Java Collection to Array convertToArray(Collection collection)

Description

convert To Array

License

Open Source License

Declaration

public static Object convertToArray(Collection collection) 

Method Source Code

//package com.java2s;
/*//from  ww  w .  j av  a 2 s.  c o m
 * BackwardCompatibilityHelper.java
 *
 * Tigase Jabber/XMPP Server
 * Copyright (C) 2004-2016 "Tigase, Inc." <office@tigase.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. Look for COPYING file in the top folder.
 * If not, see http://www.gnu.org/licenses/.
 */

import java.util.Collection;

import java.util.Iterator;

public class Main {
    public static Object convertToArray(Collection collection) {
        Iterator iter = collection.iterator();
        if (!iter.hasNext())
            return null;

        Class objCls = iter.next().getClass();
        if (objCls == Integer.class) {
            return convertToIntArray(collection);
        } else if (objCls == Long.class) {
            return convertToLongArray(collection);
        } else if (objCls == Double.class) {
            return convertToDoubleArray(collection);
        } else if (objCls == Float.class) {
            return convertToFloatArray(collection);
        } else if (objCls == Boolean.class) {
            return convertToBoolArray(collection);
        } else if (objCls == String.class) {
            return convertToStringArray(collection);
        }
        return null;
    }

    public static Object convertToIntArray(Collection col) {
        int[] arr = new int[col.size()];
        int pos = 0;
        Iterator iter = col.iterator();
        while (iter.hasNext()) {
            Number v = (Number) iter.next();
            arr[pos++] = v.intValue();
        }
        return arr;
    }

    public static Object convertToLongArray(Collection col) {
        long[] arr = new long[col.size()];
        int pos = 0;
        Iterator iter = col.iterator();
        while (iter.hasNext()) {
            Number v = (Number) iter.next();
            arr[pos++] = v.longValue();
        }
        return arr;
    }

    public static Object convertToDoubleArray(Collection col) {
        double[] arr = new double[col.size()];
        int pos = 0;
        Iterator iter = col.iterator();
        while (iter.hasNext()) {
            Number v = (Number) iter.next();
            arr[pos++] = v.doubleValue();
        }
        return arr;
    }

    public static Object convertToFloatArray(Collection col) {
        float[] arr = new float[col.size()];
        int pos = 0;
        Iterator iter = col.iterator();
        while (iter.hasNext()) {
            Number v = (Number) iter.next();
            arr[pos++] = v.floatValue();
        }
        return arr;
    }

    public static Object convertToBoolArray(Collection col) {
        boolean[] arr = new boolean[col.size()];
        int pos = 0;
        Iterator iter = col.iterator();
        while (iter.hasNext()) {
            Boolean v = (Boolean) iter.next();
            arr[pos++] = v.booleanValue();
        }
        return arr;
    }

    public static Object convertToStringArray(Collection col) {
        String[] arr = new String[col.size()];
        int pos = 0;
        Iterator iter = col.iterator();
        while (iter.hasNext()) {
            String v = (String) iter.next();
            arr[pos++] = v;
        }
        return arr;
    }
}

Related

1. collectionToArray(Collection collection)
2. collectionToIntArray(Collection c)
3. collectionToIntArray(final Collection numbers)
4. collectionToObjectArray(Collection c)
5. collectionToObjectArray(final Collection _list)
6. convertToArray(Collection input)
7. convertToArray(Collection items)
8. toArray(Collection c)
9. toArray(Collection coll)