Question

我想编写存储汽车信息的程序。您可以在对话框中输入每辆车的品牌和所有者名称。最后，通过将信息写入文本文件，然后从中读取到对话框，可以显示包含所有汽车信息的对话框。我创建了一个方法getInfo，它正确地显示了相应的框。

public static void getInfo() {
  boolean done = false;
  do {
     String brand=JOptionPane.showInputDialog(null, "Brand?");
     String name=JOptionPane.showInputDialog(null, "Owner?");

     if (brand == null) {
        done = true;

     } else {
        String info ="Car: "+brand+" "+"\nOwner: "+name;
        String message =  " Do you want to input more cars?";
        int buttonClicked = JOptionPane.showConfirmDialog(null,      message, "", JOptionPane.YES_NO_OPTION);
        done = (buttonClicked == JOptionPane.NO_OPTION);

     }
    } while (!done);
}

public static void main(String[] args) {
  getInfo();
}

我不确定如何将信息添加到文本文件以及如何处理循环。要将信息写入文本文件，我尝试将main方法更改为以下

public static void main(String[] args) throws IOException {

    try (PrintWriter outstream = new PrintWriter
                             (new BufferedWriter
                             (new FileWriter("cars.txt", true)))) {
       getInfo();
       outstream.println(info);
    }
}

我缺少什么以及如何实现这些功能？

Answer 1

您可以在循环外定义$email_id = $_GET['id']; $result = $con->prepare("SELECT * FROM bike_showroom JOIN car_showroom JOIN coaching JOIN college JOIN electronic JOIN furniture_showroom JOIN hospital JOIN job JOIN mobile_shop JOIN pets_shops JOIN play_school JOIN real_estate JOIN services JOIN shopping_store JOIN stationary_shops JOIN sweet_shop WHERE bike_showroom.ad_id = '".$email_id. "' AND car_showroom.ad_id = '".$email_id. "' AND coaching.ad_id = '".$email_id. "' AND college.ad_id = '".$email_id. "' AND electronic.ad_id = '".$email_id. "' AND furniture_showroom.ad_id = '".$email_id. "' AND hospital.ad_id = '".$email_id. "' AND job.ad_id = '".$email_id. "' AND mobile_shop.ad_id = '".$email_id. "' AND pets_shops.ad_id = '".$email_id. "' AND play_school.ad_id = '".$email_id. "' AND real_estate.ad_id = '".$email_id. "' AND services.ad_id = '".$email_id. "' AND shopping_store.ad_id = '".$email_id. "' AND stationary_shops.ad_id = '".$email_id. "' AND sweet_shop.ad_id = '".$email_id."' "); $result->execute(); $row = $result->fetch(); for($i=0; $row = $result->fetch(); $i++){ echo $row['title']; }：

BufferedWriter

然后在你的循环中：

之后

File outputFile = new File("path/to/the/file.txt");
if(!outputFile.exists()){
    try {
        outputFile.createNewFile();
    } catch (IOException e) {
        e.printStackTrace();
    }
}
BufferedWriter bw = null; //this declares a buffer that writes to some stream. 
try{
    bw = new BufferedWriter(new FileWriter(outputFile,true));    //here we actually create it, and tell it to write to a file stream, directed at the outputFile file.
}catch(IOException e){
    e.printStackTrace(); //this is if the file doesn't exist, which shouldn't happen, but we still need to put this here, because better safe than sorry.
}

做的：

String info ="Car: "+brand+" "+"\nOwner: "+name;

退出循环后，请致电：

String info ="Car: "+brand+" "+"\nOwner: "+name;


try {
    bw.write(info);//write the information to the buffer when there's new info. 
    bw.newLine();
} catch (IOException e) {
    e.printStackTrace();
}

Answer 2

首先，对于每个循环，您正在创建info的新实例，因此您将丢失先前运行的信息。

在您的main方法中，您正在访问info，但在该范围内不应该知道它。您可以做的是从info方法返回getInfo()。

你应该考虑换行等等，但是第一次尝试应该是它。

Answer 3

尝试以下方法：

public static void main() {
  boolean done = false;
  do {
    Info info = getInfo();
    storeInfo(info);
    done = getDone();
  } while (!done);

  displayInfo();
}

class Info {
  private brand;
  private owner;
}

现在你可以在每种方法中单独做一些事情。

getInfo调用showInputDialog并返回一个Info对象。

storeInfo将Info对象存储到文本文件中。

getDone调用showInputDialog并返回，如果用户想要退出。

displayInfo打开文本文件并显示信息。

实现displayInfo migth的最简单方法是：

void displayInfo() {
  // Create a window with TextBox
  // Open the text file
  // Read the content of the text file and add it to the TextBox
}

将对话框中的信息存储到文本文件Java中

3 个答案: