Example usage for java.util Collection size

Introduction

In this page you can find the example usage for java.util Collection size.

Prototype

int size();

Source Link

Document

Returns the number of elements in this collection.

Usage

From source file:Main.java

public static String toString(Collection<?> collection) {
    StringBuilder sb = new StringBuilder(collection.size() * 2);

    for (Object item : collection) {
        sb.append(item).append(",");
    }//from   www .  j a v a2  s  .  co  m
    // sb.deleteCharAt(sb.lastIndexOf(","));
    return sb.toString();
}

From source file:Main.java

/**
 * Converts a collection to a list by either casting or creating a concrete
 * list depending on the type of collection given.
 * @param <T> The type of the elements in the collection.
 * @param c the collection. If <code>null</code>, <code>null</code> is
 *        returned.//from w  w  w. j  av  a  2  s  .c o m
 * @return {@link List} containing the same elements as the given
 *         {@link Collection} param.
 */
public static <T> List<T> listFromCollection(Collection<T> c) {
    if (c == null)
        return null;
    if (c.size() < 1) {
        return new ArrayList<T>(0);
    }
    return (c instanceof List<?>) ? (List<T>) c : new ArrayList<T>(c);
}

From source file:Main.java

public static int[] toIntArray(Collection<Integer> ints) {

    final int[] result = new int[ints.size()];
    int upto = 0;
    for (int v : ints) {
        result[upto++] = v;/*  w  w w  .j  a v  a2s  . c o m*/
    }

    // paranoia:
    assert upto == result.length;

    return result;
}

From source file:Main.java

/**
 * Determines the size of the specified Collection.  If the Collection is null or contains no elements, then the
 * size of the Collection is 0, otherwise the size of the Collection is determined by it's size() method.
 * //from   w  ww.j  ava2 s .  c om
 * @param collection the Collection who's size is being determined.
 * @return an integer value specifying the size of the Collection.
 * @see java.util.Collection#size()
 */
public static int size(final Collection collection) {
    return (collection == null ? 0 : collection.size());
}

From source file:Main.java

/**
 * Convert a collection to an array//  w  ww  .  jav  a  2s . c  om
 * 
 * @param col
 * @return
 */
@SuppressWarnings("unchecked")
public static <T> T[] toArray(Collection<T> col, Class<? super T> c) {
    int size = col.size();
    T[] array = (T[]) Array.newInstance(c, size);
    col.toArray(array);

    return array;
}

From source file:Main.java

public static boolean isNotEmpty(Collection<?> collection) {
    return (collection != null) && (collection.size() > 0);
}

From source file:Main.java

public static <T> boolean contains(T elem, Collection<T> collection) {
    if (collection != null && collection.size() > 0) {
        for (T ds : collection) {
            if (elem.equals(ds)) {
                return true;
            }/*from   w ww  . jav a 2 s.  co  m*/
        }
    }
    return false;
}

From source file:Main.java

/**
 * Returns true if the collection is null or 0-length.
 *
 * @param collection the collection to be examined
 * @return true if str collection null or zero length
 *///from w ww  .  ja  v  a2 s .c  om
public static boolean isEmpty(Collection<?> collection) {
    if (collection == null || collection.isEmpty() || collection.size() == 0) {
        return true;
    } else {
        return false;
    }
}

From source file:Main.java

/**
 * Return <code>true</code> if the supplied Collection is not <code>null</code>
 * and contain only one element. Otherwise, return <code>false</code>.<br>
 *
 * @param collection the Collection to be checked
 * @return whether the given Collection is Single
 *///  w w  w. java2s.c  o m
public static boolean isSingle(Collection<?> collection) {
    return (collection != null && collection.size() == 1);
}

From source file:Main.java

/**
 * Validate given collection argument isn't null or empty string.
 *
 * @param arg argument to validate// w  ww. ja  v  a  2 s  .c om
 * @param argName name of the argument to show in error message
 * @throws IllegalArgumentException
 */
public static <T> void notNullOrEmpty(Collection<T> arg, String argName) {
    if (arg == null || arg.size() < 1) {
        throw new IllegalArgumentException("argument is null: " + argName);
    }
}