This post shows various options to write to a file in Java.
In Java there are two classes FileWriter and FileOutputStream for writing to a file. Out of these two FileWriter is meant for writing streams of characters and FileOutputStream is used for writing streams of raw bytes.
In general, a Writer sends its output immediately to the underlying character or byte stream. Unless prompt output is required, it is advisable to wrap a BufferedWriter around any Writer whose write() operations may be costly, such as FileWriters and OutputStreamWriters.
So the classes you should use for writing to a file in Java are BufferedWriter and BufferedOutputStream.
To see different options available for reading a file in Java, check this post How to Read File in Java
Apart from these classes Files class added in Java 7 also provides methods for writing to a file in Java. There is Files.write() method to write bytes to a file. There is also a Files.newBufferedWriter() method which returns a BufferedWriter that may be used to write text to the file in an efficient manner.
So there are four options for writing to a file in Java-
- Using BufferedWriter
- Using BufferedOutputStream
- Using Files.write() method
- Using Files.newBufferedWriter() method
Java program to write to a file using BufferedWriter
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
public class WriteToFile {
public static void main(String[] args) {
writeFile("D:\\test.txt");
}
private static void writeFile(String fileName){
BufferedWriter bw = null;
try {
// wrapping FileWriter instance
bw = new BufferedWriter(new FileWriter(fileName));
bw.write("This is a test line");
bw.newLine();
bw.write("Line written by Java program in knpCode.com");
}catch (IOException exp){
exp.printStackTrace();
}finally{
if(bw != null){
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
Java program to write to a file using BufferedOutputStream
If you have to write raw bytes then you can use BufferedOutputStream class. In the example code getBytes() method is used to encode string into bytes.
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class WriteToFile {
public static void main(String[] args) {
writeFile("D:\\test.txt");
}
private static void writeFile(String fileName){
BufferedOutputStream bw = null;
try {
bw = new BufferedOutputStream(new FileOutputStream(fileName));
// may have to use \r\n for Windows OS
bw.write("This is a test line\n".getBytes());
bw.write("Line written by Java program in knpCode.com".getBytes());
}catch (IOException exp){
exp.printStackTrace();
}finally{
if(bw != null){
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
Java program to write to a file using Files.write() method
This method Writes bytes to a file so the content has to be passed as byte array.
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
public class WriteToFile {
public static void main(String[] args) {
String content = "This is a test line.\nLine written by Java program in knpCode.com.";
try {
Files.write(Paths.get("D:\\test.txt"), content.getBytes());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Java program to write to a file using Files.newBufferedWriter() method
public class WriteToFile {
public static void main(String[] args) {
BufferedWriter bw = null;
String content = "This is a test line.\nLine written by Java program in knpCode.com.";
try {
bw = Files.newBufferedWriter(Paths.get("D:\\test.txt"));
bw.write(content);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(bw != null){
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
Java 7 onward you can also use try-with-resources to close the resources automatically rather than closing them explicitly using finally block.
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
public class WriteToFile {
public static void main(String[] args) {
String content = "This is a test line.\nLine written by Java program in knpCode.com.";
try (BufferedWriter bw = Files.newBufferedWriter(Paths.get("D:\\test.txt"))) {
bw.write(content);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Related Posts
- How to Append to a File in Java
- Write a File Asynchronously in Java
- Write to Excel File in Java Using Apache POI
- How to Read Delimited File in Java
- How to Read File in Java
- Generate PDF From XML in Java Using Apache FOP
- Matrix Addition Java Program
- How to Convert String to float in Java
That’s all for the topic How to Write to a File in Java. If something is missing or you have something to share about the topic please write a comment.
You may also like
