Create unmodifiable Collection - Java Collection Framework

Java examples for Collection Framework:Collections Utility Methods

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Description

Create unmodifiable Collection

Demo Code


//package com.java2s;
import java.util.ArrayList;

import java.util.Collection;
import java.util.Collections;

import java.util.LinkedList;
import java.util.List;

public class Main {
    public static void main(String[] argv) {
        Collection c = java.util.Arrays.asList("asdf", "java2s.com");
        System.out.println(unmodifiableCollection(c));
    }//from www .  j a v  a  2 s  .c  om

    /**
     * @return an <b>UNMODIFIABLE</b> Collection&lt;T&gt;
     */
    public static <T> Collection<T> unmodifiableCollection(
            final Collection<? extends T> c) {
        return (c == null) ? Collections.<T> emptyList() : Collections
                .unmodifiableCollection(c);
    }

    public static <T> List<T> asList(final Iterable<? extends T> iterable) {
        return (iterable instanceof Collection) ? new LinkedList<T>(
                (Collection<? extends T>) iterable) : new LinkedList<T>() {
            private static final long serialVersionUID = 3109256773218160485L;
            {
                if (iterable != null) {
                    for (final T t : iterable) {
                        add(t);
                    }
                }
            }
        };
    }

    public static <T> List<T> asList(final T t, final T... ts) {
        final ArrayList<T> list = new ArrayList<T>(ts.length + 1);
        list.add(t);
        Collections.addAll(list, ts);
        return list;
    }
}

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