Category : Java | Sub Category : Java Programs | By Prasad Bonam Last updated: 2020-10-02 14:55:29 Viewed : 559
Provides for system input and output through data
streams, serialization and the file system. Unless otherwise noted, passing a
null argument to a constructor or method in any class or interface in this
package will cause a NullPointerException to be thrown.
This class consists exclusively of static methods that operate on files,
directories, or other types of files.
In most cases, the methods defined here will delegate to the associated file
system provider to perform the file operations.
Since:
1.7
Path java.nio.file.Files.write(Path path, byte[]
bytes, OpenOption...
options) throws IOException
ReadAndWrite.java
package
runnerdev.io.file;
import
java.io.IOException;
import
java.nio.file.Files;
import
java.nio.file.Path;
import
java.nio.file.Paths;
import
java.nio.file.StandardOpenOption;
import
java.util.List;
public class ReadAndWrite {
public static void main(String[] args) throws
IOException {
String filePath = "C:/Downloads/runnerdev/java/";
String input = readTextFile(filePath + "readTestFile.txt");
writeToTextFile(filePath + "writeCopy.txt", input);
readTextFile(filePath + "writeCopy.txt");
readTextFileByLines(filePath + "readTestFile.txt");
Path path =
Paths.get(filePath + "readTestFile.txt");
path.getFileName().compareTo(path.getFileName());
}
public static String readTextFile(String fileName) throws
IOException {
String readTextFile = new
String(Files.readAllBytes(Paths.get(fileName)));
System.out.println("readTextFileByLines:
" + readTextFile);
return readTextFile;
}
public static List<String> readTextFileByLines(String fileName) throws
IOException {
List<String> readLines =
Files.readAllLines(Paths.get(fileName));
System.out.println("readTextFileByLines:
" + readLines);
return readLines;
}
public static void writeToTextFile(String fileName,
String writeData) throws IOException {
Files.write(Paths.get(fileName), writeData.getBytes(),
StandardOpenOption.CREATE);
System.out.println("writeToTextFile
is done");
}
}
OutPut:
Creates a buffering character-input stream that uses a default-sized input
buffer
Prior to Java SE 7, you can use a finally
block
to ensure that a resource is closed regardless of whether the try
statement
completes normally or abruptly. The following example uses a finally
block
instead of a try
-with-resources
statement:
static String readFirstLineFromFileWithFinallyBlock(String path)
throws IOException {
BufferedReader br = new BufferedReader(new FileReader(path));
try {
return br.readLine();
} finally {
if (br != null) br.close();
}
}
JDK 1.7 try-with-resources
to auto close the resources
static
String readFirstLineFromFile(String path) throws IOException {
try
(BufferedReader br =
new BufferedReader(new
FileReader(path))) {
return br.readLine();
}
ReadFileWithTryResource.java
package
runnerdev.io.file;
import
java.io.BufferedReader;
import
java.io.FileReader;
import java.io.IOException;
public class
ReadFileWithTryResource {
public static void main(String[] args) {
String filePath = "C:Downloads
unnerdevjava";
try
(FileReader reader = new FileReader(filePath+"readTestFile.txt");
BufferedReader br = new
BufferedReader(reader)) {
String line;
while ((line = br.readLine())
!= null) {
System.out.println(line);
}
} catch (IOException e) {
System.err.format("IOException:
%s%n", e);
}
}
}
Output:
thank you for
downloading project from runnerdev.com
ReadAndWrite example
Return
a Stream that is lazily populated with Path by walking the file tree rooted at
a given starting file. The file tree is traversed depth-first, the
elements in the stream are Path
objects that are obtained as if by resolving
the relative path against start.
This
method works as if invoking it were equivalent to evaluating the expression:
walk(start, Integer.MAX_VALUE, options)
package
runnerdev.io.file;
import
java.io.IOException;
import
java.nio.file.Files;
import
java.nio.file.Paths;
public class
ReadFilesFromDir {
public static void main(String[] args) {
String filePath = "C:/Downloads/runnerdev/java/";
try {
Files.walk(Paths.get(filePath)).filter(Files::isRegularFile).forEach(System.out::println);
} catch
(IOException e) {
e.printStackTrace();
}
}
package
runnerdev.io.file;
import
java.io.File;
import
java.io.IOException;
import
java.nio.file.Files;
import
java.nio.file.Path;
import
java.util.Comparator;
public class
DeleteFile {
public static void main(String[] args) {
String filePath = "C:/Downloads/runnerdev/java/";
try {
Path path = new File(filePath).toPath(); Files.walk(path).sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(File::delete);
}
catch (IOException e) {
e.printStackTrace();
}
}
}
FileExist.java
package runnerdev.io.file;
import java.io.File;
public class FileExist {
public static void main(String[] args) {
String filePath = "C:/Downloads/runnerdev/java/testFile.txt";
File f = new File(filePath);
if (f.exists()
&& !f.isDirectory())
{
System.out.println("File is existed!!");
} else {
System.out.println("File is not existed!!");
}
}
package
runnerdev.io.file;
import
java.io.File;
public class
CompareFile {
public static void main(String[] args) {
String filePath = "C:/Downloads/runnerdev/java/";
File file1 = new File(filePath + "readTestFile.txt");
File file2 = new File(filePath + "readTestFile.txt"");
if (file1.compareTo(file2) ==
0) {
System.out.println("Both
the paths are equal");
} else {
System.out.println("Both
the paths are not equal");
}
}
}
Both the paths are equal
7. Remove white Space from
fileNames and comapre fileNames
RemoveWhiteSpace.java
import
java.io.File;
import
java.nio.file.Path;
import
java.nio.file.Paths;
public class RemoveWhiteSpace {
public static void main(String[] args) {
String fileName1 = "ReadTestFile.txt";//
get fileName from database
String folderFilePath = "C:/Users/Downloads/runnerdev/test/";
removeWhiteSpace(folderFilePath);
Path path =
Paths.get(folderFilePath + "readTestFile.txt");//
localFileName
String fileName = path.getFileName().toString();
fileName1 = fileName1.toString();
System.out.println("fileName:" + fileName);
System.out.println("fileName1:" + fileName1);
/*** Below logic is used to
compare the file Names. */
if (fileName.equalsIgnoreCase(fileName1)) {
System.out.println("FileNames
are matched");
} else {
System.out.println("FileNames
are not matched");
}
}
/*** Below logic is used to remove the white space from the file
Names. */
static void removeWhiteSpace(String folderFilePath) {
File folderFiles = new File(folderFilePath);
System.out.println("folderFiles=>" + folderFiles + "
folderFiles.listFiles()=>" + folderFiles.listFiles());
try {
if (folderFiles.listFiles()
!= null) {
for (File
old : folderFiles.listFiles()) {
String oldName = old.getName();
System.out.println("OldFileName
is: " + oldName);
if (!oldName.contains("
"))
continue;
String newName = oldName.replaceAll("s", "");
old.renameTo(new File(folderFiles + "/" + newName));
System.out.println("renameTo
NewFileName: " + newName);
}
}
} catch
(Exception e) {
e.printStackTrace();
}
}
}
7. Remove white Space from
fileNames
RemoveWhiteSpace.java
import
java.io.File;
import
java.nio.file.Path;
import
java.nio.file.Paths;
public class RemoveWhiteSpace {
public static void main(String[] args) {
String folderFilePath = "C:/Users/Downloads/runnerdev/test/";
removeWhiteSpace(folderFilePath);
}
/*** Below logic is used to remove the white space from the file
Names. */
static void removeWhiteSpace(String folderFilePath) {
File folderFiles = new File(folderFilePath);
System.out.println("folderFiles=>" + folderFiles + "
folderFiles.listFiles()=>" + folderFiles.listFiles());
try {
if (folderFiles.listFiles()
!= null) {
for (File
old : folderFiles.listFiles()) {
String oldName = old.getName();///read T est File.txt
System.out.println("OldFileName
is: " + oldName);
if (!oldName.contains("
"))
continue;
String newName = oldName.replaceAll("s", "");//
old.renameTo(new File(folderFiles + "/" + newName));
System.out.println("renameTo
NewFileName: " + newName);
}
}
} catch
(Exception e) {
e.printStackTrace();
}
}
}
OutPut
:
folderFiles=>C:UsersDownloads
unnerdev est
folderFiles.listFiles()=>[Ljava.io.File;@15db9742
OldFileName
is: read T est File.txt
renameTo
NewFileName: readTestFile.txt
8. Compare two fileNames:
public class comapreFileNames {
public static void main(String[] args) {
/***
Below logic is used to compare the file Names. */
String fileName1 = "ReadTestFile.txt";//
get fileName from database
Path path =
Paths.get(folderFilePath + "readTestFile.txt");//
localFileName
String fileName = path.getFileName().toString();
fileName1 = fileName1.toString();
System.out.println("fileName:" + fileName);
System.out.println("fileName1:" + fileName1);
if (fileName.equalsIgnoreCase(fileName1)) {
System.out.println("FileNames
are matched");
} else {
System.out.println("FileNames
are not matched");
}
}
}
Output:
fileName:readTestFile.txt
fileName1:ReadTestFile.txt
FileNames are matched