Convert various data structure as Array - Java Collection Framework

Java examples for Collection Framework:Array Convert

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Description

Convert various data structure as Array

Demo Code


//package com.book2s;
import java.util.ArrayList;
import java.util.Collection;

import java.util.Iterator;
import java.util.List;

public class Main {
    public static void main(String[] argv) {
        Collection collection = java.util.Arrays.asList("asdf",
                "book2s.com");
        System.out.println(java.util.Arrays.toString(asArray(collection)));
    }//w  w w  . ja v  a  2  s .  c o  m

    @SuppressWarnings("unchecked")
    public static <E> E[] asArray(final Collection<? extends E> collection) {
        return collection.toArray((E[]) new Object[collection.size()]);
    }

    @SuppressWarnings("unchecked")
    public static <E> E[] asArray(final Object... array) {
        final E[] elements = (E[]) new Object[array.length];
        for (int i = 0; i < array.length; i++) {
            elements[i] = (E) array[i];
        }
        return elements;
    }

    public static <E> List<E> asList(
            @SuppressWarnings("unchecked") final E... array) {
        List<E> list = new ArrayList<>(array.length);
        for (E element : array) {
            list.add(element);
        }
        return list;
    }

    public static <E> List<E> asList(final Iterator<? extends E> iterator) {
        List<E> list = new ArrayList<>();
        while (iterator.hasNext()) {
            list.add(iterator.next());
        }
        return list;
    }

    public static <E> String toString(Iterator<E> iterator) {
        if (iterator == null || !iterator.hasNext()) {
            return "[]";
        }
        StringBuilder builder = new StringBuilder();
        builder.append('[');
        while (iterator.hasNext()) {
            builder.append(iterator.next()).append(',').append(' ');
        }
        return builder.append(']').toString();
    }
}

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