Chapter 16 Simple Input and Output Prerequisites for part Iv Chapter 8 Inheritance and Polymorphism Chapter 15 Exceptions and assertions Chapter 16 Simple Input and Output 与人玫瑰,手有余香 Introduction to Java Programming, revised by Dai-kaiyu
Liang,Introduction to Java Programming,revised by Dai-kaiyu 1 Chapter 16 Simple Input and Output Prerequisites for Part IV Chapter 8 Inheritance and Polymorphism Chapter 16 Simple Input and Output Chapter 15 Exceptions and Assertions 与人玫瑰，手有余香
Objectives discover file properties, delete and rename files using the File class 16.2 To understand how I/O is processed in Java(S 16.3) To distinguish between text I/O and binary I/O(8 16.3) To read and write characters using FileReader and FileWriter(8 16.4) To improve the performance of text IO using Buffered Reader and Buffered Writer(816.4) To write primitive values, strings, and objects as text using Print Writer and Printstream(§164) To read and write bytes using FileInputStream and File OutputStream(8 16.6) To read and write primitive values and strings using DataInput Stream/Data QutputStream(8 16.6) To store and restore objects using ObjectOutputStream and ObjectInputStream, and to understand how objects are serialized and what kind of objects can be serialized(s 16.9 Optional) To use the Serializable interface to enable objects to be serializable($ 16.9 Optional) To use RandomAccessFile for both read andweriteal. yu1610 Optional)
Liang,Introduction to Java Programming,revised by Dai-kaiyu 2 Objectives To discover file properties, delete and rename files using the File class (§16.2). To understand how I/O is processed in Java (§16.3). To distinguish between text I/O and binary I/O (§16.3). To read and write characters using FileReader and FileWriter (§16.4). To improve the performance of text I/O using BufferedReader and BufferedWriter (§16.4). To write primitive values, strings, and objects as text using PrintWriter and PrintStream(§16.4). To read and write bytes using FileInputStreamand FileOutputStream (§16.6). To read and write primitive values and strings using DataInputStream/DataOutputStream(§16.6). To store and restore objects using ObjectOutputStreamand ObjectInputStream, and to understand how objects are serialized and what kind of objects can be serialized (§16.9 Optional). To use the Serializable interface to enable objects to be serializable (§16.9 Optional). To use RandomAccessFile for both read and write. (§16.10 Optional)
Introduction ● files OLong-term storage of large amounts of data PErsistent data exists after termination of program O Files stored on secondary storage devices Magnetic disks ● Optical disks Magnetic tapes O Sequential and random access files Introduction to Java Programming, revised by Dai-kaiyu
Liang,Introduction to Java Programming,revised by Dai-kaiyu 3 Introduction ⚫Files Long-term storage of large amounts of data Persistent data exists after termination of program Files stored on secondary storage devices ⚫Magnetic disks ⚫Optical disks ⚫Magnetic tapes Sequential and random access files
The File class The File class is intended to provide an abstraction that deals with most of the machine-dependent complexities of files and path names in a machine-independent fashion The filename is a string .The File class is a wrapper class for the file name and its directory path Introduction to Java Programming, revised by Dai-kaiyu
Liang,Introduction to Java Programming,revised by Dai-kaiyu 4 The File Class ⚫The File class is intended to provide an abstraction that deals with most of the machine-dependent complexities of files and path names in a machine-independent fashion. The filename is a string. ⚫The File class is a wrapper class for the file name and its directory path
java.io. File Obtaining file +File(pathname: String) Creates a File object for the specified pathname. The pathname may be a ctory or a file properties an +File(parent: String, child: String) Creates a File object for the child under the directory parent. child may be a manipulating file filename or a subdirectory. +File(parent: File, child: String)Creates a File object for the child under the directory parent. parent is a File object. In the preceding constructor, the parent is a string +exists: boolean Returns true if the file or the directory represented by the file object exists +canReado: boolean Returns true if the file represented by the file object exists and can be read +can Write(: boolean Returns true if the file represented by the File object exists and can be written +isDirectoryO: boolean Returns true if the File object represents a directory +isFile(: boolean Returns true if the File object represents a file isAbsoluteO): boolean Returns true if the File object is created using an ab atn name +isHiddeno: boolean Returns true if the file represented in the File object is hidden. The exact definition of hidden is system-dependent. On Windows, you can mark a file hidden in the File Properties dialog box. On Unix systems, a file is hidden if its name begins with a period character getAbsolutePathO: String Returns the complete absolute file or directory name represented by the File +getCanonicalPathO: String Returns the same as get AbsolutePatho except that it removes redundant names, such as"."and".", from the pathname, resolves symbolic links(on Unix platforms), and converts drive letters to standard uppercase(on Win32 +getName( String Returns the last name of the complete directory and file name represented by the File object. For example, new File("c: booklltest dat").getNameO returns +getPatho: String Returns the complete directory and file name represented by the File object For example, new File("c: \lbookltest dat").get Patho returns c: \bookltest dat etParento: string Returns the complete parent directory of the current directory or the file represented by the File object. For example, new File("c: lbooklltest dat")-getParento returns c: \book +lastModifiedo long Returns the time that the file was last modified delete(: boolean Deletes this file. The method returns true if the deletion succeeds +renameTo(dest: File): boolean Renames this file. The method returns true if the operation succeeds
Liang,Introduction to Java Programming,revised by Dai-kaiyu 5 java.io.File +File(pathname: String) +File(parent: String, child: String) +File(parent: File, child: String) +exists(): boolean +canRead(): boolean +canWrite(): boolean +isDirectory(): boolean +isFile(): boolean +isAbsolute(): boolean +isHidden(): boolean +getAbsolutePath(): String +getCanonicalPath(): String +getName(): String +getPath(): String +getParent(): String +lastModified(): long +delete(): boolean +renameTo(dest: File): boolean Creates a File object for the specified pathname. The pathname may be a directory or a file. Creates a File object for the child under the directory parent. child may be a filename or a subdirectory. Creates a File object for the child under the directory parent. parent is a File object. In the preceding constructor, the parent is a string. Returns true if the file or the directory represented by the File object exists. Returns true if the file represented by the File object exists and can be read. Returns true if the file represented by the File object exists and can be written. Returns true if the File object represents a directory. Returns true if the File object represents a file. Returns true if the File object is created using an absolute path name. Returns true if the file represented in the File object is hidden. The exact definition of hidden is system-dependent. On Windows, you can mark a file hidden in the File Properties dialog box. On Unix systems, a file is hidden if its name begins with a period character '.'. Returns the complete absolute file or directory name represented by the File object. Returns the same as getAbsolutePath() except that it removes redundant names, such as "." and "..", from the pathname, resolves symbolic links (on Unix platforms), and converts drive letters to standard uppercase (on Win32 platforms). Returns the last name of the complete directory and file name represented by the File object. For example, new File("c:\\book\\test.dat").getName() returns test.dat. Returns the complete directory and file name represented by the File object. For example, new File("c:\\book\\test.dat").getPath() returns c:\book\test.dat. Returns the complete parent directory of the current directory or the file represented by the File object. For example, new File("c:\\book\\test.dat").getParent() returns c:\book. Returns the time that the file was last modified. Deletes this file. The method returns true if the deletion succeeds. Renames this file. The method returns true if the operation succeeds. Obtaining file properties and manipulating file