Question

代码是从文件中读取信息，使用该信息创建对象，然后将其添加到名为servers的ArrayList中。

    try {
        BufferedReader br = new BufferedReader(new InputStreamReader(openFileInput(MainActivity.FILE_SERVERS)));
        String line = "";
        while ((line = br.readLine()) != null) {
            String name = "";
            String ip = "";
            String port = "";
            String checkFrequency = "";
            int counter = 1;
            boolean alert = true;
            for (String value : line.split(",")){
                if (counter == 1){
                    name = value;
                }else if (counter == 2){
                    ip = value;
                }else if (counter == 3){
                    port = value;
                }else if (counter == 4){
                    checkFrequency = value;
                }else if (counter == 5){
                    alert = Boolean.parseBoolean(value);
                }
                counter++;
            }           
            MCServer server = new MCServer(name, ip, port, checkFrequency, alert);
            servers.add(server);
        }
        br.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

存储在文件中的示例行：

Name,199.99.99.99,80,60,true

是否有更好的方法来检索该信息，以便能够将其存储在正确的变量中，而无需使用带有计数器的循环，如上所示？

Answer 1

怎么样：

try (BufferedReader br = new BufferedReader(
       new InputStreamReader(openFileInput(MainActivity.FILE_SERVERS)))) {
    String line = null;  // start with null in case there is no line
    while ((line = br.readLine()) != null) {
        String[] tokens = line.split(",");
        MCServer server = 
            new MCServer(tokens[0], tokens[1], tokens[2], tokens[3], 
              Boolean.parseBoolean(tokens[4]));
        servers.add(server);
    }
}

Answer 2

你可以忽略计数器并直接使用令牌，但你至少应该确定有足够的令牌：

try
{
  BufferedReader br = new BufferedReader(new InputStreamReader());
  String line = null;
  String[] tokens;
  while ((line = br.readLine()) != null) {
     tokens = line.split(",");
     MCServer test = new MCServer(tokens[0],tokens[1],tokens[2],tokens[3],Boolean.valueOf(tokens[4]));
  }
}
catch (IndexOutOfBoundsException e) { // <- be sure to catch this
  // not enough elements in array
}

此外，您将字符串作为IP地址和端口传递，它们是字符串，但应检查它们是否可以转换，因此您可以Integer.valueOf(tokens[2])例如只是为了引发NumberFormatException。

Answer 3

试试这个

 try {
    BufferedReader br = new BufferedReader(new InputStreamReader(openFileInput(MainActivity.FILE_SERVERS)));
    String line = "";
    while ((line = br.readLine()) != null) {
        String name = "";
        String ip = "";
        String port = "";
        String checkFrequency = "";
        int counter = 1;
        boolean alert = true;

        String s[] = line.split(",");
        name = s[0];
        ip = s[1];
        port = s[2];
        checkFrequency= s[3];
        alert = s[4];

        MCServer server = new MCServer(name, ip, port, checkFrequency, alert);
        servers.add(server);
    }
    br.close();
} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

Answer 4

我已经修改了你的代码：

try {
        BufferedReader br = new BufferedReader(new InputStreamReader(openFileInput(MainActivity.FILE_SERVERS)));
        String line;
        while ((line = br.readLine()) != null) {

            String[] lineSplitted = line.split(",");

            String name = lineSplitted[0];
            String ip = lineSplitted[1];
            String port = lineSplitted[2];
            String checkFrequency = lineSplitted[3];
            boolean alert = Boolean.parseBoolean(lineSplitted[4]);

            MCServer server = new MCServer(name, ip, port, checkFrequency, alert);
            servers.add(server);
        }
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

的变化：

初始化变量然后设置它们是多余的，如果没有事先设置它们就永远不会访问它们，所以如果你在第一个地方拆分你的线路，你可以立即用值初始化它们
循环
catch块可以折叠; IOException涵盖FileNotFoundException

是否有更清洁/更好的方式来写这个

4 个答案: