package javareview;

/**
 *
 * @author Mayelin
 */
public class JavaReview1
{
    
    public static void main(String[] args) 
    {
        /****************************/
        /*         Chapter 2        */
        /****************************/
              
        // primitive data types
        double gpa_1 = 3.85;
        int gpa_2 = 2;
        boolean valid = true;
        
        
        System.out.println("The value of the gpa_1 variable is " + gpa_1);       
        System.out.println("The value of the gpa_2 variable is " + gpa_2);
        System.out.println("The value of the valid variable is " + valid + "\n");
        
        // Conversion between primitive data types: converting from a type that 
        // holds a smaller value to a type that holds a larger value happens
        // automatically.
        gpa_1 = gpa_2;
        
        // to convert the other way around, use the cast operator.
        // remember that casting a double to an int discards the fractional part
        gpa_2 = (int)gpa_1;
        
        
        // converting a String into an int
        int intValue = Integer.parseInt("5");
        
        
        
        // constant declaration
        final double MAX_GPA = 4.0;
        

        // arithmetic operators
        int result = 5 + 2;
        
        
        System.out.println("Result should be 7: " + result);

        result = result - 2;
        System.out.println("Result should be 5: " + result);

        result = result * 2;
        System.out.println("Result should be 10: " + result);

        result = result / 2;
        System.out.println("Result should be 5: " + result);

        result = result % 2;
        System.out.println("Result should be 1: " + result + "\n");

        // operator precedence: in order for the addition to be performed before the division, 
        // we need the parenthesis
        double totalGPA = (gpa_1 + gpa_2) / 2;
        
        
        // concatenation operator
        System.out.println("The value of the sum of gpa_1 + gpa_2 is " + (gpa_1 + gpa_2) + "\n");
        
      
        // unary operators
        result--;
        System.out.println("Result should be 0: " + result);
        
        result++;
        System.out.println("Result should be 1: " + result);
        
        result = -result;
        System.out.println("Result should be -1: " + result);
        
        boolean success = false;
        System.out.println("Success is true: " + !success + "\n");
        
        
        // combined assignment operators
        int temp = 4;
        temp += 6;
        System.out.println("temp should be 10: " + temp);
        
        temp /= 2;
        System.out.println("temp should be 5: " + temp);
        
        temp %= 2;
        System.out.println("temp should be 1: " + temp);
        
        
        // using the increment/decrement operators in prefix and postfix form    
        int i = 3;
        i++;
        System.out.println("This prints 4: " + i);
        
        ++i;			   
        System.out.println("This prints 5: " + i);
        
        System.out.println("This prints 6: " + ++i);
        
        System.out.println("This prints 6: " + i++);
        
        System.out.println("This prints 7: " + i + "\n");
        
   
        // String class
        String name = "John Smith";
        System.out.println("The character at position 2 is: " + name.charAt(2));
        System.out.println("Does name contain the sequence \"hn\"? " + name.contains("hn"));
        System.out.println("A 4 character substring of name is: " + name.substring(6));
        System.out.println("She said: \"See you ma\u00F1ana\"");
        
        
        /****************************/
        /*         Chapter 3        */
        /****************************/
        
        // if statement
        double salary = 30000.50;
        int yearsOnJob = 3;
        
        if( salary >= 20000 )
        {
            if( yearsOnJob >= 2 )
                System.out.println("You qualify for the loan.\n");
            else
                System.out.println("You must have been on your current job for at least 2 years.\n");
        }
        else
        {
            System.out.println("You must earn at least $20,000.00 per year to qualify for a loan.\n");
        }
        
        
        // if-else-if statement
        int testScore = 75;

        if (testScore < 60)
            System.out.println("Your grade is F.\n");
        else if (testScore < 70)
            System.out.println("Your grade is D.\n");
        else if (testScore < 80)
            System.out.println("Your grade is C.\n");
        else if (testScore < 90)
            System.out.println("Your grade is B.\n");
        else
            System.out.println("Your grade is A.\n");
      
      
        // logical operators
        int x = 25;
        int y = 2;
        
        if ((x >= 0 && x <= 10) || (y >= 5 && y <= 15)) 
        {
            System.out.println("The first check is true\n");
        }
        else 
        {
            if ((x >= 11 && x <= 20) || (y >= 16 && y <= 25)) 
            {
                System.out.println("The second check is true\n");
            } 
            else 
            {
                System.out.println("Both checks are false\n");
            }
        }
        
        
        // syntax for the conditional operator - also called ternary operator:
        // result = testCondition ? value1 : value2;
        y = (x >= 0) ? x : -x; 
        
        // is equivalent to:
        if (x >= 0) 
            y = x; 
        else 
            y = -x; 

        
        // switch statement
        int number = 3;
        switch (number) 
        {
            case 1:
                    System.out.println("The number is 1");
                    break;
            case 2:
                    System.out.println("The number is 2");
                    break;
            case 3:
                    System.out.println("The number is 3");
                    break;
            case 4:
                    System.out.println("The number is 4");
                    break;
            case 5:
                    System.out.println("The number is 5");
                    break;
            default:
                    System.out.println("The number is not 1, 2, 3, 4, or 5");
        }

        
        // using the printf method to format output
        double currency = 2454645.125478;
        int myIntValue = 564654554;
        // - left justify
        // , include comma separator
        // 12 width
        // .2 precision points
        // f floating-point number
        // d integer
        System.out.printf("The amount is: $%-,12.2f\n", currency);
        System.out.printf("The amount is: $%-,12d\n\n", myIntValue);
        
        // using the format method in the String class to format output
        String formattedString = String.format("The amount is: $%-,12.2f\n", currency);
        System.out.println(formattedString);

    }

}