Java String and Date ISYS 350

String Class Methods https://www.tutorialspoint.com/java/java_strings.htm

Testing if two strings are equal The equals() or equalsIgnoreCase method should be used to determine whether two objects have the same values. String string1 = "foo"; String string2 = "Foo"; if (string1==string2) //if (string1.equals(string2)) //if (string1.equalsIgnoreCase(string2)) { out.println("The two strings are equal."); } else out.println("The two strings are not equal.");

Split method It returns the array of strings computed by splitting this string around matches of the given character (regular expression). Example: <% String commaDelimited = "90,56,75,90,75,90,88,100"; String [] dataArray; String myStr=""; dataArray=commaDelimited.split(","); for (int i=0;i<=dataArray.length-1;i++) { myStr+=dataArray[i]; } %> <p><%=myStr%></p>

Java Date Processing: Date Class Define a date object: Date myDate; Define a date object with the current date: Date currentDate = new Date(); getTime method: return the date in milliseconds since 1/1/1900

Java Date Processing: DateFormat class DateFormat class is used to define a date format to display a date object or parsing a date/time string to create a date object. Define a date format: DateFormat formatter = new SimpleDateFormat("MM/dd/yy"); To print a data object: out.print("Current date is: " + formatter.format(currentDate)); To parse a date string: myDate=formatter.parse(request.getParameter("txtDate"));

Import Java Class Example: Display Current Date Time Import java.util.Date <%@page import="java.util.Date"%> Define a Date type variable: Date currentDate = new Date(); Display in textbox using JSP expression: <p>The time is: <input type="text" name="num2" size="20" value="<%=currentDate%>"></p>

Date to Date Format Import class: Define a format: <%@page import="java.text.DateFormat"%> Define a format: SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yy"); Convert: Example: Display a date with date format: String displayDate = formatter.format(currentDate);

Code Example <% Date currentDate = new Date(); SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yyyy"); String displayDate = formatter.format(currentDate); %> <p>The time is: <input type="text" name="num2" size="20" value="<%=currentDate%>"></p> <p>The time is: <input type="text" name="num2" size="20" value="<%=displayDate%>"></p> <p>The time is: <input type="text" name="num2" size="20" value="<%=formatter.format(currentDate)%>"></p>

Define Date Format Letter   Date or Time Component   Presentation       Examples G        Era designator              Text                AD y        Year                        Year                1996;    96 M        Month in year                Month               July; Jul; 07 w        Week in year                Number               27 W        Week in month                Number               2 D        Day in year                Number               189 d        Day in month                Number               10 F        Day of week in month        Number               2 E        Day in week                Text               Tuesday; Tue a        Am/pm marker                Text               PM H        Hour in day (0-23)        Number               0 k        Hour in day (1-24)        Number               24 K        Hour in am/pm (0-11)        Number               0 h        Hour in am/pm (1-12)        Number               12 m        Minute in hour            Number               30 s        Second in minute            Number               55 S        Millisecond                 Number               978 z        Time zone                   General time zone   Pacific Standard Time; PST; GMT-08:00 Z        Time zone                  RFC 822 time zone   -0800

Example of Date Format: Sat, April 29, 2017 SimpleDateFormat formatter = new SimpleDateFormat("E, MMMM dd, yyyy");

Calculating Days between Current Date and Entered Date Using the getTime() method <form name="dateForm" method="get" action="computeDate.jsp"> Enter a date: <input type="text" name="txtDate" value="" /><br><br> <input type="submit" value="compute Date" name="btnSubmit" /> </form>

computeDate.jsp <% Date currentDate = new Date(); Date myDate; DateFormat formatter = new SimpleDateFormat("MM/dd/yy"); myDate=formatter.parse(request.getParameter("txtDate")); out.print(currentDate +"<br>"); out.print("Current date is: " + formatter.format(currentDate)+"<br>"); out.print("Entered date is: " + formatter.format(myDate)+"<br>"); out.print ("Days between = " + (currentDate.getTime()-myDate.getTime())/(24*60*60*1000)+"<br>"); DateFormat yearFormat=new SimpleDateFormat("yyyy"); DateFormat monthFormat=new SimpleDateFormat("MM"); DateFormat weekDayFormat=new SimpleDateFormat("E"); out.print(yearFormat.format(currentDate)+"<br>"); out.print(monthFormat.format(currentDate)+"<br>"); out.print(weekDayFormat.format(currentDate)+"<br>"); %>