Retrieve Objects

public List<SelectOption> getObjectNames() {
      
        
            //Variables to hold the Obj Label and Obj LabelName map
            List<String> objLabels = new List<String>();
            Map<String, String> objLabelNameMap = new Map<String, String>();
            
            //To fetch all the objects of the current Organisation
            List<Schema.SObjectType> allObjects = Schema.getGlobalDescribe().Values();    
            List<SelectOption> objectOptions = new List<SelectOption>();
            objectOptions.add(new SelectOption('', '--None--));
            
            //Loop to iterate over all objects
            for(Schema.SObjectType objectName : allObjects) {   
            
                objLabels.add(objectName.getDescribe().getLabel());
                objLabelNameMap.put(objectName.getDescribe().getLabel(), 
                                                       objectName.getDescribe().getName());
            }
            objLabels.sort();
            for(String objLabel : objLabels){
                
                objectOptions.add(new SelectOption(objLabelNameMap.get(objLabel),objLabel));
            }
            return objectOptions;
    }
    

This will retrieve all the objects.

Retrieve fields of the selected object

public List<SelectOption> getObjectFields(String objectName) {
    
            Map<String, SObjectField> allFields = new Map<String, SObjectField>();
            
            //Fetching all the fields of the Selected Object
            allFields = allObjects.get(objectName).getDescribe().fields.getMap();  
            List<SelectOption> fieldOptions = new List<SelectOption>();
            fieldOptions.add(new SelectOption('', '--None--'));
            List<SObjectField> fieldTokens = new List<SObjectField>();
            
            //Fetching the field tokens
            fieldTokens = allFields.values();
            
            //Loop to iterate over the fieldtokens
            for(SObjectField fieldToken : fieldTokens) {
            
                DescribeFieldResult descFieldRes = fieldToken.getDescribe();
                
                fieldOptions.add(new SelectOption(descFieldRes.getName(), descFieldRes.getLabel()));
            }
            return fieldOptions;
    }

This will retrieve all the fields of the selected object.

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