

x: int = 5
y: float = 5.5
z: bool = True
word: str = "Hello"
print(x + word) # what does this output?

Java

int x = 5;
double y = 5.5;
boolean z = true;
String word = "Hello";
System.out.println(x + word) // "5Hello"

Python

x: int = 5
y: float = 5.5
z: bool = True
word: str = "Hello"
print(x + word) # TypeError!

The data type determines how variables are treated.

Different data types
support different operations.

Custom Data Type - Enum

An enum is a list of named values.

from enum import Enum


class Grade(Enum):
    A = 1
    B = 2
    C = 3
    D = 4
    F = 5

public enum Grade {
    A,
    B,
    C,
    D,
    F;
}

Custom Data Type - Enum

An enum defines a new data type.

Java

Grade gradeA = Grade.A;
Grade gradeB = Grade.B;
student.setGrade(Grade.C);

Python

grade_a: Grade = Grade.A
grade_b: Grade = Grade.B
student.set_grade(Grade.C)

Classes define new data types composed of one or more other types.

This new data type is the state of the object built from the class.

Type Systems

• Java - Strong, Static Typing
• Python - Strong, Dynamic Typing

We are using Mypy to make Python act like a statically typed language.