“Cannot create generic array of ..” - how to create an Array of Map?

Question

I would like to use simpleJdbcInsert class and executeBatch method

public int[] executeBatch(Map[] batch)

http://stati

Answer 1

I have had some difficulty with this, but I have figured out a few things that I will share as simply as possible.

My experience with generics is limited to collections, so I use them in the class definitions, such as:

public class CircularArray {

which contains the data member:

private E[] data;

But you can't make and array of type generic, so it has the method:

@SuppressWarnings("unchecked")
private E[] newArray(int size)
{
    return (E[]) new Object[size];  //Create an array of Objects then cast it as E[]
}

In the constructor:

data = newArray(INITIAL_CAPACITY);  //Done for reusability

This works for generic generics, but I needed a list that could be sorted: a list of Comparables.

public class SortedCircularArray> { 
//any E that implements Comparable or extends a Comparable class

which contains the data member:

private E[] data;

But our new class throws java.lang.ClassCastException:

@SuppressWarnings("unchecked")
private E[] newArray(int size)
{
    //Old: return (E[]) new Object[size];  //Create an array of Objects then cast it as E[]
    return (E[]) new Comparable[size];  //A comparable is an object, but the converse may not be
}

In the constructor everything is the same:

data = newArray(INITIAL_CAPACITY);  //Done for reusability

I hope this helps and I hope our more experienced users will correct me if I've made mistakes.