This includes support for common operations like creating, reading from and writing to files; copy-pasting content between them; appending new information or deleting it completely - making these an ideal choice when dealing with complex file system tasks. 

The most important classes for working with files in Java are 

• File: This class represents a file or directory on the file system. You can use it to perform operations such as creating, deleting, and renaming files. 
• FileReader and FileWriter: These classes provide a way to read and write text data to a file.
• InputStream and OutputStream: These classes provide a way to read and write binary data to a file. 

The following code creates a new file called "example.txt" and writes the text "Hello, World!" to it: 

File file = new File("example.txt"); 
FileWriter writer = new FileWriter(file); 
writer.write("Hello, World!"); 
writer.close(); 

Similarly, the following code reads the text from the file "example.txt" and prints it to the console: 

FileReader reader = new FileReader(file); 
int c; 
while((c = reader. read()) != -1) { 
System.out.print((char)c); 
} 
reader.close(); 
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It will print "Hello, World!"