Question

我是Java的新手。我编写了一个程序，用以下格式创建4个json对象。

{"hostname":"host1","username":"user1"}
{"hostname":"host2","username":"user2"}
{"hostname":"host3","username":"user3"}
{"hostname":"host4","username":"user4"}

我使用两个输入文件hosts.lst和users.lst并将它们存储在一个arraylist中

$ cat hosts.lst
host1
host2
host3
host4
$ cat users.lst
user1
user2
user3
user4

现在我想要主机＆lt; \ n＆gt;在＆＃34; 1到4＆＃34;的范围内;但用户＆lt; \ n＆gt;不应超过＆＃34; 2＆＃34;。我无法使用嵌套for循环（我最终创建4 * 2 = 8个对象）。如何控制多个计数器并将它们增加到不同的级别。我希望最终输出看起来像：

{"hostname":"host1","username":"user1"}
{"hostname":"host2","username":"user2"}
{"hostname":"host3","username":"user1"}
{"hostname":"host4","username":"user2"}

一旦用户计数器达到2，它应该从1重新启动。

这是我的代码：

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

import org.json.simple.JSONObject;

public class JsonGenerator {

private static ArrayList<String> users = new ArrayList<String>();
private static ArrayList<String> hosts = new ArrayList<String>();

public static void arrayListConstructor1(String filename) throws IOException {
    BufferedReader br = null;
    br = new BufferedReader(new FileReader(filename));
    String line = br.readLine();
    while (line != null) {
        users.add(line);
        line = br.readLine();
    }
    br.close();
}

public static void arrayListConstructor2(String filename) throws IOException {
    BufferedReader br = null;
    br = new BufferedReader(new FileReader(filename));
    String line = br.readLine();
    while (line != null) {
        hosts.add(line);
        line = br.readLine();
    }
    br.close();
}

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

    for (int counter = 0; counter < 4; counter++) {

        arrayListConstructor1("e:\\users.lst");
        arrayListConstructor2("e:\\hosts.lst");

        String hostname = new String(hosts.get(counter));
        String username = new String(users.get(counter));

        JSONObject obj = new JSONObject();

        obj.put("hostname", hostname);
        obj.put("username", username);

        System.out.print(obj);
        System.out.println("\n");

    }
}}

我感谢任何帮助。谢谢！

Answer 1

您可以尝试以下代码..我们将计数器的模数改为2并加1 ..因此，对于增加的计数器值，该值将在1和2之间循环。

String username = new String(users.get((counter % 2) + 1));

另一种方法是将限制传递给从文件读取用户的方法，然后该方法只能读取所需数量的用户。

arrayListConstructor1("e:\\users.lst", 2);

Answer 2

就像现在一样，你的代码正在4次读取2个文件，你应该在循环之前移动arrayListConstructor1(...)和arrayListConstructor2(...)，只读一次。此外，这种方法似乎做同样的事情，你只能有一种方法来读取文件。要限制用户列表的范围，您可以定义第二个计数器，并在每次达到最大范围时将其设置为0。这是一个例子：

public static ArrayList<String> arrayListConstructor(String filename) throws IOException {
    ArrayList<String> list = new ArrayList<String>();
    try (BufferedReader br = new BufferedReader(new FileReader(filename));) {
        for (String line; (line = br.readLine()) != null) {
            list.add(line);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return list;
}


public static void main(String[] args) {

    ArrayList<String> hosts = arrayListConstructor("e:\\\\hosts.lst");
    ArrayList<String> users = arrayListConstructor("e:\\\\users.lst");
    JSONArray arr = new JSONArray();

    for (int counter = 0, counter2 = 0; counter < hosts.size() && users.size() >= 2; counter++, counter2++) {
        String hostname = hosts.get(counter);
        String username = users.get(counter2);
        if (counter2 == 1) {
            counter2 = 0;
        }

        JSONObject obj = new JSONObject();

        obj.put("hostname", hostname);
        obj.put("username", username);
        arr.put(obj);

        System.out.print(obj);
        System.out.println("\n");

    }
    System.out.print(arr);
}

循环使用多个计数器

2 个答案: