java - 用全大写、小写和反向java将字符串打印到文件中

Question

我需要在代码中输入一行文本，并让它以全大写、全小写和反向的方式将该文本打印到文件中。我知道如何使用字符串执行此操作，但无法弄清楚如何让它以这种方式打印到文件。我不需要帮助在输出中打印文本，而是让它以所有这些方式打印到实际的 PrintToFile.txt，而不需要实际输入所有这些不同的方式。

import java.io.FileNotFoundException;
import java.lang.SecurityException;
import java.util.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class PrintToFile { //open class 

private static Formatter output;

public static void main (String args[]) throws IOException { //open main     
openFile();
addRecords();
closeFile();

BufferedReader printFile = new BufferedReader(new FileReader("YoastReginaITM251Project9.txt"));

for (String line; (line = printFile.readLine()) != null;) { //open for 
  System.out.println("Text: " + line);
  System.out.println("Text in Upper Case: " + line.toUpperCase());
  System.out.println("Text in Lower Case: " + line.toLowerCase());
  System.out.println("Text in Reverse Case: " + line);
} //close for

} //close main 

public static void openFile() { //open openFile

try { //open try 
  output = new Formatter("PrintToFile.txt"); //open file 
} //close try 

 catch (SecurityException securityException) { //open catch 
  System.err.println("Write permission denied. Terminating.");
  System.exit(1);
} //close catch 

catch (FileNotFoundException fileNotFoundException) { //open catch 
  System.err.println("Error opening file. Terminating.");
  System.exit(1);
} //close catch 

} //close openFile

public static void addRecords() { //open addRecords 


  try { //open try 
    output.format("%s", input.nextLine()); 
  } //close try 
  catch (FormatterClosedException formatterClosedException) { //open catch 
    System.err.println("Error writing to file. Terminating.");
  } //close catch 
  catch (NoSuchElementException elementExpcetion) { //open catch 
    System.err.println("Invalid input. Please try again.");
    input.nextLine(); 
  } //close catch 


  } //close AddRecords 

 public static void closeFile() { //open closeFile 

  if (output != null)
  output.close();

  } //close closeFile   

 } //close class  

Answer 1

    String input = "MagicString";

    String upperCase = input.toUpperCase();
    String lowerCase = input.toLowerCase();

    StringBuilder sb = new StringBuilder();
    sb.append(input);

    String reversedString = sb.reverse().toString();