CODEWITHSUNDEEP
javakotlinarraylistkey-value
Aswin S Kumar
Aswin S Kumar

Reputation: 3

Changing value of specific key changes the value of other keys as well

This is how I generate dutyList.

val dutyList = ArrayList<Triple<Int, String, ArrayList<Pair<String, String>>>>()

val dateShiftPair = ArrayList<Pair<String, String>>()

dateList.forEach {date ->
     dateShiftPair.add(Pair(date, "E"))
}


staffList.forEach {staff -> 
     dutyList.add(Triple(list.indexOf(staff), staff.name!!, dateShiftPair))
}

And this should change the second value of the pair

override fun onShiftChange(pos: Int, datePos: Int, shift: String) {
        val pair = Pair(staffList[pos].third[datePos].first, shift)
        staffListUpdated[pos].third[datePos] = pair
    }

but instead it changes other values in pos, that is if I change staffListUpdated[0].third[0] = pair it changes staffListUpdated[1].third[0] = pair as well. I tried many ways but nothing helped.

[
  {
    "first": 0,
    "second": "Ralph",
    "third": [
      {
        "first": "3/5",
        "second": "G" //change should happen here only
      },
      {
        "first": "4/5",
        "second": "E"
      },
      {
        "first": "6/5",
        "second": "E"
      }
    ]
  },
  {
    "first": 1,
    "second": "Mike",
    "third": [
      {
        "first": "3/5",
        "second": "G" //but change happens here as well.
      },
      {
        "first": "4/5",
        "second": "E"
      },
      {
        "first": "5/5",
        "second": "E"
      }
    ]
  }
]

Upvotes: 0

Views: 232

Answers (1)

Ackdari
Ackdari

Reputation: 3508

In

staffList.forEach {staff -> 
     dutyList.add(Triple(list.indexOf(staff), staff.name!!, dateShiftPair))
}

you use for every Triple the same list instance.

This means if you get the list of one of your Triples and change something you change it for every Triple.

A solution is to copy the list either on insertion or on modification.

You also need to do a deep copy of the list. Because if you make a shallow copy of the list the instances of the Pairs are still the same and if you then change one of them you change it (again) for every Triple.

Upvotes: 1

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