Apex outputtext value attribute

Question

This is a generic question

apex:outputText value="{**0**,date,MM'/'dd'/'yyyy}"

What I wanted to know is what is the 0 in value used for?

Answer 1

Here, 0 tells you which argument index to merge in. So usually, you just have one argument, and merging it in uses the 0-index parameter. But you might for some reason have multiple arguments (each represented by an <apex:param>).

<apex:outputText value="{0} {1, date, MM}">
    <apex:param value="test" />
    <apex:param value="{!NOW()}" />
</apex:outputText>

As represented by the above example, you can merge multiple arguments into one format string. It is very similar behavior to the String.format method in Apex, though I don't believe you can do date formatting that way.

Answer 2

The value attribute on "apex:outputText" is a valid format. It must be a positive number, and of type Number, Date, Time, or Choice.

For more info please check this url

https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_compref_outputText.htm?search_text=apex:outputtext

As per String.formate in Java and apex you can say.....

under documented Apex String API i.e.

String formattedString = String.format(String template, List<String> arguments)

String.format(..) is again based on Java MessageFormat class, its documentation says :

Treat the current string as a pattern that should be used for substitution in the same manner as apex:outputText.

Nice part of this String API is that it supports basic text substitution for ex.

// Create a Template String, that has tokens of form {index} 

String templateString = 'Hello {0}, Good to see you in {1}';

// String argument list or array matching each {index} in Template String.

String[] arguments = new String[] {'Ram' , 'India'};

// Call String.format() to get the token replaced

String formattedString = String.format(templateString, arguments);

System.debug(formattedString);

// output : Hello Ram, Good to see you in India

Bad part about this String API is it only supports String arguments for token replacement. Though both Java’s MessageFormat and Visuaforce apex:outputText tag accept non-string arguments like Date, Datetime & Currency and are capable of doing very smart formatting with them. For ex. in visualforce one can format date using outputText as follows.

<apex:outputText value="The formatted time right now is: 
    {0,date,yyyy.MM.dd G 'at' HH:mm:ss z}">
   <apex:param value="{!NOW()}" />
</apex:outputText>

output: The formatted time right now is: 2004.11.20 AD at 23:49:02 GMT

Similar Java example with more options would be

Object[] arguments = {

 new Integer(7),

 new Date(System.currentTimeMillis()),

 "a disturbance in the Force"

};

String result = MessageFormat.format(

 "At {1,time} on {1,date}, there was {2} on planet {0,number,integer}.",

 arguments);

output: At 12:30 PM on Jul 3, 2053, there was a disturbance

       in the Force on planet 7.

Sadly, if you try to do something similar with Apex it always fails for StringException.