Collection
When we want to save multiple data of “the same type” and also connect with each other with some “common business rule”, then instead of creating multiple variables, we need to create one variable of type collection.
The same type = all the data are integers or all are strings.
Common business rule = For eg age of all employees or the salary of all employees.
“Collections are same like an array” - We have 3 types of collections in Salesforce, and they are:
- List.
- Set.
- Map.
- List
- Collection - List
- Sample program for List
- Program#1 - How to add values to the list?
- Program#2 - How to get values from positions?
- Program#3 - How to set a value at certain position?
- Program#4 - How to clear all the values?
- Program#5 - How to remove one value instead of all values?
- Program#6 - How to get the particular value size?
List
The list has a collection of ordered elements. It means, each and every element’s place is fixed or we can tell where an element will be, by using index number.
Collection - List
- The list is an ordered collection of elements that are distinguished by indices.
- The index position of the first element in the list is always zero.
- It can store primitive data types (integer, string), SObjects.
- It can have duplicate values.
Syntax;
List MyList = New List (); List MyList = New List ();
Sample program for List
Scenario: Add salaries of employees in the list and process them with step by step execution with collection functions The below mentioned are 6 individual programs for adding the salary of the employees via List.
Program#1 - How to add values to the list?
Code:
// declare a list variable List EmpSalList = New List (); //add values to the list EmpSalList.add(10000); EmpSalList.add(20000); EmpSalList.add(30000); EmpSalList.add(40000); //values system.debug('The Current Salary = ' + EmpSalList);
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OutPut:
17:21:11:002 USER_DEBUG [12]|DEBUG|The Current Salary = (10000, 20000, 30000, 40000
Program#2 - How to get values from positions?
Code:
// declare a list variable List EmpSalList = New List (); //add values to the list EmpSalList.add(10000); EmpSalList.add(20000); EmpSalList.add(30000); EmpSalList.add(40000); //get values from position Integer TempEmpSal = EmpSalList.get(0); system.debug('The value for 0 is = ' + TempEmpSal);
OutPut:
17:21:11:002 USER_DEBUG [12]|DEBUG|The set value for 0 is =10000
Program#3 - How to set a value at a certain position?
Code:
// declare a list variable List EmpSalList = New List (); //add values to the list EmpSalList.add(10000); EmpSalList.add(20000); EmpSalList.add(30000); EmpSalList.add(40000); //set value for certain position EmpSalList.set(0, 50000); system.debug('The set value for 0 is =' + EmpSalList);
OutPut:
17:58:05:002 USER_DEBUG [15]|DEBUG|The set value for 0 is =(50000, 20000, 30000, 40000)
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Program#4 - How to clear all the values?
Code:
// declare a list variable List EmpSalList = New List (); //add values to the list EmpSalList.add(10000); EmpSalList.add(20000); EmpSalList.add(30000); EmpSalList.add(40000); //get values from position Integer TempEmpSal = EmpSalList.get(0); system.debug('The value for 0 is = ' + TempEmpSal); //set value for certain position EmpSalList.set(0, 50000); system.debug('The set value for 0 is =' + EmpSalList); //To clear all values EmpSalList.clear(); system.debug('The values =' + EmpSalList);
OutPut:
18:03:12:002 USER_DEBUG [12]|DEBUG|The value for 0 is = 10000 18:03:12:002 USER_DEBUG [16]|DEBUG|The set value for 0 is =(50000, 20000, 30000, 40000) 18:03:12:002 USER_DEBUG [20]|DEBUG|The values =()
Program#5 - How to remove one value instead of all values?
Code:
// declare a list variable List EmpSalList = New List (); //add values to the list EmpSalList.add(10000); EmpSalList.add(20000); EmpSalList.add(30000); EmpSalList.add(40000); //get values from position Integer TempEmpSal = EmpSalList.get(0); system.debug('The value for 0 is = ' + TempEmpSal); //set value for certain position EmpSalList.set(0, 50000); system.debug('The set value for 0 is =' + EmpSalList); //To clear all values EmpSalList.remove(0); system.debug('The values =' + EmpSalList);
OutPut:
18:09:51:022 USER_DEBUG [12]|DEBUG|The value for 0 is = 10000 18:09:51:022 USER_DEBUG [16]|DEBUG|The set value for 0 is =(50000, 20000, 30000, 40000) 18:09:51:022 USER_DEBUG [20]|DEBUG|The values =(20000, 30000, 40000)
Program#6 - How to get a particular value size?
Code:
// declare a list variable List EmpSalList = New List (); //add values to the list EmpSalList.add(10000); EmpSalList.add(20000); EmpSalList.add(30000); EmpSalList.add(40000); //get values from position Integer TempEmpSal = EmpSalList.get(0); system.debug('The value for 0 is = ' + TempEmpSal); //set value for certain position EmpSalList.set(0, 50000); system.debug('The set value for 0 is =' + EmpSalList); //To clear all values EmpSalList.remove(0); system.debug('The values =' + EmpSalList); //length of the value Integer length = EmpSalList.size(1); system.debug(‘The Size of 1 is ’ + length);
OutPut:
18:25:32:002 USER_DEBUG [12]|DEBUG|The value for 0 is = 10000 18:25:32:002 USER_DEBUG [16]|DEBUG|The set value for 0 is =(50000, 20000, 30000, 40000) 18:25:32:002 USER_DEBUG [24]|DEBUG|The Size of 1 is 3.
Assignment: Create a list of 10 employees, Salaries. Print their salaries one by one 10 times using system.debug().
Hint: List + for each loop.
In the next topic, we will discuss in detail about “Salesforce Collection - Set”. Keep following us for more info on Salesforce Development / Programming.
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