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 collectionAsString(Collection<?> collection) {
    if (collection == null)
        return "[null]";
    if (collection.size() == 0)
        return "[empty]";
    StringBuilder builder = new StringBuilder();
    for (Object obj : collection) {
        builder.append(obj).append(", ");
    }//from w  w w  . java  2s . co m
    builder.deleteCharAt(builder.length() - 1);
    return builder.toString();
}

From source file:Main.java

/**
 * Converts a typed {@link Collection} to a typed array.
 * // w  ww .j  a  v  a 2 s  . c  o  m
 * @param type
 *            the type class
 * @param collection
 *            the collection to convert to an array.
 * @return the array.
 */
@SuppressWarnings("unchecked")
public static <T> T[] toArray(Class<T> type, Collection<T> collection) {
    return collection.toArray((T[]) Array.newInstance(type, collection.size()));
}

From source file:Main.java

public static <T> T get(final Collection<T> collection, final int index) {
    if (collection.size() < index + 1) {
        return null;
    }//from  w ww  . j ava 2s  . c o  m
    int i = 0;
    for (T item : collection) {
        if (i == index) {
            return item;
        }
        i++;
    }
    return null;
}

From source file:Main.java

/**
 * Nullsafe method returning the number of elements the incoming collection contains.
 *
 * @param c Collection of Objects to count the number of elements from
 * @return int containing the number of the elements in the collection, or -1 if the collection is null
 *//*  w  ww .j  a va 2  s .  c  om*/
public static int size(Collection c) {
    int size = -1;

    if (c != null) {
        size = c.size();
    }

    return size;
}

From source file:Main.java

/**
 * Checks whether the COLLECTION is not NULL and has at least one element.
 * //from   w  w w  . j av a2s.  c om
 * @param <T>
 *            the generic type
 * @param collection
 *            the collection
 * @return true, if successful
 */
public static <T> boolean hasElements(Collection<T> collection) {
    return (null != collection && collection.size() > 0);
}

From source file:com.teradata.benchto.service.model.AggregatedMeasurement.java

public static AggregatedMeasurement aggregate(MeasurementUnit unit, Collection<Double> values) {
    if (values.size() < 2) {
        Double value = Iterables.getOnlyElement(values);
        return new AggregatedMeasurement(unit, value, value, value, 0.0, 0.0);
    }//from ww  w.  j  ava  2 s .c  o  m
    DescriptiveStatistics statistics = new DescriptiveStatistics(
            values.stream().mapToDouble(Double::doubleValue).toArray());

    double stdDevPercent = 0.0;
    if (statistics.getStandardDeviation() > 0.0) {
        stdDevPercent = (statistics.getStandardDeviation() / statistics.getMean()) * 100;
    }

    return new AggregatedMeasurement(unit, statistics.getMin(), statistics.getMax(), statistics.getMean(),
            statistics.getStandardDeviation(), stdDevPercent);
}

From source file:Main.java

public static boolean equalsIgnoreOrder(Collection<?> c1, Collection<?> c2) {
    if (c1 == c2) {
        return true;
    }//ww w.  j av  a  2s.  c  om
    if (c1.size() != c2.size()) {
        return false;
    }
    return c1.containsAll(c2) && c2.containsAll(c1);
}

From source file:Main.java

/**
 * *//  www  .  ja v a 2s .  co  m
 * Get size of Collection and NullPointerException safe
 *
 * @param collection
 * @return -1 if collction is null then else return collection's size
 */
public static int getSize(Collection collection) {
    if (collection == null) {
        return -1;
    }
    return collection.size();
}

From source file:Main.java

public static <ELEMENT> HashSet<ELEMENT> newHashSet(Collection<ELEMENT> elements) {
    final HashSet<ELEMENT> set = newHashSetSized(elements.size());
    set.addAll(elements);//ww w .  j  av a 2  s.c  om
    return set;
}

From source file:Main.java

public static Object findOne(Collection coll) {
    if (coll.isEmpty()) {
        return null;
    } else if (coll.size() > 1) {
        throw new RuntimeException("Expected only one member in collection, found many: " + coll.toString());
    } else {//from w w  w .  j a  v a  2 s  .  c  o m
        return coll.iterator().next();
    }
}