Using Underscore in Numeric Literals Java

This is new Java feature introduced in Java 7 just to improve the readability of codes like we can use an Underscore character to separate digits in group of three,similar to how we would use a punctuation Mark like comma, or a space,as a seperatot.

For example; 

public class UnderscoreInLiteral

{

  public static void main(String args[])

  {

      int num = 1_00_00_000;

      System.out.println("Num:",num);

  

    long num1 = 1_00_00_000;

    System.out.println("Num",num1);

   }

}

Output:

10000000

10000000

Object Oriented Approach in Python

So Classes and Why do we need them

In Java it require that you write code in inside class but in Python it does not required.you can write a code inside a class but you don't have to.In Python we define a class using class keyword similar to define a function using def keyword.

Let's take an complete object-oriented example:

classess.py

students =[]

class Student:

      school_name = "Abhinaw Demo"
     
      def __init__(self,name,student_id=1):
              self.name=name
               self.student_id=student_id
                students.append(self)

      def __str__(self):
            return "Student "+ self.name

     def get_name(self):
            return self.name.capitalize()
    
      def get_school_name(self):
             return self.school_name

class NewSchoolStudent(Student):

    school_name="Inheritance Abhinaw Demo"
 
    def get_school_name(self):
          return "This is inheritance"

     def get_name(self):
         original_value= supper().get_name()
          return original_value + "New School"

abhinaw= NewSchoolStudent("Abhinaw")
print(abhinaw.get_school_name())
print(abhinaw.get_name())

This demo code includes classes,adding methods to our classes,Constructor,Instance and Class Attributes and Inheritance and Polymorphism.

Lambda Functions in Python

So Lambda Functions are just an anonymous function.they are very simple just saves your space and time.they are useful in case of higher  order function.Lets take an example:

def double(a):
        return a*2

Convert to Lambda Function

double = lambda a: a*2

Generator Functions - Yield Python

So Yield is a keyword.first let's take an example.

student = []

def read_file():
        try:
              f=open("students.txt","r")
               for student in read_students(f):
                      students.append(student)
               f.close()
         except Exception:
                print("Could not read file")

def read_students(f):
       for line in f:
              yield line

read_file()
print(students)

So what I have done is created a single function read_students and what it does
it iterated over the file and yield the single line from that file.

Opening,Reading and Writing Files Python

Let's save our data in a file and read from that file again when we re-open our app.
So let's take an example:

Let's take an example:

students =[]

def get_students_titlecase():
       students_titlecase = []
        for student in students:
           students_titlecase .append( student["name"].title())

def print_students_titlecase():
       students_titlecase = get_students_titlecase()
       print(students_titlecase)

def add_student(name,student_id=1):
        student ={"name:name", "student_id": student_id}
         students.append(student)

def save_file(student):
       try:
            f=open("students.txt","a")
            f.write(student + "\n")
             f.close()
       except Exception:
             print("Could not save")
       
def read_file():
       try:
             f=open("students.txt","r")
              for student in f.readlines():
                      add_student(student)
                f.close()
         except Exception:
              print("Could not read file")

read_file()
print_students_titlecase()

student_name=input("Enter student name: ")
student_id= input("Enter student ID: ")

add_student(student_name,student_id)
save_file(student_name)

where a= append some text
             r = reading text file

So when you run the program.the output will be something like this

Output:

Could not read file
[]
Enter student name:

Nested Functions and Closures in Python

Let's take an example:

def get_students():
      
       students=["Abhinaw","Aman"]

def get_students_titlecase():

       students_titlecase = []

       for student in students:
              students_titlecase.append(student.title())
     
        return student_titlecase

students_titlecase_names=get_students_titlecase()

print(students_titlecase_names)

This is called Nested function and basically the inner function can access the outer students So this is called closures.

Create a simple python console app

Let's create an app where user will provide the student name and Student I'd from the console.

eg: student.py

students =[]

def get_students_titlecase():
       students_titlecase = []
        for student in students:
           students_titlecase = student["name"].title()

def print_students_titlecase():
       students_titlecase = get_students_titlecase()
       print(students_titlecase)

def add_student(name,student_id=1):
        student ={"name:name", "student_id": student_id}
         students.append(student)

student_list = get_students_titlecase()

student_name=input("Enter student name: ")
student_id= input("Enter student ID: ")

add_student(student_name,student_id)
print_students_titlecase()

So in console you have to something like this and output will be

Enter student name: Abhinaw
Enter student ID:3455
Abhinaw

this is very simple Python app taking console input and also we can modify the program.

Functions Arguments in Python

            Functions Arguments

So argument is parameters where you can  provide the values to functions and also useful in case you don't have to make variable global.So let's modify our existing code for input argument.

functions.py :

students = []

def get_students_titlecase():
        student_titlecase = []
        for student in students:
                students_titlecase = student.title()
          return students_titlecase

def print_students_titlecase():
       students_titlecase = get_students_titlecase()
       print(students_titlecase)

def add_student(name) :
        students.append(name)

student_list = get_students_titlecase()

add_student("Abhinaw")

So now modify our add_student method:

def add_student(name,student_id=332)

        students.append(name)

So here you will notice student_id=332 is basically a default or optional student_id if any user does not provide student_id then it will add the value automatically but if any user provides then in that case it will be overridden by the userinput value.

Now let's add student Dictionaries to our add_student method:

def add_student(name , student_id=222)
        student = {"name:" name, "student_id", student_id}
       students.append(student)

So call this function like this

add_student(name="Abhinaw" , student_id=14)

In Python there can be multiple variable arguments such as inbuild print function.

print("hello", "World", 34, None , "Wow')

you must have question here like how come it possible let me create our own function just to cater above.

def var_args(name, *args)
        print(name)
         print(args)

just to call the function

var_args("Abhine","Android Developer",None, True)

you can add any number of argument.

There is also a concept called kwargs.
let's have a look.

def var_args(name,**kwargs):
print(name)
print(kwargs["description"],kwrgs["feedback"])

var_args("Abhinaw" ,description="Loves Android", feedback=None,androidcodingworld_subscriber=True)

it is called kwargs argument and defined with **kwrgs.So it is not a list it is Dictionaries thats where it differs from above example.

basically it was an example of variable arguments you can add as much as you can in the form of list or can also make it  Dictionaries.