Extra-Strength Methods — Chapter 5

Developing a class includes few steps

1. Figure out what the class is supposed to do.
2. List the instance variables and methods.
3. Write prep code for the methods.
4. Write test code for the methods.
5. Implement the class (real code).
6. Test the methods
7. Debug and reimplement as needed

Extreme Programming (XP)

• It is a newcomer to the software development methodology.
• Emerged in the late 90’s
• Adopted by many companies.
• It helps with quick adaptation.
• It is based on a set of proven practices that are all designed to work together.
• Some adopt only a portion of XP’s rules

Rules of XP

• Small but frequent releases
• Develop in iteration cycles
• No additions than the spec
• Write the test code first
• No killer schedules
• Work regular hours
• Refactor (improve the code) whenever and wherever you notice the opportunity.
• Don’t release anything until it passes all the tests.
• Set realistic schedules, based around small releases.
• Keep it simple.
• Program in pairs
• Move people around so that everybody knows pretty much everything.

Post-increments vs Pre-increments in Java

++a increments and then uses the variable.
a++ uses and then increments the variable.

Example 1

a = 1;
System.out.println(a++); //You will see 1
//Now a is 2
System.out.println(++a); //You will see 3

Example 2

int x = 5, y = 5;

System.out.println(++x); // outputs 6
System.out.println(x); // outputs 6

System.out.println(y++); // outputs 5
System.out.println(y); // outputs 6

Example 3

This only matters when the ++x is part of some larger expression rather than just in a single statement.

int x = 0 ;

int z = ++x; //produces: x is 1, z is 1

But putting the ++ after the x give you a different result:

int x = 0;

int z = x++; //produces: x is 1, but z is 0

Casting

If the value of y was bigger then the maximum value of x, then what’s left will be a weird (but calculable) number that is assigned to x.

long y == 40002; //40002 exceeds the 16-bit limit of a short

short x =(short) y; //x now equals -25534! (short’s range is -32,768 to 32,767 (inclusive) so the value goes in a round when limit is exceeded)

Note

• Integer.parselntO works only on Strings that represent the ASCII values for digits (0,1,2,3,4,5,6,7,8,9). Any other input will throw an exception.
• If you want a random number between 0 and 4 use,

int randomNum = (int) (Math.random() * 5);

• Multiple initializations and iteration expressions can be done on a for loop.

Thanks for reading. Until next time! 👋🏽