java - 使用Arraylist的2D数组表示

Question

我想实现数据的2D表示，其中每一行代表高斯分布的要素。我做了以下事情：

     public ArrayList<ArrayList<Double>> getFeature( BufferedReader buffer1)

  {   ArrayList<Double> arrList1 = new ArrayList<Double>();
    ArrayList<ArrayList<Double>> arrList2 = new ArrayList<ArrayList<Double>>();
    String[] strArr = getWords(buff1); 
    for(int j=0 ; j< strArr.length; j++){
    for(int i =0 ;i < 50 ; i++){
        arrList1.add(rand.nextGaussian());
    }
    arrList2.add(arrList1);
    }
    System.out.println("size of arrList2:"+ arrList2.size());       
    System.out.println(arrList2.toArray()[0]);
    System.out.println(arrList2.toArray()[1]);
    return arrList2;
}

当我进行编译并想要获取每一行的值时，我会得到奇怪的输出。有人可以告诉我原因吗？

预期的输出是：

  System.out.println(arrList2.toArray()[0]);

 [0.08,1.1 .............,0.98]

尺寸为50的数组，上面填充了上述值。

以下是奇怪的输出。太大了

[0.46462618324716254，-0.7461971643031985，0.11198107553318244，-0.5445576195764561，-0.09170153174710902，1.0599085675813804，-0.5121868425685772，0.6578194527724543，0.07180836719554716，-0.8711795090831688，-1.1685999674955914，-0.8467566589850426，-0.9464559617558149，-0.25455126102711567，0.6880497852836619，0.05802417861623583，0.7605219159096197，0.5573206594413265，-0.6464485036951102，0.9928577372480463 ，0.769468353755745，-1.0349221359588956，1.7475686681406222，0.7286721770852165，1.1938115793074722，0.05051321258899094，-1.5274223735062666，-0.10652710930319426，-2.1566969444968622，1.4572264331572156，-0.07630289414615696，0.2776127747056551，-0.3009457462994894，0.9554273666202241，-2.1190393953455047，0.4580572585843065，-0.6413109094169921，-0.4978755907488374，0.353842909950826，-1.257672808328245 ，-0.3236234929243931，-0.8899339209743886，0.347442395255124，-0.48611580230648704，1.219007569267497，-1.1789975566918134，-0.01825901882420379，-1.6486718275722763，-0.3819 056170192554，0.6042625214995715，0.33415986866928，-0.07450314651627132，1.1181610738837455，-0.44555621990204264，2.2166172691235473，-0.6944430028545253，1.7804248652436612，-0.3801297513557677，0.1603379135566103，0.4370378823762644，0.6537078245920281，-0.5909651262165042，-0.09079544840341715，-0.4588221391142408，0.3191257940850721，0.851481629251832，1.5836138371905788，-0.9214851789009444，-0.40274669796854634 ，0.33137905198405093、0.22048511721877453，-1.6107690385201552，-2.2293481002062734，-1.5862880920203761，-3.021081392986815、0.4806258491486294，-1.4404361309735374，-0.11292399203207835，-1.3927949945851505，-0.999380367686273，-0.34942295版的背景信息为： -0.5673683910852766、0.4350772179247941，-2.310707468789298，-1.3594784507734978，-0.420522194159102、0.8723173566610757、0.08704331777378478、0.19156519877684638、1.13490819832362、2.26583242405553 7，0.08824246678795156，1.3416771872818614，2.0113403780125716，-0.6591827547030255，-2.1221005234426045，0.22388389358930083，-0.35281199160944976，1.57513125025632，-0.5543596830360817，0.24276349413614184，-0.6933647399153053，2.1733561712603406，-1.1295984403806556，0.978199373546278，1.4765841816237413，-0.23614652784978474，0.6860841664188477，1.724839793220621，0.09890307698728121，1.1759901942152857， - 0.11367559429189428，0.03751374982321288，-0.706440448714537，1.1162223672467126，0.029899521729224297，-1.0524377764950592，-1.272575346202225，0.05911556504138499，2.5567151468399905，-0.0876438255791631，0.7405000550984376，-0.4653784955900584，1.0347442227437538，-0.7400874338357808，-1.9149762503590055，-0.23253357169676564，-0.027095878580104853，1.3433163962194588，0.6380374697876411，0.239540766344537，0.15521652189382637 ，1.6840845846495722，-1.2654453459207138，-0.37480522158157953，-0.35072194870832607，-0.13003189765184803，-0.3777510145240076，1.7368696932480285，1.59 6933980850992，0.8903554445814371，1.5595823556184982，-1.6215290944712​​14，-1.1200493175424486，-0.40963276102036，0.616137661053976，0.21520038251543913，-0.10766640285845859，-2.3431682923959283，0.8376474132653909，-1.624204670319171，-1.53​​39135491664488，0.5745962643679627，-1.8672864673583596，0.5893904049046332，1.6101909333097806，1.4942863128478316，0.4393934760020643，0.4543320364876582，-2.1477119468636756 ，-0.8675089134938178，-1.304347506660454，0.265582855165904，-0.43315684866326326853，1.396958388154523，-0.0366978863358013，0.7573031920372403，-0.3082978848734662，-1.3293560483520508，-0.014314267765796158，0.9963287565650347，0.4441330376836758,1.1685694 0.5793543872028564，-0.7709908841891148，-0.2752441993676809、1.0127096639099775、0.7928535829487908、0.7274343974269051，-0.3572327111704678，-0.3635339942400348，-1.5135817949705679，-0.8096606039385091， -2.028809935367818，-0.2383975926640008、0.9888240231357164，-0.46822533717671233、0.12555572481497712、0.9249518473038246，-0.7696485018788267、0.7104271113662229、0.462549756020218、0.4661108737616203，-1.3393695430612715、1.3127387014622函件-208.1160345161616161616161616161616608608 / 1603.6654613 1.55129717824011，-0.0068777633683922285，1.3326516059681166， - 0.36987435658432716，-0.23254064940739874，0.4093041605249441，-0.22152432261151883，0.11956045271155907，0.817312179186691，-1.109714930373252，1.6919073761823942，-2.477322936459778，-0.8041619336754456，0.5354776432522204，-1.3994286642549634，0.7621208634646848，0.3168358861977863，0.5654315361895403，0.19188988525917902，-1.8959135432065441， - 0.8883163800042816，-0.07396400493233038，-1.811056975930386、0.8323666750629728、0.16495843660377815、0.9180073204622988，-0.18482724669045245，-0.926597451803997，-0.37373162068547583、1.2784 981694766253，-0.9622089382124651，0.36846446000890226，1.7781522414929132，0.22598541140652853，0.0698645511906671，0.32437679311726797，-1.2473606786833797，-0.4098009718556575，0.04826245169132581，0.7412730519089504，-0.2550533401514563，-0.16038376756843503，-1.7248853346384536，-0.9996464058972109，-0.6041936215771648，0.7012791176135328，0.2634365350229634，1.6681642878727803，0.5006091547003853，0.8625317708776815， 0.1915138247321982，0.2611860227007197，1.1701209557262373，0.9057134706410637，-1.7953870540423091，1.2544035731509018，-0.8592198056076387，-0.7480509518320575，-1.4509156168191215，-0.6256261144134664，-0.3991019440510313，0.665093736894838，0.8193871205290613，0.3194454906105449，-0.7766590102568899，-0.4368566309637124，-0.5917671696216537，0.8311430693910862，-0.03873251937784431，0.12352685387320661， -1.3032763393594495，-1.3089664655879443，1.0600394162534208，-1.0448890523458283，0.06485611850874347，0.9952192969393494，0.7564433698789398，-0.129343789502656 82，-2.455965368428643，0.32562880194284605，1.0608150376407195，-0.5856546412601992，0.04459245589226094，-1.0485199770272802，0.171758532083598，-0.15219755725779346，0.22588623160615964，-0.8866303888277965，0.18071263060711168，-0.8101056664306856，0.40109990179114574，-1.2052661486349423，-0.7063493195672804，0.3790905532531173，0.6187801708754183，0.8973661967856524，-0.5094785611904082， - 0.3121531241358417，-1.504997213561154，-0.29555598943521805，1.0177433955336386，0.6339433797662462，1.2314472398672958，0.49767372261246906，-0.8671596473555494，0.020938436521665212，1.0742606122969818，0.2084859973134108，0.4575308821288143，-0.535411744646708，-0.24438736749632228，-0.3011498246747746，1.157476461518601，0.5710113681137887，-0.373272138340946，0.20493086120987056，1.123285194699328，-0.6825221360843674， -0.4970861054585663、0.7031584488452262，-1.0087051135013718、0.4868567370256535，-1.5746589820932297、0.6644556691032865，-1.7412055461143485、0.12967849664472705、0.998921 4649538823，-0.8765814845104847，-0.31879367165788586，-0.017003683057253013，0.05430609428313103，1.1269963542976742，0.5736040532976195，0.1496540697620177，0.06763527054881197，-1.50267130541346，-1.5429648962225846，2.2174812208256647，0.2823275216048955，-2.2106774000464493，-0.750663549795398，-0.9811875317052499，-2.2030641858374813，0.3394153119839848，0.8801000780568257，0.019408804996847228，0.08061006725110524 ，-0.7724864191394777，-0.09482684057846079，-0.7973308945882334，-0.004422694306238711，1.2373993506699386，-0.7465724077874447，1.0594472039581748，-1.2008095220092798，0.8786821374927449，0.5443643385981153，-1.1168872095026448，0.35057545786785094，1.177175145035326，0.8429246083369465，-0.689723978576773，0.502354026275667，-0.04613819184631698，-0.31654699432372757，1.5637862738408093， - 0.5878311289195507，-1.108863150121421，-0.9675335342352381，-1.5636914224520626、0.5945700685544679、0.442348543851493，-0.5701784046610815，-1.0845765562612784，-0.08278380885541 176，-0.8583670878589341，-1.4720479343149773，2.476311343964019，0.41098252758504555，-0.5657085013332471，-0.4747296304703354，1.006084355270273，0.25723416685361056，-0.6984274306212112，0.4377896208622477，0.6460870382990315，1.3950158568304747，-0.3624333355923981，0.7986730261282601，0.36392864932106034，0.023479591985569596，-2.3188641866554884，0.5246979591766888，-2.1052930104185146，-0.22436539681910755 ，-2.3632802785522316、0.2404756864360818，-0.42347922227477375，-0.649171984257037，-0.2663913129281969，-0.2736238409904541，0.6799926243706352，-1.8905581628639156，-0.48729302618445974，0.1364732249240771，-0.654681523885463，-0.09333650364679 6790.5654679 ，0.08286272472028665，-1.2802662861780678，1.0188894812147609，0.9180346491197053，-0.19780005867554104，-1.7225586291221011，-0.9666520007701466，0.6167702134637302，-2.0062593053447033，-0.027871345689201 08，-1.3083998368624299，2.028363730323775，1.0735441642956547，-1.9121778665959235，-1.2004021402148826，0.09209714265736849，0.9735003811225864，0.5740061725879747，0.010155866002321106，-0.5414073891346262，-0.3026220001630864，-0.3253578888041597，1.467401121778751，-0.4019227651608376，0.9926598684708873，-0.5797202651954227，-0.6032027120399337，-1.5790046534628106，-0.29285533369483696 ，-0.22908084437071766，-2.7547034239754704，-0.567678718427886，-0.11729223172989703，-0.9062509770861983，1.1423026021495064，-0.9592198901154894，0.5837287865704088，2.3534533038037786，1.3643136287060391，-0.4191819646187235，-0.5815374294761 617 0.18934519706740402，-1.4654238839941143、1.3940899668780722、1.9999287460039069、0.5593145516942836、0.41146316021623797、0.7980232784956701、0.4331041949731728、0.9824211191778849，-0.49718888243359466、0.26470386540283247、0.9 574507682361967，-0.874516288215613，-1.9849619724051226，-0.558877120925908，-0.5071314855164495，-0.7956992895178723，-1.2616310109098234，-0.6810345434093048，-1.3306339462185115，-0.6894885013031004，-0.7110844934740447，1.0976801504552224 0.03230440501913142、0.5592484434095385，-1.0240995675521865、1.921011636618146，-1.8425494238779783、0.5371478992314899、0.1177459062388671，-0.1696263342284998、0.35215096349316727，-0.024862173384408784，-0

Answer 1

您需要在外循环的每次迭代中重新初始化arrList1：

for(int j = 0; j < strArr.length; j++){
    arrList1 = new ArrayList<Double>();
    for(int i = 0; i < 50; i++){
       arrList1.add(rand.nextGaussian());
    }
    arrList2.add(arrList1);
}

否则，您将继续添加相同的ArrayList，这就是获得大量输出的原因。