APEX: Adding equals and hashCode Methods to Your Class

HashCode:

Class with equal and hashCode methods:

global with sharing class AtestClass {

class TempratureReading {
        public TempratureReading(String city,Integer reading ){
            this.city = city;
            this.reading= reading;   
        }
       
        public String hashCode(){
            return this.city+this.reading;
        }
       
        public Boolean equals(Object obj) {
            TempratureReading other = (TempratureReading)obj;
            if(other.city.contains(this.city))
            return true;
            else
            return false;
           
        }
       
        String  city{get;set;}
        Integer reading{get;set;}
       
}

 List<TempratureReading>  readingsOfTheDay(){
    
     List<TempratureReading> dayReadings = new List<TempratureReading>();
     dayReadings.add(new TempratureReading('NewYork',111111111));
     dayReadings.add(new TempratureReading('Paris',222222222));
     dayReadings.add(new TempratureReading('NewYork',333333333));
     dayReadings.add(new TempratureReading('Paris',444444444));
     return dayReadings;
    
 }

public void findMaxTemp() {
   
    Map<TempratureReading,Integer> mapReading = new Map<TempratureReading,Integer>();
   
    for(TempratureReading trRec :readingsOfTheDay()){
        mapReading.put(trRec,trRec.reading);
    }
   
    for(TempratureReading trRec : mapReading.keySet()){
        System.debug( trRec.city + '   --  ' + mapReading.get(trRec));
    }
   
   
}

   
}

execute this following

AtestClass a = new AtestClass();
a.findMaxTemp();