public class LeadClass{


private Lead leadToConvert = null;
public LeadClass(){
//Lead myLead = new Lead(LastName = 'Fry', Company='Fry And Sons');

//insert myLead;
String leadId = System.currentPageReference().getParameters().get('leadId');
leadToConvert = [SELECT Id,Phone, Company
                                 FROM Lead WHERE Id = :leadId];


Database.LeadConvert lc = new database.LeadConvert();

lc.setLeadId(leadToConvert.id);



LeadStatus convertStatus = [SELECT Id, MasterLabel FROM LeadStatus WHERE IsConverted=true LIMIT 1];

lc.setConvertedStatus(convertStatus.MasterLabel);



Database.LeadConvertResult lcr = Database.convertLead(lc);

System.assert(lcr.isSuccess());
}
 
}



==============
<apex:page controller="LeadClass">

</apex:page>




======================
https://developer.salesforce.com/forums/?id=906F0000000MIzZIAW__Trigger and test

https://developer.salesforce.com/forums/?id=906F00000008zJVIAY---trigger and test2

http://stackoverflow.com/questions/30092286/lead-conversion-in-salesforce-using-apex

https://developer.salesforce.com/forums/?id=906F0000000AdlYIAS---good example

https://developer.salesforce.com/forums/?id=906F00000008xTWIAY-----with simple example

http://salesforce.stackexchange.com/questions/4756/convert-lead-through-apex-but-should-not-create-opportunity
====
==https://developer.salesforce.com/forums/?id=906F00000008xTWIAY



apex/LeadConversion?leadId={!Lead.Id}'

https://c.ap2.visual.force.com/apex/ld?leadId='00Q2800000LVmZh'