Javaの - ファイルを解析するためにアレイとStreamsを使用して、右の項目を取得していません

その他 2022-04-22 10:33:53 訪問数: 0
PacificNW_Lover：

Javaの1.8のストリーム機能を使用して、MacOSのモハーベ10.14.3オペレーティングシステム上の/ etc / groupファイルを解析しようとしています。

次のように私の/ etc / groupファイル内の行のフルセットは、以下のとおりです。

nobody:*:-2:
nogroup:*:-1:
wheel:*:0:root
daemon:*:1:root
kmem:*:2:root
sys:*:3:root
tty:*:4:root
operator:*:5:root
mail:*:6:_teamsserver
bin:*:7:
procview:*:8:root
procmod:*:9:root
owner:*:10:
everyone:*:12:
_taskgated:*:13:_taskgated
group:*:16:
staff:*:20:root
_networkd:*:24:
_installassistant:*:25:
_lp:*:26:
_postfix:*:27:
_postdrop:*:28:
certusers:*:29:root,_jabber,_postfix,_cyrus,_calendar,_dovecot
_keytabusers:*:30:_calendar,_jabber,_postfix
_scsd:*:31:
_ces:*:32:
_appstore:*:33:_appstore
utmp:*:45:
authedusers:*:50:
interactusers:*:51:
netusers:*:52:
consoleusers:*:53:
_mcxalr:*:54:
_appleevents:*:55:
_geod:*:56:
_devdocs:*:59:
_sandbox:*:60:
localaccounts:*:61:
netaccounts:*:62:
_mdnsresponder:*:65:
_uucp:*:66:
_ard:*:67:
dialer:*:68:
network:*:69:
_www:*:70:_devicemgr,_teamsserver
_eppc:*:71:_eppc
_cvs:*:72:
_svn:*:73:
_mysql:*:74:
_sshd:*:75:
_qtss:*:76:
_mailman:*:78:
_appserverusr:*:79:
admin:*:80:root
_appserveradm:*:81:
_clamav:*:82:
_amavisd:*:83:
_jabber:*:84:
_appowner:*:87:
_windowserver:*:88:
_spotlight:*:89:
accessibility:*:90:
_tokend:*:91:
_securityagent:*:92:
_calendar:*:93:_teamsserver
_teamsserver:*:94:_devicemgr
_update_sharing:*:95:
_installer:*:96:
_atsserver:*:97:
_lpadmin:*:98:
_unknown:*:99:
_lpoperator:*:100:
_softwareupdate:*:200:_softwareupdate
_guest:*:201:
_coreaudiod:*:202:
_screensaver:*:203:
_developer:*:204:
_locationd:*:205:
_detachedsig:*:207:_locationd
_trustevaluationagent:*:208:
_odchpass:*:209:_teamsserver
_timezone:*:210:
_lda:*:211:
_cvms:*:212:
_usbmuxd:*:213:
_postgres:*:216:_devicemgr,_calendar,_teamsserver,_xserverdocs
_devicemgr:*:220:
_webauthserver:*:221:_teamsserver,_devicemgr
_netbios:*:222:
_warmd:*:224:_warmd
_dovenull:*:227:
_netstatistics:*:228:
_assetcache:*:235:
_coremediaiod:*:236:
_launchservicesd:*:239:
_iconservices:*:240:
_distnote:*:241:
_nsurlsessiond:*:242:
_nsurlstoraged:*:243:
_displaypolicyd:*:244:
_astris:*:245:
_gamecontrollerd:*:247:
_mbsetupuser:*:248:
_ondemand:*:249:
_analyticsusers:*:250:_analyticsd,_networkd,_timed,_reportmemoryexception
_xserverdocs:*:251:
_wwwproxy:*:252:
_mobileasset:*:253:
_findmydevice:*:254:
_datadetectors:*:257:
_captiveagent:*:258:
_ctkd:*:259:
_applepay:*:260:
_hidd:*:261:
_cmiodalassistants:*:262:
_analyticsd:*:263:_analyticsd
_webdeveloper:*:264:
_fpsd:*:265:_fpsd
_timed:*:266:
_reportmemoryexception:*:269:_reportmemoryexception
com.apple.access_ftp:*:395:
com.apple.access_disabled:*:396:
com.apple.access_sessionkey:*:397:
com.apple.access_screensharing:*:398:
com.apple.access_ssh:*:399:

Group.java：

public class Group {
    private String gid;
    private String name;
    private String members;

    public Group(String line) {
        String[] items = line.split(":");

        if (items.length <= 3) {
            this.name = items[0];
            System.out.print("Name: " + name + ", ");
            this.gid = items[2];
            System.out.print(" gid: " + gid + ", ");
        }
        else if (items.length >=3 || this.name != null || "".equals(this.name)){
            this.members = items[3];
            System.out.println("Members: " + members);
        }
    }

    // Omitted getters & setters for brevity

}

このGroupsParserを作成しました：

public class GroupParser {

    public static List<Group> getAllGroups(String line) {
        List<Group> groups = null;
        try (Stream<String> stream = Files.lines(Paths.get(line))) {

            groups = stream.filter(s -> s.charAt(0) != '#').map(Group::new)
                     .collect(Collectors.toCollection(ArrayList::new));
        } 
        catch (Exception e) {
            e.printStackTrace();
        }
        return groups;
    }

    public static void main(String[] args) {
        List<Group> groups = GroupParser.getAllGroups("/etc/group");
        for (Group group : groups) {
            System.out.println("Group: " + group.getName() + ", gid: " + group.getGid() + ", members: " + group.getMembers());
        }
    }
}

（順不同で明らかであり、いくつかのアイテムが欠けて）次の出力を受信：

Group: nobody, gid: -2, members: null
Group: nogroup, gid: -1, members: null
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: _teamsserver
Group: bin, gid: 7, members: null
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: owner, gid: 10, members: null
Group: everyone, gid: 12, members: null
Group: null, gid: null, members: _taskgated
Group: group, gid: 16, members: null
Group: null, gid: null, members: root
Group: _networkd, gid: 24, members: null
Group: _installassistant, gid: 25, members: null
Group: _lp, gid: 26, members: null
Group: _postfix, gid: 27, members: null
Group: _postdrop, gid: 28, members: null
Group: null, gid: null, members: root,_jabber,_postfix,_cyrus,_calendar,_dovecot
Group: null, gid: null, members: _calendar,_jabber,_postfix
Group: _scsd, gid: 31, members: null
Group: _ces, gid: 32, members: null
Group: null, gid: null, members: _appstore
Group: utmp, gid: 45, members: null
Group: authedusers, gid: 50, members: null
Group: interactusers, gid: 51, members: null
Group: netusers, gid: 52, members: null
Group: consoleusers, gid: 53, members: null
Group: _mcxalr, gid: 54, members: null
Group: _appleevents, gid: 55, members: null
Group: _geod, gid: 56, members: null
Group: _devdocs, gid: 59, members: null
Group: _sandbox, gid: 60, members: null
Group: localaccounts, gid: 61, members: null
Group: netaccounts, gid: 62, members: null
Group: _mdnsresponder, gid: 65, members: null
Group: _uucp, gid: 66, members: null
Group: _ard, gid: 67, members: null
Group: dialer, gid: 68, members: null
Group: network, gid: 69, members: null
Group: null, gid: null, members: _devicemgr,_teamsserver
Group: null, gid: null, members: _eppc
Group: _cvs, gid: 72, members: null
Group: _svn, gid: 73, members: null
Group: _mysql, gid: 74, members: null
Group: _sshd, gid: 75, members: null
Group: _qtss, gid: 76, members: null
Group: _mailman, gid: 78, members: null
Group: _appserverusr, gid: 79, members: null
Group: null, gid: null, members: root
Group: _appserveradm, gid: 81, members: null
Group: _clamav, gid: 82, members: null
Group: _amavisd, gid: 83, members: null
Group: _jabber, gid: 84, members: null
Group: _appowner, gid: 87, members: null
Group: _windowserver, gid: 88, members: null
Group: _spotlight, gid: 89, members: null
Group: accessibility, gid: 90, members: null
Group: _tokend, gid: 91, members: null
Group: _securityagent, gid: 92, members: null
Group: null, gid: null, members: _teamsserver
Group: null, gid: null, members: _devicemgr
Group: _update_sharing, gid: 95, members: null
Group: _installer, gid: 96, members: null
Group: _atsserver, gid: 97, members: null
Group: _lpadmin, gid: 98, members: null
Group: _unknown, gid: 99, members: null
Group: _lpoperator, gid: 100, members: null
Group: null, gid: null, members: _softwareupdate
Group: _guest, gid: 201, members: null
Group: _coreaudiod, gid: 202, members: null
Group: _screensaver, gid: 203, members: null
Group: _developer, gid: 204, members: null
Group: _locationd, gid: 205, members: null
Group: null, gid: null, members: _locationd
Group: _trustevaluationagent, gid: 208, members: null
Group: null, gid: null, members: _teamsserver
Group: _timezone, gid: 210, members: null
Group: _lda, gid: 211, members: null
Group: _cvms, gid: 212, members: null
Group: _usbmuxd, gid: 213, members: null
Group: null, gid: null, members: _devicemgr,_calendar,_teamsserver,_xserverdocs
Group: _devicemgr, gid: 220, members: null
Group: null, gid: null, members: _teamsserver,_devicemgr
Group: _netbios, gid: 222, members: null
Group: null, gid: null, members: _warmd
Group: _dovenull, gid: 227, members: null
Group: _netstatistics, gid: 228, members: null
Group: _assetcache, gid: 235, members: null
Group: _coremediaiod, gid: 236, members: null
Group: _launchservicesd, gid: 239, members: null
Group: _iconservices, gid: 240, members: null
Group: _distnote, gid: 241, members: null
Group: _nsurlsessiond, gid: 242, members: null
Group: _nsurlstoraged, gid: 243, members: null
Group: _displaypolicyd, gid: 244, members: null
Group: _astris, gid: 245, members: null
Group: _gamecontrollerd, gid: 247, members: null
Group: _mbsetupuser, gid: 248, members: null
Group: _ondemand, gid: 249, members: null
Group: null, gid: null, members: _analyticsd,_networkd,_timed,_reportmemoryexception
Group: _xserverdocs, gid: 251, members: null
Group: _wwwproxy, gid: 252, members: null
Group: _mobileasset, gid: 253, members: null
Group: _findmydevice, gid: 254, members: null
Group: _datadetectors, gid: 257, members: null
Group: _captiveagent, gid: 258, members: null
Group: _ctkd, gid: 259, members: null
Group: _applepay, gid: 260, members: null
Group: _hidd, gid: 261, members: null
Group: _cmiodalassistants, gid: 262, members: null
Group: null, gid: null, members: _analyticsd
Group: _webdeveloper, gid: 264, members: null
Group: null, gid: null, members: _fpsd
Group: _timed, gid: 266, members: null
Group: null, gid: null, members: _reportmemoryexception
Group: com.apple.access_ftp, gid: 395, members: null
Group: com.apple.access_disabled, gid: 396, members: null
Group: com.apple.access_sessionkey, gid: 397, members: null
Group: com.apple.access_screensharing, gid: 398, members: null
Group: com.apple.access_ssh, gid: 399, members: null
Group: nobody, gid: -2, members: null
Group: nogroup, gid: -1, members: null
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: null, gid: null, members: _teamsserver
Group: bin, gid: 7, members: null
Group: null, gid: null, members: root
Group: null, gid: null, members: root
Group: owner, gid: 10, members: null
Group: everyone, gid: 12, members: null
Group: null, gid: null, members: _taskgated
Group: group, gid: 16, members: null
Group: null, gid: null, members: root
Group: _networkd, gid: 24, members: null
Group: _installassistant, gid: 25, members: null
Group: _lp, gid: 26, members: null
Group: _postfix, gid: 27, members: null
Group: _postdrop, gid: 28, members: null
Group: null, gid: null, members: root,_jabber,_postfix,_cyrus,_calendar,_dovecot
Group: null, gid: null, members: _calendar,_jabber,_postfix
Group: _scsd, gid: 31, members: null
Group: _ces, gid: 32, members: null
Group: null, gid: null, members: _appstore
Group: utmp, gid: 45, members: null
Group: authedusers, gid: 50, members: null
Group: interactusers, gid: 51, members: null
Group: netusers, gid: 52, members: null
Group: consoleusers, gid: 53, members: null
Group: _mcxalr, gid: 54, members: null
Group: _appleevents, gid: 55, members: null
Group: _geod, gid: 56, members: null
Group: _devdocs, gid: 59, members: null
Group: _sandbox, gid: 60, members: null
Group: localaccounts, gid: 61, members: null
Group: netaccounts, gid: 62, members: null
Group: _mdnsresponder, gid: 65, members: null
Group: _uucp, gid: 66, members: null
Group: _ard, gid: 67, members: null
Group: dialer, gid: 68, members: null
Group: network, gid: 69, members: null
Group: null, gid: null, members: _devicemgr,_teamsserver
Group: null, gid: null, members: _eppc
Group: _cvs, gid: 72, members: null
Group: _svn, gid: 73, members: null
Group: _mysql, gid: 74, members: null
Group: _sshd, gid: 75, members: null
Group: _qtss, gid: 76, members: null
Group: _mailman, gid: 78, members: null
Group: _appserverusr, gid: 79, members: null
Group: null, gid: null, members: root
Group: _appserveradm, gid: 81, members: null
Group: _clamav, gid: 82, members: null
Group: _amavisd, gid: 83, members: null
Group: _jabber, gid: 84, members: null
Group: _appowner, gid: 87, members: null
Group: _windowserver, gid: 88, members: null
Group: _spotlight, gid: 89, members: null
Group: accessibility, gid: 90, members: null
Group: _tokend, gid: 91, members: null
Group: _securityagent, gid: 92, members: null
Group: null, gid: null, members: _teamsserver
Group: null, gid: null, members: _devicemgr
Group: _update_sharing, gid: 95, members: null
Group: _installer, gid: 96, members: null
Group: _atsserver, gid: 97, members: null
Group: _lpadmin, gid: 98, members: null
Group: _unknown, gid: 99, members: null
Group: _lpoperator, gid: 100, members: null
Group: null, gid: null, members: _softwareupdate
Group: _guest, gid: 201, members: null
Group: _coreaudiod, gid: 202, members: null
Group: _screensaver, gid: 203, members: null
Group: _developer, gid: 204, members: null
Group: _locationd, gid: 205, members: null
Group: null, gid: null, members: _locationd
Group: _trustevaluationagent, gid: 208, members: null
Group: null, gid: null, members: _teamsserver
Group: _timezone, gid: 210, members: null
Group: _lda, gid: 211, members: null
Group: _cvms, gid: 212, members: null
Group: _usbmuxd, gid: 213, members: null
Group: null, gid: null, members: _devicemgr,_calendar,_teamsserver,_xserverdocs
Group: _devicemgr, gid: 220, members: null
Group: null, gid: null, members: _teamsserver,_devicemgr
Group: _netbios, gid: 222, members: null
Group: null, gid: null, members: _warmd
Group: _dovenull, gid: 227, members: null
Group: _netstatistics, gid: 228, members: null
Group: _assetcache, gid: 235, members: null
Group: _coremediaiod, gid: 236, members: null
Group: _launchservicesd, gid: 239, members: null
Group: _iconservices, gid: 240, members: null
Group: _distnote, gid: 241, members: null
Group: _nsurlsessiond, gid: 242, members: null
Group: _nsurlstoraged, gid: 243, members: null
Group: _displaypolicyd, gid: 244, members: null
Group: _astris, gid: 245, members: null
Group: _gamecontrollerd, gid: 247, members: null
Group: _mbsetupuser, gid: 248, members: null
Group: _ondemand, gid: 249, members: null
Group: null, gid: null, members: _analyticsd,_networkd,_timed,_reportmemoryexception
Group: _xserverdocs, gid: 251, members: null
Group: _wwwproxy, gid: 252, members: null
Group: _mobileasset, gid: 253, members: null
Group: _findmydevice, gid: 254, members: null
Group: _datadetectors, gid: 257, members: null
Group: _captiveagent, gid: 258, members: null
Group: _ctkd, gid: 259, members: null
Group: _applepay, gid: 260, members: null
Group: _hidd, gid: 261, members: null
Group: _cmiodalassistants, gid: 262, members: null
Group: null, gid: null, members: _analyticsd
Group: _webdeveloper, gid: 264, members: null
Group: null, gid: null, members: _fpsd
Group: _timed, gid: 266, members: null
Group: null, gid: null, members: _reportmemoryexception
Group: com.apple.access_ftp, gid: 395, members: null
Group: com.apple.access_disabled, gid: 396, members: null
Group: com.apple.access_sessionkey, gid: 397, members: null
Group: com.apple.access_screensharing, gid: 398, members: null
Group: com.apple.access_ssh, gid: 399, members: null

質問（秒）：

  1. この出力は、注文していないようです

    グループ：誰も、GID：-2、メンバー：ヌル

    グループ：nogroupが、GID：-1、メンバー：ヌル

なぜ私はnogroupがとホイールの間に、これを取得していますか？

  1. これらの項目を抽出するための良い方法はありますか？なぜ私はkmemのか、ホイールのどこを見ることができませんか？

  2. ストリーム経由でこれを修正/確認する方法はありますか？

また：

あなたにマッピングで使用しているコンストラクタでは問題の嘘のコア.map(Group::new)。現在実装コンストラクタのロジックが発生するいくつかの質問の理由です。どのように下に説明しようとします：

public Group(String line) {
    String[] items = line.split(":"); // you split up the string into contents based on ':' separator

内容は以下に分割されているか、3部に等しいかどうかを確認するための条件では、あなたはまた、配列のサイズは、少なくともであろうと、ここで前提作った3やったときにアクセスするつもり何であるが、items[2]。お知らせけれども、items.lengthは2されている可能性があれば、if条件は成功しますが、それでもこの種のアクセスのためのAIOOBEを取得してしまうために許可されているだろう。

    if (items.length <= 3) {
        this.name = items[0];
        System.out.print("Name: " + name + ", ");
        this.gid = items[2];
        System.out.print(" gid: " + gid + ", ");
    }

文字列の内容は、3つの以上の部分に分割することができたとき、あなたは初期化しない傾向があるname、gidそのためにGroup、したがって、あなたがそれらの持っているnullあなたの出力で秒。

    else {

        this.members = items[3];
        System.out.println("Members: " + members);
    }
}

これらの項目を抽出するための良い方法はありますか？なぜ私はkmemのか、ホイールのどこを見ることができませんか？

取り扱いに関連するセクションnullにそれらを初期化することによって値はそれを解決しているだろう。

うまくとしてNPEを回避するには、初期化したい場合がありますgroups空のリストに、

List<Group> groups = new ArrayList<>();

分割が使用している場合、文字列は、常に3つの以上の構成要素を持っているという仮定に基づいて単純な実装では、:次のようになります。

public Group(String line) {
    String[] items = line.split(":");
    this.name = items[0];
    this.gid = Integer.parseInt(items[2]);
    if (items.length > 3){
        this.members = items[3];
    }
}

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