设计模式

懒汉式单例

public class RecommendPresenter {

    private RecommendPresenter() {
    }

    private static RecommendPresenter sInstance = null;

    /**
     * 获取单例对象
     * @return
     */
    public static RecommendPresenter getInstance() {
        if (sInstance == null) {
            synchronized (RecommendPresenter.class) {
                if (sInstance == null) {
                    sInstance = new RecommendPresenter();
                }
            }
        }
    }
}