OnJava8-Examples/generics/GenericArray2.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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// generics/GenericArray2.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

public class GenericArray2<T> {

private Object[] array;

public GenericArray2(int sz) {

array = new Object[sz];

}

public void put(int index, T item) {

array[index] = item;

}

@SuppressWarnings("unchecked")

public T get(int index) { return (T)array[index]; }

@SuppressWarnings("unchecked")

public T[] rep() {

return (T[])array; // Unchecked cast

}

public static void main(String[] args) {

GenericArray2<Integer> gai =

new GenericArray2<>(10);

for(int i = 0; i < 10; i ++)

gai.put(i, i);

for(int i = 0; i < 10; i ++)

System.out.print(gai.get(i) + " ");

System.out.println();

try {

Integer[] ia = gai.rep();

} catch(Exception e) {

System.out.println(e);

}

/* Output:

0 1 2 3 4 5 6 7 8 9

java.lang.ClassCastException: [Ljava.lang.Object;

cannot be cast to [Ljava.lang.Integer;