Iterator and Iterable issue - must implement the method: System.Iterable<SObject> Database.Batchable<SObject>.start(Database.BatchableContext)

Question

Unlike OP in this question, I am using a custom iterator and I'm getting the same error as stated in the title.

This is my first attempt of writing a custom iterator and I'm having troubles compiling the code, please bear with me.

My goal is to pass a list of strings to a batch, and process each one individually.

This is what I have so far:

My Class

String a ='test';
string b = 'test2';
List<String> jsonStrings;
jsonStrings.add(a);
jsonStrings.add(b);
Database.executeBatch(new CustomBatch(jsonStrings),1);

CustomBatch

global class CustomBatch implements Database.batchable<SObject>{ 

   global Iterable<String> start(Database.batchableContext info,List<SObject> jsonStrings){ 
       return new CustomIterable(jsonStrings); 
   }     
   global void execute(Database.batchableContext info, List<String> scope){ 
       List<String> jsonsToUpdate = new List<String>(); 
       Integer i = 0;
       for(String a : scope){ 
           System.debug(loggingLevel.Error, '*** json_'+i+': '+ + a); 
           i++;
       } 
   }     
   global void finish(Database.batchableContext info){     
   } 
}

CustomIterable:

global class CustomIterable implements Iterable<String>,Iterator<String>{ 

   List<String> jsons {get; set;} 
   Integer i {get; set;} 
   public Iterator<String> iterator() { return this; }

   public CustomIterable(List<String> jsonStrings){ 
       jsons=jsonStrings; 
       i=0;
   }   

   global boolean hasNext(){ 
       if(i >= jsons.size()) {
           return false; 
       } else {
           return true; 
       }
   }    

   global String next(){ 
       i++; 
       return jsons[i-1]; 
   } 
}

Errors while trying to save CustomBatch:

Result: [OPERATION FAILED]: classes/CustomBatch.cls: Class CustomBatch must implement the method: System.Iterable Database.Batchable.start(Database.BatchableContext) (Line: 1, Column: 14)

classes/CustomBatch.cls: Class CustomBatch must implement the method: void Database.Batchable.execute(Database.BatchableContext, List) (Line: 1, Column: 14)

Answer 1

Note that List<String> implements Iterable<String> so you don't have to write a class for that.

Something like this is closer to what you are looking for:

public class CustomBatch implements Database.Batchable<String> {

   private List<String> jsonStrings;

   public CustomBatch(List<String> jsonStrings) {
       this.jsonStrings = jsonStrings;
   }

   public List<String> start(Database.BatchableContext info) { 
       return jsonStrings; 
   }

   public void execute(Database.BatchableContext info, List<String> scope) { 
       Integer i = 0;
       for(String a : scope){ 
           System.debug(loggingLevel.Error, '*** json_' + i + ': ' + a); 
           i++;
       } 
   }

   public void finish(Database.BatchableContext info) {     
   } 
}