1) Create File on location given by you on any operating system.
package com.myapp.filehandling;
import java.io.File;
import java.io.IOException;
public class CreateFile {
public static void main(String[] args) {
// give the path where you want to create file
File file = new File("d:\\newfile.txt");
try {
// file.createNewFile() create new file on location given by you and
// return true if created successfully else throws exception
// IOException
if (file.createNewFile()) {
System.out.println("File is created!");
} else {
System.out.println("File already exists.");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
package com.myapp.filehandling;
import java.io.File;
import java.io.IOException;
public class CreateFile {
public static void main(String[] args) {
// give the path where you want to create file
File file = new File("d:\\newfile.txt");
try {
// file.createNewFile() create new file on location given by you and
// return true if created successfully else throws exception
// IOException
if (file.createNewFile()) {
System.out.println("File is created!");
} else {
System.out.println("File already exists.");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
2)Reading and Writing Byte by Byte.
package com.myapp.filehandling;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class ReaderWriterClassExample {
public static void main(String[] args) throws IOException {
FileReader inputStream = null;
FileWriter outputStream = null;
try {
inputStream = new FileReader("d:\\oldfile.txt");
outputStream = new FileWriter("e:\\newfile.txt");
int c;
long starttime = System.currentTimeMillis();
while ((c = inputStream.read()) != -1) {
outputStream.write(c);
}
long endtime = System.currentTimeMillis();
// This take too much time because of byte by byte reading and then
// writing each time accessing file for reading and then write to
// file is expensive so use BufferReader PrintWriter for fast
// reading and writing
System.out.println(endtime - starttime);
} finally {
if (inputStream != null) {
inputStream.close();
}
if (outputStream != null) {
outputStream.close();
}
}
}
}
3) Fast reading from and writing to file.
package com.myapp.filehandling;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
public class BufferReaderPrintWriterExample {
public static void main(String[] args) throws IOException {
BufferedReader inputStream = null;
PrintWriter outputStream = null;
try {
inputStream = new BufferedReader(new FileReader("d:\\oldfile.txt"));
outputStream = new PrintWriter(new FileWriter("e:\\newfile.txt"));
String l;
long starttime = System.currentTimeMillis();
while ((l = inputStream.readLine()) != null) {
outputStream.println(l);
}
long endtime = System.currentTimeMillis();
// this take hardly one milisec to execute file reading and writing
// so use this classes always
System.out.println(endtime - starttime);
} finally {
if (inputStream != null) {
inputStream.close();
}
if (outputStream != null) {
outputStream.close();
}
}
}
}
4) Create File depends on operating system.
package com.myapp.filehandling;
import java.io.File;
import java.io.IOException;
public class CreateFileAsOperatingSystem {
public static void main(String[] args) {
try {
String filename = "testing.txt";
String finalfile = "";
// below line of code give you directory where your program executes
String workingDir = System.getProperty("user.dir");
// below system property give you operating system name
String your_os = System.getProperty("os.name").toLowerCase();
if (your_os.indexOf("win") >= 0) {// windows
finalfile = workingDir + "\\" + filename;
} else if (your_os.indexOf("nix") >= 0// unix
|| your_os.indexOf("nux") >= 0) {// linux
finalfile = workingDir + "/" + filename;
} else {
finalfile = workingDir + "{others}" + filename;
}
System.out.println("Final filepath : " + finalfile);
File file = new File(finalfile);
if (file.createNewFile()) {
System.out.println("Done");
} else {
System.out.println("File already exists!");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
5)Create File without knowing your operating system.
package com.myapp.filehandling;
import java.io.File;
import java.io.IOException;
public class CreateFileWithFileSepaerator {
public static void main(String[] args) {
try {
String filename = "testing1.txt";
String myFile = "";
String workingDir = System.getProperty("user.dir");
// File.Seperator give you slash according to your operating system
// you no need to get operating system and then define your own
// seperator with this property
myFile = workingDir + File.separator + filename;
System.out.println("Final filepath : " + myFile);
File file = new File(myFile);
if (file.createNewFile()) {
System.out.println("Done");
} else {
System.out.println("File already exists!");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
6) Know about you file details?
package com.myapp.filehandling;
import java.io.File;
import java.io.IOException;
public class FilePermissionExample {
public static void main( String[] args )
{
try {
String filename = "testing1.txt";
String finalfile = "";
String workingDir = System.getProperty("user.dir");
finalfile = workingDir + File.separator + filename;
System.out.println("Final filepath : " + finalfile);
File file = new File(finalfile);
if(file.exists()){
System.out.println("Is Execute allow : " + file.canExecute());
System.out.println("Is Write allow : " + file.canWrite());
System.out.println("Is Read allow : " + file.canRead());
}
file.setExecutable(false);
file.setReadable(false);
file.setWritable(false);
System.out.println("Is Execute allow : " + file.canExecute());
System.out.println("Is Write allow : " + file.canWrite());
System.out.println("Is Read allow : " + file.canRead());
if (file.createNewFile()){
System.out.println("File is created!");
}else{
System.out.println("File already exists.");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
