Android tcp/ip 读写缓冲区脱离主代码

Posted 2023-04-19

【中文标题】Android tcp/ip 读写缓冲区脱离主代码

【英文标题】：Android tcp/ip read and write buffer out of main code

【发布时间】：2017-07-10 01:50:27

【问题描述】：

我可以通过一个按钮在 Main 布局和 MainActivity java 上读写 TCP/IP 缓冲区。

但不能在不同的片段或不同的布局上这样做。

错误信息是：

java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“void com.example.murat.ev.TcpClient.sendMessage(java.lang.String)”

我的代码：

MainActivity.java

public class MainActivity extends AppCompatActivity 
public TcpClient mTcpClient;
public Thread send_data;
public Button button;
public byte data[]=new byte[1024];

public DatabaseConstruction db;

@Override
protected void onCreate(Bundle savedInstanceState)

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    db = new DatabaseConstruction(getApplicationContext());
    new datasync().execute("");

    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    Fragment1 fragment1=new Fragment1();
    fragmentTransaction.replace(R.id.container, fragmen1_layout);
    fragmentTransaction.commit();

    button=(Button)findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() 
        @Override
        public void onClick(View v) 
            send_data_pre();
        
    );


public class datasync extends AsyncTask<String, String, TcpClient>

    @Override
    protected TcpClient doInBackground(String... message)
    
        //we create a TCPClient object and
        mTcpClient = new TcpClient(new TcpClient.OnMessageReceived()
        
            @Override
            //here the messageReceived method is implemented
            public void messageReceived(String message)
            
                Log.i("Debug","Input message: " + message);
                publishProgress(message);
            
        );

        mTcpClient.run();
        return null;
    

    @Override
    protected void onProgressUpdate(String... values)
    
        super.onProgressUpdate(values);
        Log.i("onProgressUpdate",values[0]);
    



public void send_data_pre()

    send_data = new Thread(new send_data("hello"));
    send_data.start();


public class send_data implements Runnable

    private String message;
    public send_data (String message)
    
        this.message = message;
    
    @Override
    public void run()
    
        mTcpClient.sendMessage(message);
        Log.i("Debug", "mesaj did send");
    
  

Fragment1.java

public class Fragment1 extends Fragment 
Button button1;
MainActivity main=new MainActivity();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)

    View view = inflater.inflate(R.layout.fragment1_layout, container, false);
    button1 =(Button)view.findViewById(R.id.buton_1);
    button1.setOnClickListener(new View.OnClickListener() 
        @Override
        public void onClick(View v) 
            main.send_data();   ////THIS HERE IS APP STOP AND ERROR
        
    );
    return view;
  

【参考方案1】：

也许在你想要做的片段中 main.send_data_pre();insted main.send_data(); 如果我很好地理解了您的问题，就像您在 MainActivity 的 OnCreate() 中所做的那样。