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 <T> boolean hasDuplicates(Collection<T> collection) {
    Set<T> set = new HashSet<T>(collection);
    return set.size() != collection.size();
}

From source file:Main.java

public static <T> String toString(Collection<T> c, String prefix, String sep, String suffix) {
    if (c == null || c.size() == 0)
        return prefix + suffix;
    Iterator<T> it = c.iterator();
    String result = prefix + it.next();
    while (it.hasNext())
        result += sep + it.next();/*from w  w w  .ja v a  2s.  co m*/
    return result + suffix;
}

From source file:Main.java

/**
 * Assesses all the possible containment relations between collections A and B with one call.<br>
 * Returns an int with bits set, according to a "Venn Diagram" view of A vs B.<br>
 * NOT_A_SUPERSET_B: a - b != {}<br>
 * NOT_A_DISJOINT_B: a * b != {}  // * is intersects<br>
 * NOT_A_SUBSET_B: b - a != {}<br>
 * Thus the bits can be used to get the following relations:<br>
 * for A_SUPERSET_B, use (x & CollectionUtilities.NOT_A_SUPERSET_B) == 0<br>
 * for A_SUBSET_B, use (x & CollectionUtilities.NOT_A_SUBSET_B) == 0<br>
 * for A_EQUALS_B, use (x & CollectionUtilities.NOT_A_EQUALS_B) == 0<br>
 * for A_DISJOINT_B, use (x & CollectionUtilities.NOT_A_DISJOINT_B) == 0<br>
 * for A_OVERLAPS_B, use (x & CollectionUtilities.NOT_A_DISJOINT_B) != 0<br>
 *///from ww w  . j a v a 2  s.  c  o m
public static int getContainmentRelation(Collection a, Collection b) {
    if (a.size() == 0) {
        return (b.size() == 0) ? ALL_EMPTY : NOT_A_SUPERSET_B;
    } else if (b.size() == 0) {
        return NOT_A_SUBSET_B;
    }
    int result = 0;
    // WARNING: one might think that the following can be short-circuited, by looking at
    // the sizes of a and b. However, this would fail in general, where a different comparator is being
    // used in the two collections. Unfortunately, there is no failsafe way to test for that.
    for (Iterator it = a.iterator(); result != 6 && it.hasNext();) {
        result |= (b.contains(it.next())) ? NOT_A_DISJOINT_B : NOT_A_SUBSET_B;
    }
    for (Iterator it = b.iterator(); (result & 3) != 3 && it.hasNext();) {
        result |= (a.contains(it.next())) ? NOT_A_DISJOINT_B : NOT_A_SUPERSET_B;
    }
    return result;
}

From source file:Main.java

/**
 * Converts Collection to array. /*from   w ww  .  jav  a 2  s  .c o  m*/
 * @param <T>
 * @param col
 * @param cls
 * @return 
 * @see java.util.Collection#toArray(T[]) 
 */
public static <T> T[] toArray(Collection<T> col, Class<T> cls) {
    T[] arr = (T[]) Array.newInstance(cls, col.size());
    return col.toArray(arr);
}

From source file:Main.java

public static <T> List<T> concat(Collection<? extends T> xs, Collection<? extends T> ys) {
    ArrayList<T> result = new ArrayList<>(xs.size() + ys.size());
    result.addAll(xs);/*from  www. j  a v  a2 s .  c om*/
    result.addAll(ys);
    return result;
}

From source file:Main.java

public static <T> boolean isDistinct(Collection<T> in) {
    if (in == null) {
        return true;
    }//from ww  w  .  j  ava2 s  .  com
    return in.size() == distinct(in).size();
}

From source file:Main.java

public static boolean isEmpty(Collection<?> values) {
    return values == null || values.size() == 0;
}

From source file:com.appdynamicspilot.util.ArgumentUtils.java

public static boolean isNullOrEmpty(Collection argumentValue) {
    return (isNull(argumentValue) || argumentValue.size() == 0);
}

From source file:Main.java

public static int size(final Collection collection) {
    return null != collection ? collection.size() : 0;
}

From source file:Main.java

/**
 * Convert a Collection of Numbers to an array of primitive ints
 * Null values will be skipped in the array 
 * @param items//from w ww.j a va  2  s. com
 * @return
 */
public static int[] toIntArray(Collection<? extends Number> items) {
    int ret[] = new int[items.size()];
    int idx = 0;
    for (Number n : items) {
        if (n != null)
            ret[idx] = n.intValue();
        idx += 1;
    } // FOR
    return (ret);
}