文件 reading/writing 正确顺序

Question

所以我正在开发这个程序，它需要创建一个文件，写入该文件，然后从该文件中读取。但是，该文件并未被写入，而是仍在创建中。首先，这是我的文件中构造函数的声明，用于执行 class（称为 filer）：

private static FileWriter fw;
private static FileReader fr;
private static BufferedWriter bw;
private static BufferedReader br;

mainclass的main方法首先执行这个openFile()方法，它在filerclass中。这是 openFile():

public static void openFile() {
    try{ //exception handling
        file = new File("jibberish.txt");
        fw = new FileWriter(file); //dont put filewriter or buffedwriter before these, because already declared and end up
        bw = new BufferedWriter(fw);  //making null expection thing
        fr = new FileReader(file);
        br = new BufferedReader(fr);
    }catch(IOException ioe){ 
        System.out.println("Trouble reading from the file: " + ioe.getMessage());
    }
}

现在在 main 方法中，我设置了一个面板，该面板在另一个连接的 class 上都可以正常工作。有一个 jTextField 接受用户输入的内容，并通过这个 class 运行它，这是我似乎无法实际写入文件的地方。

 public static void addStuff(String toAdd){ 
    String line = "";
    try {
        bw.write(toAdd);
        //bw.newLine();
        System.out.println(toAdd + " added");
        //line = br.readLine();
         while((line = br.readLine()) != null) {
                System.out.println(line + "r");
            }
    } catch (IOException e) {               
        e.printStackTrace();
        System.out.println("Error at addstuff");
    }
}

所以我需要程序做的，它现在没有做的，实际上是写入文件并能够读取它。提前致谢！

Answer 1

我不确定真正的问题是什么，因为我只是做了你刚才做的并且对我有用：

这里是完整的 class 代码：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;

import org.apache.poi.xslf.model.geom.AddSubtractExpression;

public class a {

    private static FileWriter fw;
    private static FileReader fr;
    private static BufferedWriter bw;
    private static BufferedReader br;
    static File file;

    public static void openFile() {
        try{ //exception handling
            file = new File("jibberish.txt");
            fw = new FileWriter(file); //dont put filewriter or buffedwriter before these, because already declared and end up
            bw = new BufferedWriter(fw);  //making null expection thing
            fr = new FileReader(file);
            br = new BufferedReader(fr);
        }catch(Exception ioe){ 
            System.out.println("Trouble reading from the file: " + ioe.getMessage());
        }
    }


    public static void addStuff(String toAdd){ 
        String line = "";

        try {
            bw.write(toAdd);
            //bw.newLine();
            System.out.println(toAdd + " added");
            //line = br.readLine();
             while((line = br.readLine()) != null) {
                    System.out.println(line + "r");
                }
        } catch (Exception e) {               
            e.printStackTrace();
            System.out.println("Error at addstuff");
        }
    }


    public static void main(String... args){
        openFile();
        int i=0;
        while(true)
            addStuff("hello" + i++);
    }
}

Answer 2

一定要加上

bw.flush();

在写入后刷新缓冲区并将数据放入文件以便能够读回您的代码。

文件 reading/writing 正确顺序

File reading/writing proper order

java

file

bufferedwriter

bufferedreader