How to convert primitive data into wrapper class using Java?

Java provides certain classes called wrapper classes in the java.lang package. The objects of these classes wrap primitive datatypes within them.

Using wrapper classes, you can also add primitive datatypes to various Collection objects such as ArrayList, HashMap etc. You can also pass primitive values over network using wrapper classes.

Example

Live Demo

import java.util.Scanner;
public class WrapperExample {
   public static void main(String args[]){
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter an integer value: ");
      int i = sc.nextInt();      
      //Wrapper class of an integer
      Integer obj = new Integer(i);
      //Converting Integer object to String
      String str = obj.toString();      
      System.out.println(str);
      //Comparing with other object
      int result = obj.compareTo(new Integer("124"));
      if(result==0) {
         System.out.println("Both are equal");
      }else{
         System.out.println("Both are not equal");
      }
   }
}

Output

Enter an integer value:
1211
1211
Both are not equalHow to create and use directories in Java?

Creating directories

Just like the file class the Files class of java.nio package provides createTempFile() method which accepts two String parameters representing the prefix and suffix of and creates a temp file with specified details.

The createDirectory() method of the Files class accepts the path of the required directory and creates a new directory.

Example

Following example creates a new directory using the createDirectory() method of the Files class.

Live Demo

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class Test {
   public static void main(String args[]) throws IOException {
      //Creating a path object
      String pathStr = "D:\sample_directory ";  
      Path path = Paths.get(pathStr);      
      //Creating a directory
      Files.createDirectory(path);      
      System.out.println("Directory created successfully");
   }
}

Output

Directory created successfully

If you verify, you can observe see the created directory as −

Listing contents of a directory

The newDirectoryStream() method of the Files class opens the directory in the given path and returns the directory stream which gives the contents of the directory.

Example

import java.io.IOException;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class FilesExample {
   public static void main(String args[]) throws IOException {
      //Creating a path object
      String pathStr = "D:\ExampleDirectory";  
      Path path = Paths.get(pathStr);
      System.out.println("Contents off the specified directory");
      DirectoryStream stream = Files.newDirectoryStream(path);
      for (Path file: stream) {
         System.out.println(file.getFileName());
      }
   }
}

Output

Contents off the specified directory
demo1.pdf
demo2.pdf
sample directory1
sample directory2
sample directory3
sample directory4
sample_jpeg1.jpg
sample_jpeg2.jpg
test
test1.docx
test2.docx

Using directory filters

You can filter the directory using the DirectoryStream.Filter following example filters the directories in the specified path.

Example

import java.io.IOException;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class Test {
   public static void main(String args[]) throws IOException {
      //Creating a path object
      String pathStr = "D:\ExampleDirectory";  
      Path path = Paths.get(pathStr);
      System.out.println("Directories in the specified directory");      
      DirectoryStream.Filter filter = new DirectoryStream.Filter(){
         public boolean accept(Path file) throws IOException {
            return (Files.isDirectory(file));
         }
      };        
      DirectoryStream list = Files.newDirectoryStream(path, filter);
      for (Path file : list) {
         System.out.println(file.getFileName());
      }
   }
}

Output

Directories in the specified directory
hidden directory1
hidden directory2
sample directory1