Example usage for java.util Collection isEmpty

Introduction

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

Prototype

boolean isEmpty();

Source Link

Document

Returns true if this collection contains no elements.

Usage

From source file:Main.java

private static SSLContext sslContextForTrustedCertificates(InputStream in) {
    try {//from w w  w  .  j  a v  a 2 s .  c o m
        CertificateFactory e = CertificateFactory.getInstance("X.509");
        Collection certificates = e.generateCertificates(in);
        if (certificates.isEmpty()) {
            throw new IllegalArgumentException("expected non-empty set of trusted certificates");
        } else {
            char[] password = "password".toCharArray();
            KeyStore keyStore = newEmptyKeyStore(password);
            int index = 0;
            Iterator keyManagerFactory = certificates.iterator();
            while (keyManagerFactory.hasNext()) {
                Certificate trustManagerFactory = (Certificate) keyManagerFactory.next();
                String sslContext = Integer.toString(index++);
                keyStore.setCertificateEntry(sslContext, trustManagerFactory);
            }

            KeyManagerFactory var10 = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
            var10.init(keyStore, password);
            TrustManagerFactory var11 = TrustManagerFactory
                    .getInstance(TrustManagerFactory.getDefaultAlgorithm());
            var11.init(keyStore);
            SSLContext var12 = SSLContext.getInstance("TLS");
            var12.init(var10.getKeyManagers(), var11.getTrustManagers(), new SecureRandom());
            return var12;
        }
    } catch (Exception var9) {
        var9.printStackTrace();
    }
    return null;
}

From source file:Main.java

public static <T> T single(Collection<T> cl, boolean force, Object msg) {
    String amsg = msg == null ? "" : "," + msg.toString();
    if (cl.isEmpty()) {
        if (force) {
            throw new RuntimeException("force:" + cl + amsg);
        } else {/* www .ja va2 s  . c  om*/
            return null;
        }
    } else if (cl.size() > 1) {
        throw new RuntimeException("tomuch:" + cl + amsg);
    } else {
        return cl.iterator().next();
    }
}

From source file:Main.java

public static <T> T getFirstElement(Collection<T> collection, T defaultValue) {
    T elem = defaultValue;/*from  w  w w  .java  2  s. com*/
    if (collection != null && !collection.isEmpty()) {
        if (List.class.isAssignableFrom(collection.getClass())) {
            elem = ((List<T>) collection).get(0);
        } else {
            for (T item : collection) {
                elem = item;
                break;
            }
        }
    }
    return elem;
}

From source file:com.github.horrorho.inflatabledonkey.cloud.clients.SnapshotClient.java

public static List<Snapshot> snapshots(HttpClient httpClient, CloudKitty kitty, ProtectionZone zone,
        Collection<SnapshotID> snapshotIDs) throws IOException {

    if (snapshotIDs.isEmpty()) {
        return new ArrayList<>();
    }/*  w w  w .  ja v a 2  s  .  c o  m*/

    List<String> snapshots = snapshotIDs.stream().map(SnapshotID::id).collect(Collectors.toList());

    List<CloudKit.RecordRetrieveResponse> responses = kitty.recordRetrieveRequest(httpClient, "mbksync",
            snapshots);
    logger.debug("-- manifests() - responses: {}", responses);

    return responses.stream().filter(CloudKit.RecordRetrieveResponse::hasRecord)
            .map(CloudKit.RecordRetrieveResponse::getRecord).map(r -> manifests(r, zone))
            .filter(Optional::isPresent).map(Optional::get).collect(Collectors.toList());
}

From source file:com.anhth12.lambda.common.math.VectorMath.java

public static RealMatrix transposeTimesSelf(Collection<float[]> M) {
    if (M == null || M.isEmpty()) {
        return null;
    }//from   w ww  .j  av a2 s .com
    int features = 0;
    RealMatrix result = null;
    for (float[] vector : M) {
        if (result == null) {
            features = vector.length;
            result = new Array2DRowRealMatrix(features, features);
        }
        for (int row = 0; row < features; row++) {
            float rowValue = vector[row];
            for (int col = 0; col < features; col++) {
                result.addToEntry(row, col, rowValue * vector[col]);
            }
        }
    }
    return result;
}

From source file:Main.java

/**
 * Determine the index position of the first occurrence of the given object instance in the given collection. Thereby avoiding the use of
 * {@link Object#equals(Object) equals(Object)} and {@link Object#hashCode() hashCode()} in the {@link java.util.List#indexOf(Object)
 * indexOf(Object)} implementation of the collection/list itself.
 *
 * <p>/*from  w  ww . j a va2  s .  c  om*/
 * This check is supposed to be faster and can be used with objects, that are missing proper implementations of those methods. Additionally,
 * objects that are deemed {@link Object#equals(Object) equal} but not identical are ignored.
 * </p>
 *
 * @param collection
 *            collection to check for contained instance
 * @param instance
 *            specific object instance to check for
 * @param <T>
 *            type of the object to check for
 * @return position of the given instance in the collection (not just of an equal object)
 */
public static <T> int indexOfInstance(final Collection<? extends T> collection, final T instance) {
    if (collection != null && !collection.isEmpty()) {
        int index = 0;
        for (final T collectionElement : collection) {
            if (collectionElement == instance) {
                return index;
            }
            index++;
        }
    }
    return -1;
}

From source file:Main.java

/**
 * Returns a String representation of the given collection by separating the
 * elements with the given separator.//from  w  ww .ja  v a 2  s.  co  m
 * 
 * @param collection
 * @param separator
 * @return
 */
public static String toString(Collection<? extends Object> collection, String separator) {
    if (collection == null || collection.isEmpty()) {
        return "";
    }
    StringBuilder builder = new StringBuilder();
    int count = collection.size();
    for (Object obj : collection) {
        builder.append(obj);
        if (--count > 0) {
            builder.append(separator);
        }
    }
    return builder.toString();
}

From source file:Main.java

/**
 * Returns <code>true</code> iff all elements of {@code coll2} are also contained
 * in {@code coll1}. The cardinality of values in {@code coll2} is not taken into account,
 * which is the same behavior as {@link Collection#containsAll(Collection)}.
 * <p>/*from   w w  w. j a  v a2 s  .  co  m*/
 * In other words, this method returns <code>true</code> iff the
 * {@link #intersection} of <i>coll1</i> and <i>coll2</i> has the same cardinality as
 * the set of unique values from {@code coll2}. In case {@code coll2} is empty, {@code true}
 * will be returned.
 * <p>
 * This method is intended as a replacement for {@link Collection#containsAll(Collection)}
 * with a guaranteed runtime complexity of {@code O(n + m)}. Depending on the type of
 * {@link Collection} provided, this method will be much faster than calling
 * {@link Collection#containsAll(Collection)} instead, though this will come at the
 * cost of an additional space complexity O(n).
 *
 * @param coll1  the first collection, must not be null
 * @param coll2  the second collection, must not be null
 * @return <code>true</code> iff the intersection of the collections has the same cardinality
 *   as the set of unique elements from the second collection
 * @since 4.0
 */
public static boolean containsAll(final Collection<?> coll1, final Collection<?> coll2) {
    if (coll2.isEmpty()) {
        return true;
    } else {
        final Iterator<?> it = coll1.iterator();
        final Set<Object> elementsAlreadySeen = new HashSet<Object>();
        for (final Object nextElement : coll2) {
            if (elementsAlreadySeen.contains(nextElement)) {
                continue;
            }

            boolean foundCurrentElement = false;
            while (it.hasNext()) {
                final Object p = it.next();
                elementsAlreadySeen.add(p);
                if (nextElement == null ? p == null : nextElement.equals(p)) {
                    foundCurrentElement = true;
                    break;
                }
            }

            if (foundCurrentElement) {
                continue;
            } else {
                return false;
            }
        }
        return true;
    }
}

From source file:net.lmxm.ute.UteTestAssert.java

/**
 * Assert empty./*from   www .j  av a2s .c  o  m*/
 * 
 * @param <E> the element type
 * @param message the message
 * @param collection the collection
 */
public static <E> void assertEmpty(final String message, final Collection<E> collection) {
    assertTrue(message, collection.isEmpty());
}

From source file:Main.java

/**
 * Return {@code true} if the supplied Collection is {@code null} or empty.
 * Otherwise, return {@code false}.//from  w w w. ja  va  2 s . c o m
 *
 * @param collection the Collection to check
 * @return whether the given Collection is empty
 */
public static boolean isEmpty(Collection<?> collection) {
    return (collection == null || collection.isEmpty());
}