创建一个不可修改的Map

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class CreateUnmodifiableMap {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    System.out.println(map());
}
/**
 * @param entries the <i>final</i> set of entries to add to the newly created <i>unmodifiable</i> map
 * @return an <i>unmodifiable</i> map with all given entries
 */
public static <K, V> Map<K, V> map(final Entry<K, V>... entries) {
    final HashMap<K, V> map = new HashMap<K, V>(entries.length);
    for (final Entry<K, V> entry : entries) {
        map.put(entry.getKey(), entry.getValue());
    }
    return Collections.unmodifiableMap(map);
}

public static <K, V> Map<K, V> map() {
    return new HashMap<K, V>();
}

/**
 * @return an <b>UNMODIFIABLE</b> Map&lt;K, V&gt;
 */
public static <K, V> Map<K, V> unmodifiableMap(
        final Map<? extends K, ? extends V> m) {
    return (m == null) ? Collections.<K, V> emptyMap() : Collections
            .unmodifiableMap(m);
}

}
Console：
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