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Session 4: java.io package. Review. Bài tập 1: construct an application that calculates the number of days remaining in the current year. Click to edit Master text styles Second level Third level Fourth level Fifth level. 1. Files and Directories. Constructors: - File(String path) - PowerPoint PPT Presentation
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Session 4: java.io package
Review
Bài tập 1: construct an application that calculates the number of days remaining in the current year
Click to edit Master text stylesSecond level
Third level Fourth level
Fifth level
1. Files and Directories
Constructors:
- File(String path)
//1 para: is the path to a file or diretory
- File(String directoryPath, String filename)
//2 para: the path to a directory and the name of a file in that directory.
- File(File directory, String filename)
//2 para: a File object for a directory and the name of a file in that directory.
1. Files and Directories
boolean canRead //return true (file exists and can be read), false
boolean canWrite //return true (file exists and can be read), false
boolean delete //Deletes file. Return true (xóa thành công), false
boolean equals(Object obj) //return true (current object and obj refer to the same file)
boolean exists() //return true (the file exists)
1. Files and Directories
String getAbsolutePath() //return absolute path to the file
String getCanonicalPath() //return canonical path to the file
String getName() //return name of the file
String getParent() //return parent of the file
String getPath() //return path to the file
boolean isAbsolute() //return true (file path name is absolute)
boolean isDirectory() //return true (file is a directory)
1. Files and Directories
Boolean renameTo(File newName) // rename the file or directory to newName. Return true if (thay đổi thành công)
renameTo()
BT1: Write an application to rename a file. Use the renameTo() method of File to accomplish this task. The first command line argument is the old filename, the second is new filename
2. Character StreamsTo read and write characters and strings.
ReaderBufferedReader
InputStreamReader FileReader
InputStreamReader class extends Reader. It converts a stream of bytes to a stream of characters.
FileReader class extends InputStreamReader and inputs chracters from a file.
2. Character Streams
OutputStreamWritter class extends Writer. It converts a stream of characters to a stream of bytes.
FileWritter class extends OutputStreamWritter and outputs characters to a file.
Writer
BufferedWritter
OutputStreamWritter
PrintWritter
FileWritter
2. Character Streams
Ví dụ minh họa ghi và đọc file bằng cách sử dụng character streams
2. Character Streams
Click to edit Master text stylesSecond level
Third level Fourth level
Fifth level
• Ghi file
2. Character Streams
Đọc file
2. Character Streams
Bài tập về nhà 1:
Write an application that copies one character file to a second character file. The source file is the first command line argument and the destination file is the second command line argument.
3. Buffered Character Streams
BufferedWritter class extends Writer and buffers output to a character stream.
3. Buffered Character Streams
Ví dụ minh họa ghi và đọc file bằng cách sử dụng buffered character streams
3. Buffered Character Streams
Ghi file
3. Buffered Character Streams
Đọc file
4. Byte Stream
FileInputStream class extends InputStream and allows to read binary data from a file.
FilterInputStream class extends Inputstream and filters an input stream.
BufferedInputStream class extends FilterInputstream and buffers input from a byte stream.
DataInputStream class extends FilterInputStream and implements DataInput.
InputStreamFileInputStream
FilterInputStreamBufferedInputStream
DataInputStream
4. Byte Stream
FileOutputStream class extends OutputStream and allows to write binary data to a file.
FilterOutputStream class extends OutputStream , it is used to filter output.
BufferedOutputStream class extends FilterOutputStream and buffers output to a byte stream.
DataOutputStream class extends FilterOutputStream and inplements DataOutput.
OutputStreamFileOutputStream
FilterOutputStreamBufferedOutputStream
DataOutputStream
PrintStream
4. Byte Stream
Ví dụ minh họa 1: Sử dụng FileOutputStream và FileInputStream để ghi và đọc file
FileOutputStream và FileInputStream
Ghi file:
FileOutputStream và FileInputStream
Đọc file:
4. Byte Stream
Ví dụ minh họa 2: sử dụng BufferedOutputStream và BufferedInputStream để đọc và ghi file
BufferedOutputStream và BufferedInputStream
Ghi file
BufferedOutputStream và BufferedInputStream
Đọc file (BTVN 2)
4. Byte Stream
Ví dụ minh họa 3: sử dụng DataInputStream và DataOutputStream để ghi và đọc file
DataInputStream và DataOutputStream
Ghi file
DataInputStream và DataOutputStream
Đọc file (BTVN 3)
DataInputStream và DataOutputStream
BTVN 4: Write one application that writes the first 15 numbers of the Fibonacci series to a file. Use the writeShort() method of DataInputStream to output the numbers. Write a second application that reads this data from a file and display it. Use the readShort() method of DataOutputStream to input the number.
