1. Java String and Date
ISYS 350

2. String Class Methods

3. 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.");

4. 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>

5. 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

6. 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"));

7. Import Java Class Example: Display Current Date Time
Import java.util.Date
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>

8. Date to Date Format Import class: Define a format:
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);

9. 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>

10. 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

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

12. 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>

13. 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>");
%>