Sometimes you may want to create temporary file in Java to store some data for the application. Once the job is done temp file can safely be discarded or you can delete it on exit. In this post we'll see how to create a temporary file in Java and how to read and write to temporary file.
In java.io.File class there are two methods for creating a temp file.
- static File createTempFile(String prefix, String suffix, File directory)- Creates a new empty file in the specified directory, using the passed prefix and suffix strings to generate file name.
- static File createTempFile(String prefix, String suffix)- Creates an empty file in the default temporary-file directory, using the given prefix and suffix to generate its name.
In java.nio.file.Files class also there are two methods for creating temporary files.
- static Path createTempFile(Path dir, String prefix, String suffix, FileAttribute<?>... attrs)- Creates a new empty file in the specified directory, using the given prefix and suffix strings to generate its name. You can also pass an optional list of file attributes to set atomically when creating the file
- static Path createTempFile(String prefix, String suffix, FileAttribute<?>... attrs)- Creates an empty file in the default temporary-file directory, using the given prefix and suffix to generate its name.
Creating temporary file using java.io.File class methods
import java.io.File;
import java.io.IOException;
public class TempFile {
public static void main(String[] args) {
try {
// Using default directory
File tempFile = File.createTempFile("MyFile", ".temp");
System.out.println("Temp file path- " + tempFile.getCanonicalPath());
// Specifying directory
File testFile = File.createTempFile("MyFile", ".temp", new File("F:\\Temp"));
System.out.println("Temp file path- " + testFile.getCanonicalPath());
tempFile.deleteOnExit();
testFile.deleteOnExit();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Output
Temp file path- C:\Users\netjs\AppData\Local\Temp\MyFile13999667283141733746.temp Temp file path- F:\Temp\MyFile11668072031090823667.temp
Creating temporary file using java.nio.file.Files class methods
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
public class TempFile {
public static void main(String[] args) {
try {
// Using default directory
Path tempFile = Files.createTempFile("MyFile", ".temp");
System.out.println("Temp file path- " + tempFile);
// Specifying directory
Path testFile = Files.createTempFile(Path.of("F:\\Temp"), "MyFile", ".temp");
System.out.println("Temp file path- " + testFile);
// Read write temp file operations
// delete file on exit
tempFile.toFile().deleteOnExit();
testFile.toFile().deleteOnExit();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Output
Temp file path- C:\Users\Anshu\AppData\Local\Temp\MyFile2647482374773079441.temp Temp file path- F:\Temp\MyFile16822359990880283479.temp
Reading and writing temporary file in Java
Once the temporary file is created you will of course use it to write some data and read some data from the temp file. You can use BufferedWriter and BufferedReader for writing to and reading from a temp file.
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class TempFile {
public static void main(String[] args) {
try {
// Specifying directory
File testFile = File.createTempFile("MyFile", ".temp", new File("F:\\Temp"));
System.out.println("Temp file path- " + testFile.getCanonicalPath());
testFile.deleteOnExit();
// Writing to temp file
BufferedWriter bw = new BufferedWriter(new FileWriter(testFile));
bw.write("Writing to the temp file");
bw.close();
// Reading from temp file
String str;
BufferedReader br = new BufferedReader(new FileReader(testFile));
while((str = br.readLine()) != null){
System.out.println("Line is - " + str);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Output
Temp file path- F:\Temp\MyFile16468233438314323721.temp Line is - Writing to the temp file
That's all for this topic Creating Temporary File in Java. If you have any doubt or any suggestions to make please drop a comment. Thanks!
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