Show List of Arrays in an ArrayList in Android

Question

I am trying to create a list of arraylist in android. Here is my expected formate.

  [[90.35911560058594, 23.762723181676783],
  [90.36435127258301, 23.764608467290504],
  [90.36520957946776, 23.764922678903957],
  [90.36606788635254, 23.76327305946888],
  [90.36941528320312, 23.763901488386157],
  [90.3706169128418, 23.76445136119925],
  [90.36735534667969, 23.772070788117777],
  [90.3665828704834, 23.77324901017239],
  [90.3614330291748, 23.773327557929896],
  [90.35877227783203, 23.76979286188437],
  [90.35911560058594, 23.76979286188437]]

I used two lists List<Double> nodes = new ArrayList<>() and List<List<Double>> list = new ArrayList<List<Double>>(). Then I added the followings

                nodes.add(latLng.longitude);
                nodes.add(latLng.latitude);
                list.add(nodes);

But this is showing the following output,

Coordinate_List: [81.5364906191826, 56.07605883895308, 86.5351914614439, 61.56546071581482, 94.52162001281975, 59.151354552315375]

All elements are showing in one arraylist. But I need to show this one -

[[90.35911560058594, 23.762723181676783],
      [90.36435127258301, 23.764608467290504]]

Can anyone please suggest me possible ways to do this?

What is showing "the following output"? Which code renders this output? — Rolf ツ
– Rolf ツ, Commented Jan 2, 2017 at 8:17
are you creating a new nodes arraylist for each pair of co-ordinates? — Suraj Rao
– Suraj Rao, Commented Jan 2, 2017 at 8:18

Lalit Jadav · Accepted Answer · 2017-01-02 10:12:57Z

2

It is good if you create model class for latlng.

public class LatLngSinglton{
   private double mylat;
   private double mylng;
}

then assign these values in singlton class

ArrayList<LatLngSinglton> myLatlongs = new ArrayList<>();
myLatlongs.add(new LatLngSinglton(lat, lng));

This way you can get your expected format.

edited Jan 2, 2017 at 10:12

answered Jan 2, 2017 at 8:21

Lalit Jadav

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2 Comments

patrik Over a year ago

What does singleton class mean here? I assume that you do not mean your program to have one single instance of LatLngSinglton?

Lalit Jadav Over a year ago

LatLngSinglton class is just model class.

guest · Accepted Answer · 2017-01-02 08:36:50Z

1

Could you post more of your code? And are you creating a new list for every coordinate? It Looks a bit like you are adding all your coordinates to the same list.

Maybe this minimal example can help you:

public class Main {
    public static void main(String[] args) {
        List<List<Double>> list = new ArrayList<List<Double>>();
        add(list, 10.5, 12.87);
        add(list, 20.5, 22.87);
        add(list, 30.5, 32.87);
        System.out.println(list);
    }

    private static void add(List<List<Double>> list, double lat, double lon) {
        List<Double> nodes = new ArrayList<Double>();
        nodes.add(lat);
        nodes.add(lon);
        list.add(nodes);
    }
}

output:

[[10.5, 12.87], [20.5, 22.87], [30.5, 32.87]]

answered Jan 2, 2017 at 8:36

guest

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1 Comment

Andreas Over a year ago

The add() method could be implemented simply as list.add(Arrays.asList(lat, lon)). The fact that Arrays.asList() returns a fixed-size list should not be an issue here.

ρяσѕρєя K · Accepted Answer · 2017-01-02 08:20:54Z

0

Instead of using List<Double> nodes, use JSONArray to store longitude and latitude then added it to list :

JSONArray jsonArray=new JSONArray();
jsonArray.add(latLng.longitude);
jsonArray.add(latLng.latitude);
list.add(jsonArray.toString());

answered Jan 2, 2017 at 8:20

ρяσѕρєя K

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Comments

EKN · Accepted Answer · 2017-01-02 08:20:57Z

0

You are creating array list with wrong type.

You must use List<nodes> nodes = new ArrayList<>() instead of List<Double> nodes = new ArrayList<>()

answered Jan 2, 2017 at 8:20

EKN

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1 Comment

EKN Over a year ago

I know. But it is possible to create a list with type node(longitude and latitude saved array), and we can store each node object in to the list. I think it is the easy way to fix the issue.

noobEinstien · Accepted Answer · 2017-01-02 08:28:45Z

0

Why don't you create

List<LatLong> nodes=new ArrayList();

And add LatLong directly

nodes.add(latLong);

And take the data

for(...){
    LatLong latLong=nodes.get(int);
    double lat=laLong.lattitude;
    double longtude=latLong.longitude;
}

answered Jan 2, 2017 at 8:28

noobEinstien

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Comments

Sadiq Md Asif · Accepted Answer · 2017-01-02 08:29:13Z

0

You aren't initializing the nodes each time you add data. thus it's not being in that format. Implement in this way.

List<List<Double>> list = new ArrayList<>();

         //loop to add add data
        for(...){
        List<Double>nodes=new ArrayList<>();
        nodes.add(latLng.longitude);
        nodes.add(latLng.latitude);
        list.add(nodes);
        }

answered Jan 2, 2017 at 8:29

Sadiq Md Asif

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Comments

Andreas · Accepted Answer · 2017-01-02 08:55:35Z

The easiest, if you are doing constants and don't need to re-size the lists, is to use Arrays.asList():

List<List<Double>> nodes = Arrays.asList(
        Arrays.asList(90.35911560058594, 23.762723181676783),
        Arrays.asList(90.36435127258301, 23.764608467290504),
        Arrays.asList(90.36520957946776, 23.764922678903957),
        Arrays.asList(90.36606788635254, 23.76327305946888 ),
        Arrays.asList(90.36941528320312, 23.763901488386157),
        Arrays.asList(90.3706169128418 , 23.76445136119925 ),
        Arrays.asList(90.36735534667969, 23.772070788117777),
        Arrays.asList(90.3665828704834 , 23.77324901017239 ),
        Arrays.asList(90.3614330291748 , 23.773327557929896),
        Arrays.asList(90.35877227783203, 23.76979286188437 ),
        Arrays.asList(90.35911560058594, 23.76979286188437 )
);
System.out.println(nodes);

Output

[[90.35911560058594, 23.762723181676783], [90.36435127258301, 23.764608467290504], [90.36520957946776, 23.764922678903957], [90.36606788635254, 23.76327305946888], [90.36941528320312, 23.763901488386157], [90.3706169128418, 23.76445136119925], [90.36735534667969, 23.772070788117777], [90.3665828704834, 23.77324901017239], [90.3614330291748, 23.773327557929896], [90.35877227783203, 23.76979286188437], [90.35911560058594, 23.76979286188437]]

If you need to re-size the nodes list, do the following. No need to do that for each node, since they are always size 2.

List<List<Double>> nodes = new ArrayList<>(Arrays.asList(
        Arrays.asList(90.35911560058594, 23.762723181676783),
         . . .
        Arrays.asList(90.35911560058594, 23.76979286188437 )
));

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