working.md

ASCII // character codes

American Standard Code for Information Interchange, is a character encoding standard for electronic communication.

Type Casting

The simplest way to convert a floating-point value to an integer is to use a type cast, so called because it molds or “casts” a value from one type to another. The syntax for type casting is to put the name of the type in parentheses and use it as an operator.

double pi = 3.14159;
int x = (int) pi;
System.out.println(x)
// 3

Converting to an integer it simply throws away the fractional part.

type cast: An operation that explicitly converts one data type into another. In Java it appears as a type name in parentheses, like (int).

Java Final Modifier

Want a variable to never be capable of being changed? Java provides a language feature that enforces that rule, the keyword final.

Declaring that a variable is final means that it cannot be reassigned once it has been initialized. If you try, the compiler reports an error. Variables declared as final are called constants.

By convention, names for constants are all uppercase, with the underscore character (_) between words.

• final primitive variables can be set only once (constant)
  • final double cmPerInch = 2.54;
• final object variables may be modified, final applies to object reference.
• final fields can be set only once (constant)
• final methods can’t be overridden, hidden
• final classes can't be extended

More on Objects

Objects and methods Use standard Object methods: equals(), toString(), compareTo()

Java's API documentation to select and use appropriate classes, objects, constructors, and methods.

Input and Output

Testing

@Test
public void testAddNumbers() {
    int x  = 1 ; int y = 1;
    assertEquals(2, Calculator.addNumbers(x,y));
}

@Test
public void testSubtractNumbers() {
    int x  = 1 ; int y = 1;
    assertEquals(0, Calculator.subtractNumbers(x,y));
}

public class Calculator {
    public static void main(String[] args) {
        System.out.println(addNumbers(400, 20));
        System.out.println(addNumbers(60, 9));
    }

    public static int addNumbers(int x, int y) {
        return x + y;
    }

    public static int subtractNumbers(int x, int y) {
        return x + y;
    }
}

Conditionals

Loops

Algorithms

Common Array Algorithms

counting, adding, computing the min/max

Search Algorithms

Linear search, non-recursive binary search, and non-recursive sorting algorithms (e.g. bubble sort, selection sort, insertion sort)

Compare algorithms with respect to their efficiency, elegance, and readability