DataTypes Answers & Notes.java

@isTest
public class DataTypeTestAnswers {
    public static TestMethod void DataTypes(){
        
        string text1 = 'this text';
        string text2 = 'that text';
        
        string text3 = text1 + text2;
        System.debug(text3);
        text3 = text3 + 'more text';
        System.debug(text3);
        
        string text4 = text3.toUpperCase();
        System.debug('SHOUT! ' + text4);
        
        /* For practicing dot notation and method usage 
         */
        string text5 = text4.toLowerCase();//FIX ME!!! Turn text4 into a lower case string.
        System.debug('whisper ' + text5);
        
        /* For practicing dot notation and method research.
         * Other possible solutions (e.g. replace(' ', '')) 
         */
        string text6 = text5.deleteWhitespace();//FIX ME!!! Find a string method to remove whitespaces.
        System.debug('No more whitespaces: ' + text6);
        
        /* For practicing debug statements
         * Demos methods with arguments and escape character
         */
        string text7 = text6.remove('text');
        System.debug('This is what\'s left: ' + text7);//FIX ME!!! Edit the debug output to include text7.
        
        /* Demos mutliple arguments
         */
        string text8 = text7.replace('more', 'less');
        System.debug('now with less! ' + text8);
        
        /* Demos integer argument
         */
        string text9 = text8.repeat(2);
        System.debug('repeated twice: ' + text9);
        
        /* Demos return values of different data types
         * Introduce Integer DataType
         */
        Integer number1 = text9.length();
        System.debug('how long? ' + number1);
        
        /* Introduces concept of Index
         */
        Integer number2 = text9.indexOf('this');
        System.debug('find this: ' + number2);
        
        /* For practicing use of Index
         */
        Integer number3 = text9.indexOf('that');//FIX ME!!! Use indexOf() to find 'that' in text9.
        System.debug('find that: ' + number3);
        
        /* Introduces System.assertEquals
         * Demonstrates determining index values to use as Expected value in assertEquals
         */
        Integer number4 = text9.LastIndexOf('that');
        System.assertEquals(16, number4, 'Expected value should equal actual value returned by lastIndexOf()');
        
        /* Practice determining index value
         */
        Integer number5 = text9.IndexOf('less');//FIX ME!!! Can you guess what the index of 'less' will be?
        System.assertEquals(null,null);
        
        //define some numbers we'll use to work with Integers and operators
        Integer number6 = 6;
        
        Integer number7 = 7;
        
        /* Introduces math operators + and ++
         * Explores how ++ before or after an Integer behaves differently
         */
        Integer sum1 = number6 + number7;
        System.Debug('do the math: ' + sum1);
        System.Debug('x++ returns value then increments: ' + sum1++);
        System.Debug('what is the value now?: ' + sum1);
        System.Debug('++x increments then returns value: ' + ++sum1); 
        System.assertEquals(15, sum1);
        
        /* Practice using math operators + and ++
         * Practice using assertEquals
         */
        Integer sum2 = number7 + number6;//FIX ME!!! add number7 to number6
        Integer sum3 = ++sum2;//FIX ME!!! set sum3 to increment sum2.
        System.assertEquals(14, sum3);//FIX ME!!! Uncomment and add your expected result.
        
        /* Explore difference between Integers and Decimals in Apex
         * by demonstrating that Apex does not reinterpret data types:
         * dividing two integers produces another integers
         * and drops the decimal remainder regardless of whether the result
         * is assigned to a decimal or integer.
         */
        //What happens if we assign a non-integer value?
        Integer decimal0 = number6 / number7;
        System.debug('Integer of 2 integers divided: ' + decimal0);
        
        //Even though the result is a decimal, 2 Integers divided are still treated as integers.
        Decimal decimal1 = number6 / number7;
        System.debug('Decimal of 2 integers divided: ' + decimal1);
        
        /* Introduces casting as a quick means of converting datatypes
         */
        //"Casting" is a useful technique to convert one data type to another.
        Decimal decimal2 = (decimal)number6 / (decimal)number7;
        System.debug('2 integers "cast" to decimals: ' + decimal2);
        
        /* Introduces Double and Long numeric types
         * Introduces definining decimals or longs without casting
         */
        //Care must be taken when working with different numeric types:
        //Explicitly declare Double or Decimal values by adding .0 if no fractional value is present
        Double nope = 5/3;
        System.debug('Double of divided integers: 5/3 != ' + nope);
        Double better = 5.0/3.0;
        System.debug('Double of divided integers with .0 added: 5.0/3.0 == ' + better);
        //Explicitly declare Long values by adding L if the number is likely to exceed 2147483647
        Long wrong = 2147483647 + 1;
        System.debug('Maximum integer value of 2147483647 plus 1: ' + wrong);
        Long right = 2147483647L + 1;
        System.debug('Maximum integer value as a Long plus 1: ' + right);
        
        /* Introduces Date, Datetime and Time datatypes
         */
        //Dates and times are both tricky and easy to work with.
        Date date1 = Date.today();
        Datetime datetime1 = Datetime.now();
        Time time1 = Time.newInstance(18, 30, 2, 20);
        
        /* Demonstrates chained dot notation
         */
        Time time2 = Datetime.now().time();
        
        /* Demonstrates mathematical operations with dates
         */
        Date date2 = date1 + 1;
        System.debug('Tomorrow: ' + date2);
        
        /* Practice date calculation
         * Practice creating the entire data type declaration, variable name & value
         */
        Date date3 = date2 - 2;
        System.debug('Yesterday: ' + date3);//FIX ME!!!

    }
}