Convert ArrayLIst of objects to String 2D Array

Question

I'm trying to convert an ArrayList of type Car to a 2D Array. Unfortunetly I don't have Java 8. I'm on java 7 and with java 8 there's supposed to be an easy way to do it which is :

String[][] stringArray = miniTable.stream().map(u -> u.toArray(new String[0])).toArray(String[][]::new);

ArrayList:

miniTable = new ArrayList<Car>();
      miniTable.add(new Car("1123", "New York, NY", "Green"));
      miniTable.add(new Car("3321", "Tampa, FL", "Blue"));
      miniTable.add(new Car("3346", "Atlanta, GA", "Red"));,

Logic

     int count=0;
      String[][] content = new String [3][5];
      //Convert regular array  to [][]
      for(int i=0;i<3;i++)
      {
          for(int j=0;j<5;j++)
          {
              if(count == miniTable.size()) break;
                content[i][j]= miniTable.get(i).getNumber();
                content[i][j]= miniTable.get(i).getOrigin();
                content[i][j]= miniTable.get(i).getColor();                   
                count++;
          }
      }

Desired Ouput:

NiVeR · Accepted Answer · 2018-08-03 20:55:00Z

1

I don't see why you can't use the array list to map to the table but to construct the array you can do something like this:

String[][] content = new String [3][5];
for(int i = 0; i < miniTable.size(); i++)
{
    Car car = miniTable.get(i);
    content[i][0] = car.getName();
    content[i][1] = car.getManufacturer();
    ....
}

answered Aug 3, 2018 at 20:55

NiVeR

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3 Comments

Patricio Vargas Over a year ago

How would you map it using java 7? you solution worked it was very simple. Thanks

NiVeR Over a year ago

@PatricioVargas Welcome. I meant you probably don't need this intermediate step of constructing the 2D array to visualize in on the table but you didn't show more code and I can't say. Anyway if this works it is fine.

Patricio Vargas Over a year ago

Your solution worked, it's simple. I was just curious on how to do it with the map thing. Thanks for taking your time to answer!

davidxxx · Accepted Answer · 2018-08-03 20:56:07Z

1

The inner loop is not required. You want to map each Car field as column values of the 2d array.

So change :

for(int j=0;j<5;j++)
{
    if(count == miniTable.size()) break;
    content[i][j]= miniTable.get(i)+"";
    count++;    
}

to :

int j=0;
Car car =  miniTable.get(i);
content[i][j++]= car.getName();
content[i][j++]= car.getOrigin();
content[i][j++]= car.getColor();

answered Aug 3, 2018 at 20:56

davidxxx

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