917 * last modified.
918 *
919 * <p> Where it is required to distinguish an I/O exception from the case
920 * where {@code 0L} is returned, or where several attributes of the
921 * same file are required at the same time, or where the time of last
922 * access or the creation time are required, then the {@link
923 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
924 * Files.readAttributes} method may be used.
925 *
926 * @apiNote
927 * While the unit of time of the return value is milliseconds,
928 * the granularity of the value depends on the underlying
929 * file system and may be larger. For example, some
930 * file systems use time stamps in units of seconds.
931 *
932 * @return A <code>long</code> value representing the time the file was
933 * last modified, measured in milliseconds since the epoch
934 * (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the
935 * file does not exist or if an I/O error occurs; the value may
936 * be negative in which case its absolute value indicates the
937 * number of milliseconds before the epoch
938 *
939 * @throws SecurityException
940 * If a security manager exists and its {@link
941 * java.lang.SecurityManager#checkRead(java.lang.String)}
942 * method denies read access to the file
943 */
944 public long lastModified() {
945 SecurityManager security = System.getSecurityManager();
946 if (security != null) {
947 security.checkRead(path);
948 }
949 if (isInvalid()) {
950 return 0L;
951 }
952 return fs.getLastModifiedTime(this);
953 }
954
955 /**
956 * Returns the length of the file denoted by this abstract pathname.
957 * The return value is unspecified if this pathname denotes a directory.
958 *
959 * <p> Where it is required to distinguish an I/O exception from the case
960 * that {@code 0L} is returned, or where several attributes of the same file
961 * are required at the same time, then the {@link
962 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
963 * Files.readAttributes} method may be used.
964 *
965 * @return The length, in bytes, of the file denoted by this abstract
966 * pathname, or <code>0L</code> if the file does not exist. Some
967 * operating systems may return <code>0L</code> for pathnames
968 * denoting system-dependent entities such as devices or pipes.
969 *
970 * @throws SecurityException
971 * If a security manager exists and its {@link
972 * java.lang.SecurityManager#checkRead(java.lang.String)}
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917 * last modified.
918 *
919 * <p> Where it is required to distinguish an I/O exception from the case
920 * where {@code 0L} is returned, or where several attributes of the
921 * same file are required at the same time, or where the time of last
922 * access or the creation time are required, then the {@link
923 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
924 * Files.readAttributes} method may be used.
925 *
926 * @apiNote
927 * While the unit of time of the return value is milliseconds,
928 * the granularity of the value depends on the underlying
929 * file system and may be larger. For example, some
930 * file systems use time stamps in units of seconds.
931 *
932 * @return A <code>long</code> value representing the time the file was
933 * last modified, measured in milliseconds since the epoch
934 * (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the
935 * file does not exist or if an I/O error occurs; the value may
936 * be negative in which case its absolute value indicates the
937 * number of milliseconds before the epoch; if the last-modified
938 * time is the epoch, the value will be unity (<code>1</code>)
939 * so as to avoid ambiguity with the case of a non-existent file
940 *
941 * @throws SecurityException
942 * If a security manager exists and its {@link
943 * java.lang.SecurityManager#checkRead(java.lang.String)}
944 * method denies read access to the file
945 */
946 public long lastModified() {
947 SecurityManager security = System.getSecurityManager();
948 if (security != null) {
949 security.checkRead(path);
950 }
951 if (isInvalid()) {
952 return 0L;
953 }
954 long lastModifiedTime = fs.getLastModifiedTime(this);
955
956 //
957 // In the infinitesimally probable event that the last-modified time
958 // of the file is the epoch (zero), return unity instead so as to avoid
959 // ambiguity with the case of a non-existent file which returns zero.
960 //
961 if (lastModifiedTime == 0) {
962 lastModifiedTime = 1;
963 }
964
965 return lastModifiedTime;
966 }
967
968 /**
969 * Returns the length of the file denoted by this abstract pathname.
970 * The return value is unspecified if this pathname denotes a directory.
971 *
972 * <p> Where it is required to distinguish an I/O exception from the case
973 * that {@code 0L} is returned, or where several attributes of the same file
974 * are required at the same time, then the {@link
975 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
976 * Files.readAttributes} method may be used.
977 *
978 * @return The length, in bytes, of the file denoted by this abstract
979 * pathname, or <code>0L</code> if the file does not exist. Some
980 * operating systems may return <code>0L</code> for pathnames
981 * denoting system-dependent entities such as devices or pipes.
982 *
983 * @throws SecurityException
984 * If a security manager exists and its {@link
985 * java.lang.SecurityManager#checkRead(java.lang.String)}
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