Main.java Source code

Introduction

Here is the source code for Main.java

Source

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

public class Main {
    /**
     * Copies the contents of a Collection to a new, unmodifiable Collection.  If the Collection is null, an empty 
     * Collection will  be returned.
     * <p>
     * This is especially useful for methods which take Collection parameters.  Directly assigning such a Collection
     * to a member variable can allow external classes to modify internal state.  Classes may have different state 
     * depending on the size of a Collection; for example, a button might be disabled if the the Collection size is zero.  
     * If an external object can change the Collection, the containing class would have no way have knowing a 
     * modification occurred.
     * 
     * @param <T> The type of element in the Collection.
     * @param collection The Collection to copy.
     * @return A new, unmodifiable Collection which contains all of the elements of the List parameter.  Will never be 
     * null.
     */
    public static <T> Collection<T> copyToUnmodifiableCollection(Collection<T> collection) {
        if (collection != null) {
            Collection<T> collectionCopy = new ArrayList(collection);
            return Collections.unmodifiableCollection(collectionCopy);
        } else {
            return Collections.emptyList();
        }
    }
}