if-else conditional block in visualforce - salesforce

Question

I had used c:if, c:when JSTL tags in jsp. But I don't know if anything similar is available for visual force pages. just for example I am providing sample code for jsp. --
<h1>A Demo conditional section code</h1>
<c:choose>
<c:when test="${param.colorField == 'red'}">
<table border="0" width="150" height="50" bgcolor="#ff0000">
<tr><td>It is red</td></tr>
</table>
</c:when>
<c:when test="${param.colorField == 'blue'}">
<table border="0" width="150" height="50" bgcolor="#0000ff">
<tr><td>It is blue</td></tr>
</table>
</c:when>
<c:when test="${param.colorField == 'green'}">
<table border="0" width="150" height="50" bgcolor="#00ff00">
<tr><td>Green table</td></tr>
</table>
</c:when>
<c:otherwise>
<table border="0" width="150" height="50" bgcolor="#000000">
<tr><td>No colour changed</td></tr>
</table>
</c:otherwise>
</c:choose>
<br/>
and other codes....
I am missing this kind of page block preparation in vf pages.

Answer 1

What I have found that we can use outputpanel (<apex:outputpanel>) for any block and use the rendered attribute to handle the condition for loading it.
<h1>A Demo conditional section code</h1>
<apex:outputpanel rendered="{!param.colorField == 'red'}">
<table border="0" width="150" height="50" bgcolor="#ff0000">
<tr><td>It is red</td></tr>
</table>
</apex:outputpanel>
<apex:outputpanel rendered="{!param.colorField == 'blue'}">
<table border="0" width="150" height="50" bgcolor="#0000ff">
<tr><td>It is blue</td></tr>
</table>
</apex:outputpanel>
:
:
and other codes....

Answer 2

Same concept as the other answers on here, but you can use the rendered attribute on a PageBlock to render that block or not:
<apex:pageBlock rendered="{!object.Color == 'red'}">
it is red
</apex:pageBlock>
<apex:pageBlock rendered="{!object.Color == 'blue'}">
it is blue
</apex:pageBlock>
<apex:pageBlock rendered="{!object.Color == 'green'}">
it is green
</apex:pageBlock>

Answer 3

In visualforce you can use some logical operators and functions.
Explanation here
You need "Logical Functions" list, same code that you provide, in VF must look like this:
{!IF(salary<=0, "Salary is very low to survive.", "No comment sir")}

Answer 4

You need to put the logic in the controller (where most people say it belongs anyways). Your VF would look like:
<table border="0" width="150" height="50" bgcolor="{!bgColorVar}">
And in your controller, define your logic in the getter:
public string bgColorVar{
get{
//logic
}
set;
}