Program to check the validity of password without using regex.

Password checker program basically checks if a password is valid or not based on the password policies mention below: 

• Password should not contain any space. 
• Password should contain at least one digit(0-9). 
• Password length should be between 8 to 15 characters. 
• Password should contain at least one lowercase letter(a-z). 
• Password should contain at least one uppercase letter(A-Z). 
• Password should contain at least one special character ( @, #, %, &, !, $, etc...).

Example: 

Input: GeeksForGeeks 
Output: Invalid Password!
This input contains lowercase 
as well as uppercase letters 
but does not contain digits 
and special characters.

Input: Geek$ForGeeks7
Output: Valid Password
This input satisfies all password
policies mentioned above.

Approach:
In this program, 

• we are using String contains () method to check the passwords. This method accepts a CharSequence as an argument and returns true if the argument is present in a string otherwise returns false. 
• Firstly the length of the password has to be checked then whether it contains uppercase, lowercase, digits and special characters. 
• If all of them are present then the method isValid(String password) returns true.

Below is the implementation of the above approach: 

GeeksForGeeks - Invalid Password!
Geek$ForGeeks7 - Valid Password