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25 
26 package java.nio.file;
27 
28 /**
29  * Defines the standard open options.
30  *
31  * @since 1.7
32  */
33 
34 public enum StandardOpenOption implements OpenOption {
35     /**
36      * Open for read access.
37      */
38     READ,
39 
40     /**
41      * Open for write access.
42      */
43     WRITE,
44 
45     /**
46      * If the file is opened for {@link #WRITE} access then bytes will be written
47      * to the end of the file rather than the beginning.
48      *
49      * <p> If the file is opened for write access by other programs, then it
50      * is file system specific if writing to the end of the file is atomic.
51      */
52     APPEND,
53 
54     /**
55      * If the file already exists and it is opened for {@link #WRITE}
56      * access, then its length is truncated to 0. This option is ignored
57      * if the file is opened only for {@link #READ} access.
58      */
59     TRUNCATE_EXISTING,
60 
61     /**
62      * Create a new file if it does not exist.
63      * This option is ignored if the {@link #CREATE_NEW} option is also set.
64      * The check for the existence of the file and the creation of the file
65      * if it does not exist is atomic with respect to other file system
66      * operations.
67      */
68     CREATE,
69 
70     /**
71      * Create a new file, failing if the file already exists.
72      * The check for the existence of the file and the creation of the file
73      * if it does not exist is atomic with respect to other file system
74      * operations.
75      */
76     CREATE_NEW,
77 
78     /**
79      * Delete on close. When this option is present then the implementation
80      * makes a <em>best effort</em> attempt to delete the file when closed
81      * by the appropriate {@code close} method. If the {@code close} method is
82      * not invoked then a <em>best effort</em> attempt is made to delete the
83      * file when the Java virtual machine terminates (either normally, as
84      * defined by the Java Language Specification, or where possible, abnormally).
85      * This option is primarily intended for use with <em>work files</em> that
86      * are used solely by a single instance of the Java virtual machine. This
87      * option is not recommended for use when opening files that are open
88      * concurrently by other entities. Many of the details as to when and how
89      * the file is deleted are implementation specific and therefore not
90      * specified. In particular, an implementation may be unable to guarantee
91      * that it deletes the expected file when replaced by an attacker while the
92      * file is open. Consequently, security sensitive applications should take
93      * care when using this option.
94      *
95      * <p> For security reasons, this option may imply the {@link
96      * LinkOption#NOFOLLOW_LINKS} option. In other words, if the option is present
97      * when opening an existing file that is a symbolic link then it may fail
98      * (by throwing {@link java.io.IOException}).
99      */
100     DELETE_ON_CLOSE,
101 
102     /**
103      * Sparse file. When used with the {@link #CREATE_NEW} option then this
104      * option provides a <em>hint</em> that the new file will be sparse. The
105      * option is ignored when the file system does not support the creation of
106      * sparse files.
107      */
108     SPARSE,
109 
110     /**
111      * Requires that every update to the file's content or metadata be written
112      * synchronously to the underlying storage device.
113      *
114      * @see <a href="package-summary.html#integrity">Synchronized I/O file integrity</a>
115      */
116     SYNC,
117 
118     /**
119      * Requires that every update to the file's content be written
120      * synchronously to the underlying storage device.
121      *
122      * @see <a href="package-summary.html#integrity">Synchronized I/O file integrity</a>
123      */
124     DSYNC;
125 }
126