protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ipEditText = findViewById(R.id.ipEditText); portEditText = findViewById(R.id.portEditText); Button connectButton = findViewById(R.id.connectButton); connectButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String ip = ipEditText.getText().toString(); int port = Integer.parseInt(portEditText.getText().toString()); new ConnectTask().execute(ip, String.valueOf(port)); } }); Button sendMessageButton = findViewById(R.id.sendMessageButton); sendMessageButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { showSendMessageDialog(); } }); } private class ConnectTask extends AsyncTask<String, Void, Void> { @Override protected Void doInBackground(String... params) { String ip = params[0]; int port = Integer.parseInt(params[1]); try { socket = new Socket(ip, port); in = new BufferedReader(new InputStreamReader(socket.getInputStream())); out = new PrintWriter(socket.getOutputStream(), true); // 在 UI 线程中创建 SeekBar handler.post(new Runnable() { @Override public void run() { SeekBar progressBar = findViewById(R.id.progressBar); progressBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { // 计算百分比对应的数字 int number = progress * 10; // 在 UI 线程中更新 ProgressBar 的进度 handler.post(new Runnable() { @Override public void run() { seekBar.setProgress(number); } }); out.println(number); } @Override public void onStartTrackingTouch(SeekBar seekBar) {} @Override public void onStopTrackingTouch(SeekBar seekBar) {} }); } }); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return null; } @Override protected void onPostExecute(Void aVoid) { // 在连接结束后做一些处理 // 比如关闭连接或者显示连接成功的提示 } }代码修改

这段代码中的 `ConnectTask` 使用了 `AsyncTask` 机制，将网络连接和数据读取操作放在了后台线程中，但是在 `doInBackground` 方法中创建了 UI 控件 `SeekBar`，并在其中更新了 UI，这是不允许的。正确的做法是将 `SeekBar` 的创建和更新放在 `onPostExecute` 方法中。修改后的代码如下：

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

    ipEditText = findViewById(R.id.ipEditText);
    portEditText = findViewById(R.id.portEditText);

    Button connectButton = findViewById(R.id.connectButton);
    connectButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String ip = ipEditText.getText().toString();
            int port = Integer.parseInt(portEditText.getText().toString());
            new ConnectTask().execute(ip, String.valueOf(port));
        }
    });

    Button sendMessageButton = findViewById(R.id.sendMessageButton);
    sendMessageButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            showSendMessageDialog();
        }
    });
}

private class ConnectTask extends AsyncTask<String, Void, Void> {
    @Override
    protected Void doInBackground(String... params) {
        String ip = params[0];
        int port = Integer.parseInt(params[1]);
        try {
            socket = new Socket(ip, port);
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(), true);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        // 在连接结束后做一些处理
        // 比如关闭连接或者显示连接成功的提示
        SeekBar progressBar = findViewById(R.id.progressBar);
        progressBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                // 计算百分比对应的数字
                int number = progress * 10;
                out.println(number);
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {}

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {}
        });
    }
}