Day 5 of 100 - Java: Functions and Objects

Working with functions

Function definition of println:

public void println(String x) {
  if(x == null) {
    x = "null";
  }
  try {
    ensureOpen();
    textOut.write(x);
  } catch (IOException e) {
    trouble = true;
  }
  newLine();
}

Function call:

System.out.println();

public - access modifier
void - return type
function() - how we call our function
inside the function - block of code

Parameters and Arguments:

public void greeting(String location) {
    System.out.println("Hello, " + location);
}

greeting("New York");

Randomly rolled dice:

/**
 * This dice function simulates a 6 sided dice roll
 *
 * @return random value from 1 to 6
 */

public int rollDice() {
    double randomNumber = Math.random(); // 0 to 0.999...
    // A dice have 1 to 6
    // i.e, so max value 6.9999 and min value of 1.00
    randomNumber = randomNumber * 6 
    // shift range up one
    randomNumber = randomNumber + 1;

   int randomInt = (int) randomNumber; // casting
   return randomInt;
}

int roll1 = rollDice(); //example, 2
int roll2 = rollDice(); //example, 4

Points on functions:

1. Easy to reuse code
2. Organize and group code
3. More maintainable code
4. Function definition is like a dictionary detail for a word in a sentence
5. Argument order is important in a function call
6. Math.Random() gives a random number between 0 and 1

Objects

Points on objects:

1. Objects combine variables together to make your code meaningful
2. Organized and maintainable code

--
https://docs.oracle.com/javase/8/docs/api/java/lang/package-summary.html