如何从文本文件中删除字符串？

Question

I'm working on creating simple address book using text file but my code is throwing too much errors in deleting a String method.It shows IO Exceptions at mostly places and when the IO Exceptions are resolved then compiling error cannot find symbol occurs at 5 places in some identifiers. Here is my code:

    public void DeletePerson(){    
      try {
         File file = new File("AddressBook.txt");
         File temp = File.createTempFile("file", ".txt", file.getParentFile()); 
         BufferedReader reader = new BufferedReader(new InputStreamReader(new 
           FileInputStream(file), Charset));

         PrintWriter writer = new PrintWriter(new OutputStreamWriter(new 
           FileOutputStream(temp), Charset));
         //More code ...
      } finally {
        if (writer != null) {
            System.out.println("Closing PrintWriter");
            writer.close(); 
        } else { 
            System.out.println("PrintWriter not open");
        }
        file.delete();
        temp.renameTo(file);
      }
    }

Output:

    C:\java\AddressBook>javac AddressBook.java
    
    AddressBook.java:50: error: cannot find symbol
    
        if (writer != null) {
            ^
      symbol:   variable writer
    
      location: class AddressBook
    
    AddressBook.java:52: error: cannot find symbol
    
            writer.close();
            ^
      symbol:   variable writer
    
      location: class AddressBook
    
    AddressBook.java:57: error: cannot find symbol
    
    file.delete();
    ^
      symbol:   variable file
    
      location: class AddressBook
    
    AddressBook.java:58: error: cannot find symbol
    
    temp.renameTo(file);
                  ^
      symbol:   variable file
    
      location: class AddressBook
    
    AddressBook.java:58: error: cannot find symbol
    
    temp.renameTo(file);
    ^
      symbol:   variable temp
    
      location: class AddressBook

I'm creating address-book and finding problem in deleting person's name method. Firstly i have to take input from user ie name of the person then i have to check the text-file(read the file) and find the matched word and then delete it from addressbook. I have also made other methods to delete the name but they didn't work thoroughly. Kindly check the code and resolve the problem please.

Answer 1

Your File and PrintWriter Object inside the try block
You can try to use it.

File file = new File("AddressBook.txt");
PrintWriter writer = new PrintWriter(new FileWriter(file,Charset.forName("UTF-8")));//use "throws IOException" in your method.
try{
//some java code
}finally{
    if (writer != null) { 
        System.out.println("Closing PrintWriter");
        writer.close(); 
    } else { 
        System.out.println("PrintWriter not open");
    } 
    file.delete();
}