如何读取用户在Java中的输入并将其写入文件 [英] How to read from user's input in Java and write it to a file

问题描述

我想创建一个简单的独立应用程序，它将从用户（某些数字和数学函数f（x，y ...））中获取一些输入，并将它们写入文件。然后在这个文件的帮助下，我将运行一个命令。

我需要的基本成分：

- - 为用户输入的JTextArea。
$ b - ButtonHandler / ActionListener并将输入写入（txt）文件

<执行命令ButtonHandler / ActionLister

最好的方法是什么？

当前正在运行的代码（基本上是一个玩具） - 不写任何东西，只是执行 - 是：
$ b $ pre $ import java .applet *。
import java.lang。*;
import javax.swing。*;
import java.awt。*;
import java.awt.event。*;
import java.awt.Dialog;
import java.io.IOException;
import java.io.InputStream;
import java.io. *;
import java.util。*;
import java.io.BufferedWriter;

public class Runcommand3
{
public static void main（String [] args）throws FileNotFoundException，IOException
{
// JApplet applet = new JApplet （）;
//applet.init（）;

final JFrame frame = new JFrame（Change Backlight）;
frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;

JPanel panel = new JPanel（）;
panel.setLayout（null）;
frame.add（panel）;
JButton button = new JButton（Click me to Run）;
button.setBounds（55,100,160,30）;
panel.add（button）;

frame.setSize（260,180）;
frame.setVisible（true）;
//这是一个Action Listener，它响应点击按钮
button.addActionListener（new ButtonHandler（））;


class ButtonHandler实现ActionListener {
public void actionPerformed（ActionEvent event）{
double value = Double.parseDouble（
JOptionPane.showInputDialog 请输入背光值））;
// File theFile = new File（thisfile.txt）;
//theFile.write（valueue）;
String command =xbacklight -set+ value;
try {Runtime run = Runtime.getRuntime（）;
Process pr = run.exec（command）;}
catch（IOException t）{t.printStackTrace（）;}
}
}


$ b

在上面的例子中，我怎样才能将值写入文件？那么，如何添加更多的输入（更多的文本框）呢？我可以在同一班上做，还是需要更多？
我的困惑来自于ButtonHandler类中我不能定义任何其他对象（即打开和写入文件等）的事实（主要但不仅仅是）。

解决方案

这是我写入文件的方式。我会让你把这个代码转换成你的GUI来练习。有关 BufferedWriter 和 FileWriter

  import java.io.BufferedWriter; 
 import java.io.FileWriter; 
 import java.util.Scanner; 
 $ b $ public class File {
 
 public static void main（String args []）{
 
 System.out.print（Enter Text： ）; 
扫描仪扫描=新扫描仪（System.in）; 
 String text = scan.nextLine（）; 
 FileWriter fWriter = null; 
 BufferedWriter writer = null; 
尝试{
 fWriter = new FileWriter（text.txt）; 
 writer = new BufferedWriter（fWriter）; 
 writer.write（text）; 
 writer.newLine（）; 
 writer.close（）; 
 System.err.println（您输入的+ text.length（）+字符已保存。）; 
 catch（Exception e）{
 System.out.println（Error！）; 
} 
} 
 
} 
  

I want to create a simple stand-alone application that will take some input from user (some numbers and mathematical functions f(x,y...)) and write them to a file. Then with the help of this file I will run a command.

Basic ingredients that I need:

-- JTextArea for users input.

-- ButtonHandler/ActionListener and writing of the input to a (txt) file

-- ButtonHandler/ActionLister to execute a command

What is the best way to do it?

A current running code that I have (basically a toy) - which does not write anything, just executes - is:

import java.applet.*;
import java.lang.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.Dialog;
import java.io.IOException;
import java.io.InputStream;
import java.io.*;
import java.util.*;
import java.io.BufferedWriter;

public class Runcommand3
{
  public static void main(String[] args) throws FileNotFoundException, IOException
  {
    //JApplet applet = new JApplet();
    //applet.init();

    final JFrame frame = new JFrame("Change Backlight");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel();
    panel.setLayout(null);
    frame.add(panel);
    JButton button = new JButton("Click me to Run");
    button.setBounds(55,100,160,30);
    panel.add(button);

    frame.setSize(260,180);
    frame.setVisible(true);
    //This is an Action Listener which reacts to clicking on the button
    button.addActionListener(new ButtonHandler());
  }
}
 class ButtonHandler implements ActionListener{
                public void actionPerformed(ActionEvent event){
                double value = Double.parseDouble(
                JOptionPane.showInputDialog("please enter backlight value"));
                //File theFile = new File("thisfile.txt");
                //theFile.write(value);
                String command = "xbacklight -set " + value;
                try{Runtime run = Runtime.getRuntime();
                Process pr = run.exec(command);}
                catch(IOException t){t.printStackTrace();}
                  }
                }

In the above example how can I write 'value' to a file? Then, how can I add more input (more textfields)? Can I do it in the same class or I need more? My confusion comes (mainly but not only) from the fact that inside the ButtonHandler class I can NOT define any other objects (ie, open and write files etc).

解决方案

This is the way I would write to a file. I will let you convert this code into your GUI for practice. See more on BufferedWriter and FileWriter

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.util.Scanner;

public class Files {

    public static void main(String args[]){

        System.out.print("Enter Text: ");
        Scanner scan = new Scanner(System.in);
        String text = scan.nextLine();
        FileWriter fWriter = null;
        BufferedWriter writer = null;
        try {
          fWriter = new FileWriter("text.txt");
          writer = new BufferedWriter(fWriter);
          writer.write(text);
          writer.newLine();
          writer.close();
          System.err.println("Your input of " + text.length() + " characters was saved.");
        } catch (Exception e) {
            System.out.println("Error!");
        }
    }

}

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