Java 使用链表来实现队列功能

/** * 链表元素定义 * Create by zxb on 2017/8/27 */public class Element<T> {    private Element<T> next;    private T value;    public Element<T> getNext() {        return next;    }    public void setNext(Element<T> next) {        this.next = next;    }    public T getValue() {        return value;    }    public void setValue(T value) {        this.value = value;    }}/** * 列表模板接口 * Created by zhengxb on 2017/8/27. */public interface IList<T> {    boolean pushBack(T newElement);    boolean popFront();    Element<T> front();    int size();}/** * 链表实现 * Create by zxb on 2017/8/27 */public class ListImpl<T> implements IList<T> {    private Element<T> first = null;    private Element<T> last = null;    private int size = 0;    @Override    public boolean pushBack(T newElement) {        Element<T> element = new Element<>();        element.setValue(newElement);        if (size == 0) {            first = element;            size++;            return true;        }        if (last == null) {            last = new Element<>();            last.setValue(newElement);            first.setNext(last);        } else {            last.setNext(element);            last = element;        }        size++;        return true;    }    @Override    public boolean popFront() {        if (size == 0) {            return false;        }        first = first.getNext();        size--;        return true;    }    @Override    public Element<T> front() {        return first;    }    @Override    public int size() {        return size;    }}/** * 队列接口 * Create by zxb on 2017/8/27 */public interface IQueue<R> {    boolean push(R newElement);    boolean pop();    R front();    int size();    boolean display();}/** * 队列实现 * Create by zxb on 2017/8/27 */public class QueueImpl<R> implements IQueue<R> {    private ListImpl<R> list;    @Override    public boolean push(R newElement) {        if (list == null) {            list = new ListImpl<>();        }        list.pushBack(newElement);        return true;    }    @Override    public boolean pop() {        if (list == null) {            list = new ListImpl<>();        }        list.popFront();        return true;    }    @Override    public R front() {        return list.front().getValue();    }    @Override    public int size() {        return list.size();    }    @Override    public boolean display() {        Element<R> front = list.front();        System.out.println("列表元素：");        Element<R> temp = front;        while (temp != null) {            System.out.print(temp.getValue());            temp = temp.getNext();            System.out.println("\t");        }        return true;    }}/** * Create by zxb on 2017/8/27 */public class Test {    public static void main(String[] args) {        IQueue<String> queue = new QueueImpl<>();        queue.push("one");        queue.push("two");        queue.push("three");        queue.pop();        queue.display();    }}

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