Java Collection Join join(final String separator, final Collection<T> objects)

Description

Returns a string of the form elt1.toString() [sep elt2.toString() ...

License

Open Source License

Parameter

Parameter	Description
separator	the string to use to separate objects
objects	a collection of objects. the element order is defined by the iterator over objects
T	the type of the objects

Return

a non-null string

Declaration

public static <T> String join(final String separator, final Collection<T> objects)

Method Source Code

//package com.java2s;
/*/*from   w  w w  .j a  va  2 s  .c  o  m*/
 * Copyright (c) 2010 The Broad Institute
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

import java.util.*;

public class Main {
    /**
     * join an array of strings given a seperator
     * @param separator the string to insert between each array element
     * @param strings the array of strings
     * @return a string, which is the joining of all array values with the separator
     */
    public static String join(String separator, String[] strings) {
        return join(separator, strings, 0, strings.length);
    }

    public static String join(String separator, String[] strings, int start, int end) {
        if ((end - start) == 0) {
            return "";
        }
        StringBuilder ret = new StringBuilder(strings[start]);
        for (int i = start + 1; i < end; ++i) {
            ret.append(separator);
            ret.append(strings[i]);
        }
        return ret.toString();
    }

    public static String join(String separator, int[] ints) {
        if (ints == null || ints.length == 0)
            return "";
        else {
            StringBuilder ret = new StringBuilder();
            ret.append(ints[0]);
            for (int i = 1; i < ints.length; ++i) {
                ret.append(separator);
                ret.append(ints[i]);
            }
            return ret.toString();
        }
    }

    /**
     * Returns a string of the values in joined by separator, such as A,B,C
     *
     * @param separator
     * @param doubles
     * @return
     */
    public static String join(String separator, double[] doubles) {
        if (doubles == null || doubles.length == 0)
            return "";
        else {
            StringBuilder ret = new StringBuilder();
            ret.append(doubles[0]);
            for (int i = 1; i < doubles.length; ++i) {
                ret.append(separator);
                ret.append(doubles[i]);
            }
            return ret.toString();
        }
    }

    /**
     * Returns a string of the form elt1.toString() [sep elt2.toString() ... sep elt.toString()] for a collection of
     * elti objects (note there's no actual space between sep and the elti elements).  Returns
     * "" if collection is empty.  If collection contains just elt, then returns elt.toString()
     *
     * @param separator the string to use to separate objects
     * @param objects a collection of objects.  the element order is defined by the iterator over objects
     * @param <T> the type of the objects
     * @return a non-null string
     */
    public static <T> String join(final String separator, final Collection<T> objects) {
        if (objects.isEmpty()) { // fast path for empty collection
            return "";
        } else {
            final Iterator<T> iter = objects.iterator();
            final T first = iter.next();

            if (!iter.hasNext()) // fast path for singleton collections
                return first.toString();
            else { // full path for 2+ collection that actually need a join
                final StringBuilder ret = new StringBuilder(first.toString());
                while (iter.hasNext()) {
                    ret.append(separator);
                    ret.append(iter.next().toString());
                }
                return ret.toString();
            }
        }
    }

    public static <T> String join(final String separator, final T... objects) {
        return join(separator, Arrays.asList(objects));
    }

    public static <T> List<T> append(final List<T> left, T... elts) {
        final List<T> l = new LinkedList<T>(left);
        l.addAll(Arrays.asList(elts));
        return l;
    }
}

Java Collection Join join(final String separator, final Collection objects)

Description

License

Parameter

Return

Declaration

Method Source Code

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