A comparison of the read and write operations of files in Java

Compare read-write operations in Java compared to files

Author: Jeru Liu
Date: November 29,2000
Version: 1.0

Java for the file to read and write operations of many examples, so that beginners feel very confused, I think it is necessary to carry out various methods
Analyze, classify, and clarify the similarities and differences between different methods.

A In JDK 1.0, it is common to read and write using the InputStream & OutputStream two base classes.
The FileInputStream in InputStream is similar to a file handle, which is used to manipulate the file, similar to the
We have fileoutputstream this object in OutputStream.

The common way to read data using FileInputStream is:
FileInputStream fstream = new FileInputStream (args[0]);
DataInputStream in = new DataInputStream (fstream);
Use In.readline () to get the data, and then close the input stream with In.close ().
See Example 1 for complete code.

The common way to write data using FileOutputStream is:
FileOutputStream out = new FileOutputStream ("MyFile.txt");
PrintStream p = new PrintStream (out);
Use P.PRINTLN () to write the data, and then close the input with P.close ().
See Example 2 for complete code.


Two In JDK 1.1, two new object Reader & Writer are supported, which can only be used to manipulate text files, and
InputStream & OutputStream in JDK1.1 can operate on either a text file or a binary file.

The common way to read files using FileReader is:
FileReader FR = new FileReader ("MyData.txt");
BufferedReader br = new BufferedReader (FR);
Use Br.readling () to read out the data, then close the cache with Br.close (), and close the file with Fr.close ().
See Example 3 for complete code.

The common way to write files using FileWriter is:
FileWriter FW = new FileWriter ("MyData.txt");
PrintWriter out = new PrintWriter (FW);
The only difference between Out.print and out.println is writing data in Out.print or out.println files.
Enter the data or it will automatically open a new line. After writing, remember to turn off the output with Out.close () and close the file with Fw.close ().
See Example 4 for complete code.

--------------------------------------------------------------Following is the source code of Examples------------------------------------------------------

Example 1:
Fileinputdemo
Demonstrates FileInputStream and DataInputStream
Import java.io.*;

Class Fileinputdemo {
public static void Main (String args[]) {
Args.length is equivalent to ARGC in C
if (args.length = = 1) {
try {
The Open the file is the ' the ' ' the '
FileInputStream fstream = new FileInputStream (args[0]);
Convert our input stream to a DataInputStream
DataInputStream in = new DataInputStream (fstream);
Continue to read lines while there are still some left to read
while (In.available ()!=0) {
Print File line to screen
System.out.println (In.readline ());
}
In.close ();
catch (Exception e) {
SYSTEM.ERR.PRINTLN ("File input Error");
}
}
Else
System.out.println ("Invalid parameters");
}
}

Example 2:
Fileoutputdemo
Demonstration of FileOutputStream and PrintStream classes
Import java.io.*;

Class Fileoutputdemo
{
public static void Main (String args[]) {
FileOutputStream out; Declare a file output object
PrintStream p; Declare a print Stream object

try {
Connected to "MyFile.txt"
out = new FileOutputStream ("MyFile.txt");
Connect print stream to the output stream
p = new PrintStream (out);
P.println ("This is written to a file");
P.close ();
catch (Exception e) {
System.err.println ("Error writing to File");
}
}
}

Example 3:
Filereadtest.java
User FileReader in JDK1.1 to read a file
Import java.io.*;

Class Filereadtest {
public static void Main (string[] args) {
Filereadtest t = new filereadtest ();
T.readmyfile ();
}

void Readmyfile () {
String record = null;
int reccount = 0;
try {
FileReader FR = new FileReader ("MyData.txt");
BufferedReader br = new BufferedReader (FR);
Record = new String ();
while (The record = Br.readline ())!= null) {
reccount++;
System.out.println (RecCount + ":" + record);
}
Br.close ();
Fr.close ();
catch (IOException e) {
System.out.println ("Uh Oh, got an IOException error!");
E.printstacktrace ();
}
}

}

Example 4:
Filewritetest.java
User FileWriter in JDK1.1 to writer a file
Import java.io.*;

Class Filewritetest {
public static void Main (string[] args) {
Filewritetest t = new filewritetest ();
T.writemyfile ();
}

void Writemyfile () {
try {
FileWriter FW = new FileWriter ("MyData.txt");
PrintWriter out = new PrintWriter (FW);
Out.print ("Hi,this'll be wirte into the file!");
Out.close ();
Fw.close ();
catch (IOException e) {
System.out.println ("Uh Oh, got an IOException error!");
E.printstacktrace ();
}
}

}