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pooja chauchan Calculations on a list
Hello everyone,
I am trying to do some data manipulation over records in a list. I was able to correctly build my list but now I am stuck with the calculations that I want to see happen.
Let's say I have record 1 and record 2 in my list. I want to grab a field called meter readings on both record and subtract the value of record 2 from the value from record 1 to get the actual energy use.
record 1 energy use = record 1 meter reading - record 2 meter reading.
And obvisouly I would like to repeat that for every records in my list except for the last one (since I would not have a second meter reading to do the calculation).
At first I thought of using a variable to control the for loop but I keep getting the following error message: "System.ListException: List index out of bounds: 15"
I am trying to do some data manipulation over records in a list. I was able to correctly build my list but now I am stuck with the calculations that I want to see happen.
Let's say I have record 1 and record 2 in my list. I want to grab a field called meter readings on both record and subtract the value of record 2 from the value from record 1 to get the actual energy use.
record 1 energy use = record 1 meter reading - record 2 meter reading.
And obvisouly I would like to repeat that for every records in my list except for the last one (since I would not have a second meter reading to do the calculation).
At first I thought of using a variable to control the for loop but I keep getting the following error message: "System.ListException: List index out of bounds: 15"
List<Item__c> currentItemList = meterToItemMap.get(currentMeter); if(currentItemList ! = null && currentItemList.size()>) { For( Integer i =0; i <currentItemList.size(); i++) { Integer x = i+1; if(currentItemList.size()> x){ currentItemList[i].Item_Use__c =(currentItemList[i].Meter_readings__c - currentItemList[x].meter_readings__c)*currentItemList[i].Meter_Multiplier__c; } }All Answers
List<Item__c> currentItemList = meterToItemMap.get(currentMeter); if(currentItemList ! = null && currentItemList.size()>) { For( Integer i =0; i <currentItemList.size(); i++) { Integer x = i+1; if(currentItemList.size()> x){ currentItemList[i].Item_Use__c =(currentItemList[i].Meter_readings__c - currentItemList[x].meter_readings__c)*currentItemList[i].Meter_Multiplier__c; } }Meter__c[] readings = [SELECT Id, Reading__c, Reading_Date__c FROM Meter__c WHERE Account__c = 'Some_Assumed_Parent_Record' ORDER BY Reading_Date__c ASC]; Integer finalReading = readings[0].Reading__c; //Get initiall reading for( Integer x =1; x<readings.size(); x++){ //Since we already for the first reading to set as the default, we can skip item 0 finalReading -= readings[x].Reading__c; } /* The above is a basic example, if you need to do multiple readings, it would look something like this */ public class MeterWrapper { Meter__c[] readings {get;set;} Integer finalReading {get;set;} public MeterWrapper(Meter__c[] readings){ this.readings = readings; } public void calculateReading(){ this.finalReading = readings[0].Reading__c; //Get initiall reading for( Integer x =1; x<readings.size(); x++){ //Since we already for the first reading to set as the default, we can skip item 0 this.finalReading -= readings[x].Reading__c; } } } // The above lets you put the MeterWrappers in a map.. I.e.. Map<Id, MeterWrapper> Where the Id is an AccountIdI think this should cover a few scenarios for you, but keep in mind that the code is untested and may require some tweaking (especially since I used made up custom objects to fit the scenario).