双括号初始化理解及效率问题参考：双大括号初始化的理解和使用

package com.idark;

import java.util.ArrayList;

/**
 * @description: Demo测试
 * @author: iDark
 * @create: 2018/8/3 14:57
 * @email: 43352901@qq.com
 */
public class Demo {
    public static void main(String[] args) {

        //Method 1
        ArrayList<String> lists1 = new ArrayList<String>();
        lists1.add("test1");
        lists1.add("test2");

        //Method 2 , (double brace initialization)
        ArrayList<String> lists2 = new ArrayList<String>(){{
            add("test1");
            add("test2");
        }};
    }
}