Adding Multiple Values in ArrayList at a single index

Question

I have a double ArrayList in java like this.

List values = new ArrayList(2);

Now what I want t

Answer 1

You can pass an object which is refering to all the values at a particular index.

import java.util.ArrayList;

public class HelloWorld{

 public static void main(String []args){


ArrayList<connect> a=new ArrayList<connect>();

a.add(new connect(100,100,100,100,100));

System.out.println(a.get(0).p1);

System.out.println(a.get(0).p2);

System.out.println(a.get(0).p3);
}

}

class connect
{
int p1,p2,p3,p4,p5;

connect(int a,int b,int c,int d,int e)
{

this.p1=a;

this.p2=b;

this.p3=c;

this.p4=d;

this.p5=e;
}

}

Later to get a particular value at a specific index, you can do this:

a.get(0).p1;

a.get(0).p2;

a.get(0).p3;.............

and so on.

Answer 2

Use two dimensional array instead. For instance, int values[][] = new int[2][5]; Arrays are faster, when you are not manipulating much.

Answer 3

@Ahamed has a point, but if you're insisting on using lists so you can have three arraylist like this:

ArrayList<Integer> first = new ArrayList<Integer>(Arrays.AsList(100,100,100,100,100));
ArrayList<Integer> second = new ArrayList<Integer>(Arrays.AsList(50,35,25,45,65));
ArrayList<Integer> third = new ArrayList<Integer>();

for(int i = 0; i < first.size(); i++) {
      third.add(first.get(i));
      third.add(second.get(i));
}

Edit: If you have those values on your list that below:

List<double[]> values = new ArrayList<double[]>(2);

what you want to do is combine them, right? You can try something like this: (I assume that both array are same sized, otherwise you need to use two for statement)

ArrayList<Double> yourArray = new ArrayList<Double>();
for(int i = 0; i < values.get(0).length; i++) {
    yourArray.add(values.get(0)[i]);
    yourArray.add(values.get(1)[i]);
}

Answer 4

How about

1. First adding your desired result as arraylist and
2. and convert to double array as you want.

Try like this..

import java.util.ArrayList;
import java.util.List;

    public class ArrayTest {

        /**
         * @param args
         */
        public static void main(String[] args) {
            // TODO Auto-generated method stub

            // Your Prepared data. 
            List<double[]> values = new ArrayList<double[]>(2);

            double[] element1 = new double[] { 100, 100, 100, 100, 100 };
            double[] element2 = new double[] { 50, 35, 25, 45, 65 };

            values.add(element1);
            values.add(element2);

            // Add the result to arraylist.
            List<Double> temp = new ArrayList<Double>();
            for(int j=0;j<values.size(); j++) {
                for (int i = 0; i < values.get(0).length; i++) {
                    temp.add(values.get(0)[i]);
                    temp.add(values.get(1)[i]);
                }
            }

            // Convert arraylist to int[].
            Double[] result = temp.toArray(new Double[temp.size()]);
            double[] finalResult = new double[result.length]; // This hold final result.
            for (int i = 0; i < result.length; i++) {
                finalResult[i] = result[i].doubleValue();
            }

            for (int i = 0; i < finalResult.length; i++) {
                System.out.println(finalResult[i]);
            }
        }
    }

Answer 5

import java.util.*;
public class HelloWorld{

 public static void main(String []args){
  List<String> threadSafeList = new ArrayList<String>();
    threadSafeList.add("A");
    threadSafeList.add("D");
    threadSafeList.add("F");

Set<String> threadSafeList1 = new TreeSet<String>();
    threadSafeList1.add("B");
    threadSafeList1.add("C");
    threadSafeList1.add("E");
    threadSafeList1.addAll(threadSafeList);


 List mainList = new ArrayList();   
 mainList.addAll(Arrays.asList(threadSafeList1));
 Iterator<String> mainList1 = mainList.iterator();
 while(mainList1.hasNext()){
 System.out.printf("total : %s %n", mainList1.next());
 }
}
}

Answer 6

ArrayList<ArrayList> arrObjList = new ArrayList<ArrayList>();
ArrayList<Double> arrObjInner1= new ArrayList<Double>();
arrObjInner1.add(100);
arrObjInner1.add(100);
arrObjInner1.add(100);
arrObjInner1.add(100);

arrObjList.add(arrObjInner1);

You can have as many ArrayList inside the arrObjList. I hope this will help you.