Java 缓冲写入器-java教程-PHP中文网

The java BufferedWriter is a class that is used to provide buffering for writing text to the character output stream. The BufferedWriter makes the fast performance and efficient writing of the character, string, and single array. The BufferedWriter class is a built-in class in java that is defined in the java.io.BufferedWriter package.

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The java.io.Writer class is a superclass of the BufferedWriter. The buffer size may or may not be specified; when the size of the buffer is not specified, then its size will be the default size that is large enough for most of the purpose. In comparison to Filewriter, the BufferedWriter writes the large chunks of data, so it is used to make FileWriter (lower level class) more efficient and easy to use.

Syntax

Following is the declaration for the java.io.BufferedWriter class.

public class BufferedWriter extends Writer
{
// Constructors and methods of the BufferedWriter class
}

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The above is the syntax of the BufferedWriter, where it is extended to the Writer class.

BufferedWriter class member Functions: The BufferedWriter class contains constructors and some functions as a BufferedWriter class member function.

Constructors

BufferedWriter( Writer out): This constructor creates an instance of BufferedWriter, which uses a default size of an output buffer.
BufferedWriter( Writer out, int size): This constructor creates an instance of BufferedWriter, which uses an output buffer of the specified size.

Functions of BufferedWriter Class

Below are the functions mentioned :

1. write(int character): This function is used to write a single character.

Syntax:

public void writes (int character).

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2. write(char[] cbuf, int off, intlen): This function is used to write an array cbufof characters len bytes at offset off to the file.

Syntax:

public void write(char[] cbuf, int off, intlen)

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3. write(String s, int off, intlen): This function is uses to write a string of len length at offset off to the file.

Syntax:

public void write(String s, int off, intlen)

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4. flush(): This function is uses to flushes the input stream.

Syntax:

public void flush()

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5. newLine(): This function is used to write a line separator defined by the system property line.separator.

Syntax:

public void newLine()

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6. close(): This function is used to closes the file and release the input stream resource.

Syntax:

public void close()

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Examples to Implement Java BufferedWriter

Working and examples are mentioned below:

Example #1

Next, we write the java code to understand the BufferedWriter class more clearly. The following example is where we create a BufferedWriter object by using the BufferedWriter class constructor and passing the file name to write a character, as below.

Code:

//package p1;
import java.io.BufferedWriter;
import java.io.FileWriter;
public class Demo
{
public static void main( String[] arg) {
// create object of file input stream by opening connection data.txt file
try {
FileWriter fobj=new FileWriter("D:\\data.txt");
// create object of the BufferedWriter
BufferedWriter bobj = new BufferedWriter(fobj);
System.out.println("Buffered start writing : ");
// Use write() function
bobj.write('H');
bobj.write('E');
// writing l
bobj.write(108);
bobj.write(108);
// writing o!
bobj.write('o');
bobj.write('!');
// Closing BufferWriter to end operation
bobj.close();
System.out.println("Buffered writing done. you can open the file.");
}catch(Exception e)
{
System.out.println(e);
}
}
}

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An output of the above code is

Java 缓冲写入器

Note: While we are performing any write operations to the file, we should not keep open that file; if we do, then the file cannot be updated or written.

Now, if we open the thedata.txt file, we can see that the content is written, as we can see below.

Java 缓冲写入器

Example #2

Next, we write the java code to understand the BufferedWriter class more clearly, where we create aBufferedWriter object to write the string to the file with the associated buffer, as below.

Code:

//package p1;
import java.io.BufferedWriter;
import java.io.FileWriter;
public class Demo
{
public static void main( String[] arg) {
// create object of file input stream by opening connection data.txt file
try {
FileWriter fobj=new FileWriter("D:\\data.txt");
// create object of the BufferedWriter
BufferedWriter bobj = new BufferedWriter(fobj);
System.out.println("Buffered start writing : ");
int offs = 4;
String str = "This is an example for Buffered writer";
bobj.write(str,offs,str.length()-offs);
//CloseBufferWriter to end operation
bobj.close();
System.out.println("Buffered writing done. you can open the file.");
}catch(Exception e)
{
System.out.println(e);
}
}
}

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An output of the above code is:

Java 缓冲写入器

When we open the data.txt file, we can see that the content is written, as we can see below:

Java 缓冲写入器

Example #3

Next, we write the java code to understand the BufferedWriter class more clearly where we create a BufferedWriter object to write the string to the file and to move the next line while writing; we will use the newLine() function, as below.

Code:

//package p1;
import java.io.BufferedWriter;
import java.io.FileWriter;
public class Demo
{
public static void main( String[] arg) {
// create object of file input stream by opening connection data.txt file
try {
FileWriter fobj=new FileWriter("D:\\data.txt");
// create object of the BufferedWriter
BufferedWriter bobj = new BufferedWriter(fobj);
System.out.println("Buffered start writing : ");
bobj.write("This is an ");
// Next line
bobj.newLine();
bobj.write("Example for");
// Next line
bobj.newLine();
// Printing "GEEKS"
bobj.write("BufferedWriter");
// close BufferWriter to end operation
bobj.close();
System.out.println("Buffered writing done. you can open the file.");
}catch(Exception e)
{
System.out.println(e);
}
}
}

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An output of the above code is:

Java 缓冲写入器