如何使用Java创建的“使用键盘和PrintWriter类”写入txt文件

Question

I created a method for writing to a file but the method could not execute as I called it in the main method. I also want to find what to know if I can write to the file via keyboard instead of using the PrintWriter resource?

import java.io.*;
import java.util.*;
/**
 *
 * @author toshiba
 */
public  class EXERISESONFILEWRITINGANDREADING {
        File file;

    public static void main(String[] args) throws Exception{
        EXERISESONFILEWRITINGANDREADING obj = new   EXERISESONFILEWRITINGANDREADING();
        obj.Create("D:\\document\\work.txt");
        obj.Write();
        obj.Read();
        }

    public  void Create(String name){ //name implies the directory of your  folder/file.
         file = new File(name); 
    }

    public void Write() throws Exception{
        PrintWriter WRITE = new PrintWriter(file);
        WRITE.print("this is my abode");
        WRITE.print("\nthis is my apartment");
        WRITE.print("\nthis is my Private Jet");
    }
    public void Read() throws Exception{
        Scanner input = new Scanner(file);
        while(input.hasNext()){
            System.out.println(input.next());
        }
    }

Answer 1

Your code is not executing because, you are not flushing your PrintWriter resource in your write method. Your write method will write to a given file you change it to this:

public void write() throws Exception {
    PrintWriter writer = new PrintWriter(file);
    writer.println("this is my abode");
    writer.println("this is my apartment");
    writer.println("this is my Private Jet");

    writer.flush();
    writer.close();
}

Now, if you want to accept inputs from keyboard and then write it to file, you can make use of Scanner .

Create a Scanner with System.in as InputStream :

Scanner sc = new Scanner(System.in);

Create or use your same PrintWriter resource:

PrintWriter writer = new PrintWriter(file);

Start accepting the inputs from the keyboard until the user gives in a blank line - "" and write it to your file.

String in = "";
while ( !(in = sc.nextLine()).equals("") ) {
    writer.println(in);
}

And finally, the entire method should look like:

public void writeToFileFromKeyboard() throws FileNotFoundException {
    Scanner sc = new Scanner(System.in);
    PrintWriter writer = new PrintWriter(file);

    String in = "";
    while ( !(in = sc.nextLine()).equals("") ) {
        writer.println(in);
    }

    sc.close();
    writer.flush();
    writer.close();
}

Note: This is just a suggestion!!

If you are using Java-8 , you can modify your read() method to make use of Java-8 Streams, so that your method becomes more declarative in nature . Hence, the modified read() method looks like:

public void read() throws Exception {
    Files.lines( Paths.get(filePath) )
         .forEach( System.out::println );
}