Java获取字符串里面的重复字符

public static void main(String[] args) {
        String word="天地玄黄宇宙洪荒" + 

                "日月盈昃辰宿列张" + 

                "寒来暑往秋收冬藏" + 

                "闰余成岁律吕调阳" + 

                "云腾致雨露结为霜" + 

                "金生丽水玉出昆冈" + 

                "剑号巨阙珠称夜光" + 

                "果珍李柰菜重芥姜" + 

                "海咸河淡鳞潜羽翔" + 

                "龙师火帝鸟官人皇" + 

                "始制文字乃服衣裳" + 

                "推位让国有虞陶唐" + 

                "吊民伐罪周发殷汤" + 

                "坐朝问道垂拱平章" + 

                "爱育黎首臣伏戎羌" + 

                "遐迩一体率宾归王" + 

                "鸣凤在竹白驹食场" + 

                "化被草木赖及万方" + 

                "盖此身发四大五常" + 

                "恭惟鞠养岂敢毁伤" + 

                "女慕贞洁男效才良" + 

                "知过必改得能莫忘" + 

                "罔谈彼短靡恃己长" + 

                "信使可覆器欲难量" + 

                "墨悲丝染诗赞羔羊" + 

                "景行维贤克念作圣" + 

                "德建名立形端表正" + 

                "空谷传声虚堂习听" + 

                "祸因恶积福缘善庆" + 

                "尺璧非宝寸阴是竞" + 

                "资父事君曰严与敬" + 

                "孝当竭力忠则尽命" + 

                "临深履薄夙兴温凊" + 

                "似兰斯馨如松之盛" + 

                "川流不息渊澄取映" + 

                "容止若思言辞安定" + 

                "笃初诚美慎终宜令" + 

                "荣业所基籍甚无竟" + 

                "学优登仕摄职从政" + 

                "存以甘棠去而益咏" + 

                "乐殊贵贱礼别尊卑" + 

                "上和下睦夫唱妇随" + 

                "外受傅训入奉母仪" + 

                "诸姑伯叔犹子比儿" + 

                "孔怀兄弟同气连枝" + 

                "交友投分切磨箴规" + 

                "仁慈隐恻造次弗离" + 

                "节义廉退颠沛匪亏" + 

                "性静情逸心动神疲" + 

                "守真志满逐物意移" + 

                "坚持雅操好爵自縻" + 

                "都邑华夏东西二京" + 

                "背邙面洛浮渭据泾" + 

                "宫殿盘郁楼观飞惊" + 

                "图写禽兽画彩仙灵" + 

                "丙舍旁启甲帐对楹" + 

                "肆筵设席鼓瑟吹笙" + 

                "升阶纳陛弁转疑星" + 

                "右通广内左达承明" + 

                "既集坟典亦聚群英" + 

                "杜稿钟隶漆书壁经" + 

                "府罗将相路侠槐卿" + 

                "户封八县家给千兵" + 

                "高冠陪辇驱毂振缨" + 

                "世禄侈富车驾肥轻" + 

                "策功茂实勒碑刻铭" + 

                "盘溪伊尹佐时阿衡" + 

                "奄宅曲阜微旦孰营" + 

                "桓公匡合济弱扶倾" + 

                "绮回汉惠说感武丁" + 

                "俊义密勿多士实宁" + 

                "晋楚更霸赵魏困横" + 

                "假途灭虢践土会盟" + 

                "何遵约法韩弊烦刑" + 

                "起翦颇牧用军最精" + 

                "宣威沙漠驰誉丹青" + 

                "九州禹迹百郡秦并" + 

                "岳宗泰岱禅主云亭" + 

                "雁门紫塞鸡田赤诚" + 

                "昆池碣石钜野洞庭" + 

                "旷远绵邈岩岫杳冥" + 

                "治本于农务兹稼穑" + 

                "俶载南亩我艺黍稷" + 

                "税熟贡新劝赏黜陟" + 

                "孟轲敦素史鱼秉直" + 

                "庶几中庸劳谦谨敕" + 

                "聆音察理鉴貌辨色" + 

                "贻厥嘉猷勉其祗植" + 

                "省躬讥诫宠增抗极" + 

                "殆辱近耻林皋幸即" + 

                "两疏见机解组谁逼" + 

                "索居闲处沉默寂寥" + 

                "求古寻论散虑逍遥" + 

                "欣奏累遣戚谢欢招" + 

                "渠荷的历园莽抽条" + 

                "枇杷晚翠梧桐蚤凋" + 

                "陈根委翳落叶飘摇" + 

                "游鹍独运凌摩绛霄" + 

                "耽读玩市寓目囊箱" + 

                "易輶攸畏属耳垣墙" + 

                "具膳餐饭适口充肠" + 

                "饱饫烹宰饥厌糟糠" + 

                "亲戚故旧老少异粮" + 

                "妾御绩纺侍巾帷房" + 

                "纨扇圆洁银烛炜煌" + 

                "昼眠夕寐蓝笋象床" + 

                "弦歌酒宴接杯举殇" + 

                "矫手顿足悦豫且康" + 

                "嫡后嗣续祭祀烝尝" + 

                "稽颡再拜悚惧恐惶" + 

                "笺牒简要顾答审详" + 

                "骸垢想浴执热愿凉" + 

                "驴骡犊特骇跃超骧" + 

                "诛斩贼盗捕获叛亡" + 

                "布射僚丸嵇琴阮箫" + 

                "恬笔伦纸钧巧任钓" + 

                "释纷利俗并皆佳妙" + 

                "毛施淑姿工颦妍笑" + 

                "年矢每催曦晖朗曜" + 

                "璇玑悬斡晦魄环照" + 

                "指薪修祜永绥吉劭" + 

                "矩步引领俯仰廊庙" + 

                "束带矜庄徘徊瞻眺" + 

                "孤陋寡闻愚蒙等诮" + 

                "谓语助者焉哉乎也" ;

        char[] ch1 = word.toCharArray();
        List<Character> list = new ArrayList<>();

        for(char ch : ch1) {
            if (list.contains(ch)) {
                System.out.println(ch);
                list.clear();
            }
            list.add(ch);
            //System.out.println(ch);
        }
        System.out.println(ch1.length);
    }