Java language input and output stream operation skills

Java language input and output stream operation skills

The Java language provides developers with many convenient input and output stream classes, making file reading and writing operations very simple and efficient. In this article, we will introduce the basic knowledge of Java language input and output streams and some common operation techniques.

Java input and output streams: Overview

Java input and output streams are a mechanism that uses some predefined classes to read and write data streams or data blocks. They are classes under the Java.io package that can read and write various data types, such as text, binary, pictures, etc. Java input stream is used to read the input stream and Java output stream is used to write the output stream. In addition, Java input and output streams can also be used to read and write network sockets, files, and other input and output devices.

Classification of Java input and output streams

Java input and output streams can be divided into four main types:

1. Byte Stream: Use binary form to Read and write data. It is a subclass of the abstract classes InputStream and OutputStream. BufferedInputStream and BufferedOutputStream can improve reading and writing efficiency.
2. Character Stream: Use character form to read and write data. It is a subclass of the abstract classes Reader and Writer. BufferedReader and BufferedWriter can improve reading and writing efficiency.
3. Object Stream: used to read and write Java objects. It is a subclass of ObjectInputStream and ObjectOutputStream.
4. Compression Stream: used to read and write compressed and decompressed data. It is a subclass of GZIPInputStream, GZIPOutputStream, InflaterInputStream and DeflaterOutputStream.

Java input and output stream operation skills

The following introduces some commonly used Java input and output stream operation skills:

1. Using the BufferedInputStream and BufferedOutputStream classes can improve reading Writing efficiency. They can cache data in memory and only write it to disk when the cache is full or certain conditions are met.
2. For large files, use the RandomAccessFile class to quickly read and write data at any location.
3. For text files, you can use the FileReader or FileWriter class to read and write. When reading and writing, you need to specify the character encoding. You can use the code:

FileReader fr = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fr);
String line;
while ((line = br.readLine()) != null) {
    System.out.println(line);
}
br.close();
fr.close();

4. For binary files, you can use the DataInputStream and DataOutputStream classes to read and write. Note that you need to specify the data type and byte size to write when writing. You can use the code:

DataOutputStream out = new DataOutputStream(
    new BufferedOutputStream(
        new FileOutputStream("binary.dat")));
out.writeInt(123);
out.writeDouble(3.14159);
out.writeChar('A');
out.close();

DataInputStream in = new DataInputStream(
    new BufferedInputStream(
        new FileInputStream("binary.dat")));
System.out.println(in.readInt());
System.out.println(in.readDouble());
System.out.println(in.readChar());
in.close();

5. When reading a binary file in a loop, you can use the EOFException exception to determine whether the file has been Read completed. If an exception is read, it means that the reading has been completed.

DataInputStream in = new DataInputStream(
    new BufferedInputStream(
        new FileInputStream("binary.dat")));
try {
    while (true) {
        int i = in.readInt();
        double d = in.readDouble();
        char c = in.readChar();
        System.out.println(i + " " + d + " " + c);
    }
} catch (EOFException e) {
    System.out.println("文件读取完毕");
}
in.close();

Conclusion

Java input and output streams are a very important part of Java programming. This article introduces the basic knowledge and common operation techniques of Java input and output streams. Through in-depth study and use of Java input and output streams, the reading and writing efficiency and performance of Java programs can be greatly improved.

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