Java Set Intersect intersect(Set<? extends T> set1, Set<? extends T> set2)

Description

Perform the operation intersect on two given sets.

License

Apache License

Parameter

Parameter	Description
set1	input set
set2	input set

Return

the intersect of the given sets.

Declaration

public static <T> Set<T> intersect(Set<? extends T> set1, Set<? extends T> set2)

Method Source Code

//package com.java2s;
/*/*  w  w  w .j  ava2s.c o m*/
Copyright 1996-2010 Ariba, Inc.
    
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
    
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
    
$Id: //ariba/platform/util/core/ariba/util/core/SetUtil.java#16 $
*/

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import java.util.Collection;

public class Main {
    /**
    Perform the operation intersect on two given sets. The operation is
    nondestructive.<p>
        
    If one of the sets is null or empty the method returns an empty set.<p>
        
    @param set1 input set
    @param set2 input set
    @return the intersect of the given sets.
    @aribaapi ariba
    */
    public static <T> Set<T> intersect(Set<? extends T> set1, Set<? extends T> set2) {
        Set<T> s = set();
        intersect(set1, set2, s);
        return s;
    }

    /**
    Perform the operation intersect on two given sets. The operation is
    nondestructive.<p>
        
    If one of the sets is null or empty, nothing would be added to the
    result set.<p>
        
    @param set1 input set
    @param set2 input set
    @param result result set
    @throw IllegalArgumentException when result is <code>null</code>.
    @aribaapi ariba
     */
    public static <T> void intersect(Set<? extends T> set1, Set<? extends T> set2, Set<T> result) {
        if (result == null) {
            throw new IllegalArgumentException("result must not be null");
        }

        if (set1 == null || set2 == null || set1.isEmpty() || set2.isEmpty()) {
            return;
        }

        Set<? extends T> iterateThru = null;
        Set<? extends T> check = null;
        if (set1.size() > set2.size()) {
            iterateThru = set2;
            check = set1;
        } else {
            iterateThru = set1;
            check = set2;
        }

        for (Iterator<? extends T> it = iterateThru.iterator(); it.hasNext();) {
            T o = it.next();
            if (check.contains(o)) {
                result.add(o);
            }
        }
    }

    /**
    Constructs an empty optionally type-safe <code>Set</code>.<p>
        
    To construct a type-safe <code>Set</code>:<ul>
    <li><code>Set&lt;X> typesafe = SetUtil.set()</code>
    </ul>
    For a raw <code>Set</code>:<ul>
    <li><code>Set raw = SetUtil.set()</code>
    </ul>
    There will be no compile warnings either way.
        
    @return new empty Set
    @aribaapi ariba
    */
    public static <T> Set<T> set() {
        return new HashSet<T>();
    }

    /**
    Constructs a Set capable of holding a specified number
    of elements. <p/>
        
    To construct a type-safe <code>Set</code>:<ul>
    <li><code>Set&lt;X> typesafe = SetUtil.set(10)</code>
    </ul>
    For a raw <code>Set</code>:<ul>
    <li><code>Set raw = SetUtil.set(10)</code>
    </ul>
    There will be no compile warnings either way.
        
    @param initialCapacity the number of elements this Set
    is capable of holding before needing to grow.
    @return new empty Set with given initial capacity
    @aribaapi ariba
    */
    public static <T> Set<T> set(int initialCapacity) {
        return new HashSet<T>(initialCapacity);
    }

    /**
    Creates new Set with the same contents as unique elements in the given Collection.
    <p/>
        
    Given that <code>setOfX</code> is a <code>Set&lt;X></code>,
    <code>setOfY</code> is a <code>Set&lt;Y></code> (and that <code>Y</code>
    extends <code>X</code>) and
    <code>raw</code> is a <code>Set</code>, the following
    all compile validly. <ul>
    <li><code>Set&lt;X> typesafe = SetUtil.set(setOfX)</code>
    <li><code>Set&lt;X> typesafe = SetUtil.&lt;X>set(setOfY)</code>
    <li><code>Set&lt;?> unknown = SetUtil.set(setOfX)</code>
    </ul>
    The following constructs compile with an unchecked warning:<ul>
    <li><code>Set&lt;X> typesafe = SetUtil.set(raw)</code>
    <li><code>Set raw = SetUtil.set(setOfX)</code>
    </ul>
        
    @param source source collection
    @return new Set with same contents as <code>source</code>
    @exception NullPointerException  if the specified Set is null.
    @aribaapi ariba
    */
    public static <T> Set<T> set(Collection<? extends T> source) {
        return new HashSet<T>(source);
    }
}

Java Set Intersect intersect(Set set1, Set set2)

Description

License

Parameter

Return

Declaration

Method Source Code

Related