动态二维数组

Question

I have a program that that creates a list of values. (String, double, double, double ) I would like to store these values in an array, vector, or array that is array[x][4]. How can i do this?

Answer 1

You can use an ArrayList of arrays of Object s:

eg

List<Object[]> list = new ArrayList<Object[]>();

list.add(new Object[]{"string", 2d, 1d, 0d});

Update :

They can be printed as follows (since we know that the array elements are String and Double s:

for(Object[] row : list) {
    System.out.println(row[0] + " " + row[1] + " " + row[2] + " " + row[3]);
}

But I do believe that it's a lot better to use a class here for OOP.

Answer 2

To keep it simple:

Create Data Object class with 4 fields:

class MyDataObject {
   String firstParameter;
   double secondParameter;
   double thirdParameter;
   double fourthParameter;
}

Then store this object in List:

List<MyDataObject> = new ArrayList<MyDataObject>();

if your class is present in the same java file (so it is in the same package) - you can avoid using accessors because of default package visibility access.

Answer 3

What if you create a class and declare those four fields within it and store the objects of that class into an ArrayList as shown in the following example.

final class DemoClass
{
    String str="";
    double a;
    double b;
    double c;

    public DemoClass(String str, double a, double b, double c)
    {
        this.str=str;
        this.a=a;
        this.b=b;
        this.c=c;
    }

    public void doSomething()
    {
        //...
    }
}

final public class Main
{
    public static void main(String...args)
    {
        DemoClass dc=new DemoClass("SomeStrValue", 1, 2, 3);
        List<DemoClass>list=new ArrayList<DemoClass>();
        list.add(dc);
    }
}

Would make it easier I think.