Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

import java.util.Collections;

import java.util.Map;
import java.util.Set;

public class Main {
    /**
     * Returns a set backed by the specified map.  The resulting set displays
     * the same ordering, concurrency, and performance characteristics as the
     * backing map.  In essence, this factory method provides a {@link Set}
     * implementation corresponding to any {@link Map} implementation.  There
     * is no need to use this method on a {@link Map} implementation that
     * already has a corresponding {@link Set} implementation (such as {@link
     * HashMap} or {@link TreeMap}).
     *
     * <p>Each method invocation on the set returned by this method results in
     * exactly one method invocation on the backing map or its <tt>keySet</tt>
     * view, with one exception.  The <tt>addAll</tt> method is implemented
     * as a sequence of <tt>put</tt> invocations on the backing map.
     *
     * <p>The specified map must be empty at the time this method is invoked,
     * and should not be accessed directly after this method returns.  These
     * conditions are ensured if the map is created empty, passed directly
     * to this method, and no reference to the map is retained, as illustrated
     * in the following code fragment:
     * <pre>
     *    Set&lt;Object&gt; weakHashSet = Collections.newSetFromMap(
     *        new WeakHashMap&lt;Object, Boolean&gt;());
     * </pre>
     *
     * @param map the backing map
     * @return the set backed by the map
     * @throws IllegalArgumentException if <tt>map</tt> is not empty
     */
    public static <E> Set<E> newSetFromMap(Map<E, Boolean> map) {
        return Collections.newSetFromMap(map);
    }
}