java - 从 ArrayList 填充微调器时出现问题

Question

我有一个 ArrayList，其中包含从文本文件读取的字符串。我希望这些字符串填充微调器，但我的代码不起作用，当我将鼠标悬停在该行上时，它显示“无法解析构造函数”:

ArrayAdapter adp = new ArrayAdapter(this, android.R.layout.simple_spinner_item, devicesAL);

这是我的其余代码，我已经提供了所有代码，因为我不知道原因在哪里。该特定位位于第二个 try block 中。有人可以帮忙吗？

package com.example.iotdevicestatus;


public class MainActivity extends AppCompatActivity {

    String statusLink = "http://redacted.uk/pmt/status.txt";
    String deviceLink = "http://redacted.uk/pmt/devices.txt";
    String status = "status testttest";

    ArrayList<String> devicesAL = new ArrayList<>();



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Thread thread = new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    // Set up connection to device.txt on web server
                    URL deviceUrl = new URL (deviceLink);
                    URLConnection deviceConn = deviceUrl.openConnection();
                    deviceConn.setDoOutput(true);
                    deviceConn.connect();

                    InputStream dis = deviceConn.getInputStream();
                    InputStreamReader disr = new InputStreamReader(dis, "UTF-8");
                    BufferedReader dbr = new BufferedReader(disr);

                    String deviceLine;

                    // Set up connection to status.txt on web server
                    URL statusUrl = new URL(statusLink);
                    URLConnection statusConn = statusUrl.openConnection();
                    statusConn.setDoOutput(true);
                    statusConn.connect();

                    InputStream sis = statusConn.getInputStream();
                    InputStreamReader sisr = new InputStreamReader(sis, "UTF-8");
                    BufferedReader sbr = new BufferedReader(sisr);

                    String statusLine;


                    try {

                        while ((deviceLine = dbr.readLine()) != null) {
                            System.out.println(deviceLine);
                            devicesAL.add(deviceLine);

                            Spinner spinner = (Spinner) findViewById(R.id.spinner);
                            ArrayAdapter adp = new ArrayAdapter(this, android.R.layout.simple_spinner_item, devicesAL);
                            adp.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                            spinner.setAdapter(adp);
                        }

                        while ((statusLine = sbr.readLine()) != null) {
                            System.out.println(statusLine);
                            status = statusLine;

                            System.out.println("Status = " + status);
                            //al.add(line); - use in case of multiple statuses

                            TextView output = (TextView) findViewById(R.id.textView);

                            System.out.println(status);

                            output.setText(status);
                        }


                        for (String str : devicesAL) {
                            System.out.println(str);
                        }


                    } finally {
                        sbr.close();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        thread.start();



    }
}

Answer 1

请注意，匿名类中的 this 引用该匿名类。您想要的是 MainActivity 的实例，而不是 Runnable 匿名子类的实例。

ArrayAdapter adp = new ArrayAdapter(MainActivity.this, android.R.layout.simple_spinner_item, devicesAL);

<小时/>

由于您的 Spinner 尚未填充，您可以

1. 确保已填充 devicesAL
2. 在将适配器填充并设置为 Spinner 后调用 adp.notifyDataSetChanged()。
3. 在 Activity#runOnUiThread() 中运行与修改 UI 相关的所有内容。