Control-Flow Statements:
JSP provides full power of Java to be embedded in your web application. You can use all the APIs and building blocks of Java in your JSP programming including decision making statements, loops etc.
Decision-Making Statements:
The if...else block starts out like an ordinary Scriptlet, but the Scriptlet is closed at each line with HTML text included between Scriptlet tags.<%! int day = 3; %>
<html>
<head><title>IF...ELSE Example</title></head>
<body>
<% if (day == 1 | day == 7) { %>
<p> Today is weekend</p>
<% } else { %>
<p> Today is not weekend</p>
<% } %></body>
</html>
This would produce following result:
<head><title>IF...ELSE Example</title></head>
<body>
<% if (day == 1 | day == 7) { %>
<p> Today is weekend</p>
<% } else { %>
<p> Today is not weekend</p>
<% } %></body>
</html>
This would produce following result:
Today is not weekend
Now look at the following switch...case block which has been written a bit differentlty using out.println() and inside Scriptletas:<%! int day = 3; %>
Now look at the following switch...case block which has been written a bit differentlty using out.println() and inside Scriptletas:<%! int day = 3; %>
<html>
<head><title>SWITCH...CASE Example</title></head>
<body>
<%
switch(day) {
case 0:
out.println("It\'s Sunday.");
break;
case 1:
out.println("It\'s Monday.");
break;
case 2:
out.println("It\'s Tuesday.");
break;
case 3:
out.println("It\'s Wednesday.");
break;
case 4:
out.println("It\'s Thursday.");
break;
case 5:
out.println("It\'s Friday.");
break;
default:
out.println("It's Saturday.");
}
%>
</body>
</html>
This would produce following result:
It's Wednesday.
Loop Statements:
You can also use three basic types of looping blocks in Java: for, while,and do…while blocks in your JSP programming.Let us look at the following for loop example:<%! int fontSize; %>
<html>
<head><title>FOR LOOP Example</title></head>
<body>
<%for ( fontSize = 1; fontSize <= 3; fontSize++){ %>
<font color="green" size="<%= fontSize %>">
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</font><br />
<%}%>
</body>
</html>
This would produce following result:
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Above example can be written using while loop as follows:<%! int fontSize; %>
<head><title>FOR LOOP Example</title></head>
<body>
<%for ( fontSize = 1; fontSize <= 3; fontSize++){ %>
<font color="green" size="<%= fontSize %>">
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</font><br />
<%}%>
</body>
</html>
This would produce following result:
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Above example can be written using while loop as follows:<%! int fontSize; %>
<html>
<head><title>WHILE LOOP Example</title></head>
<body>
<%while ( fontSize <= 3){ %>
<font color="green" size="<%= fontSize %>">
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</font><br />
<%fontSize++;%>
<%}%>
</body>
</html>
This would also produce following result:
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<head><title>WHILE LOOP Example</title></head>
<body>
<%while ( fontSize <= 3){ %>
<font color="green" size="<%= fontSize %>">
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</font><br />
<%fontSize++;%>
<%}%>
</body>
</html>
This would also produce following result:
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