AsyncTask 致命错误 #1

Question

运行此代码时发生异步致命错误。

我正在制作一个应用程序，它将像 Team viewer 一样控制远程计算机。

package pk.edu.cust.fyp.nobeen.sameer.umair.pccontroller;

import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.Socket;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class MainActivity extends AppCompatActivity {


    Button connectBtn;
    EditText ipAddressEditTxt;
    String ipAddress;
    int port=4444;
    boolean connectionResult = false;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        connectBtn = (Button) findViewById(R.id.connect);
        ipAddressEditTxt = (EditText) findViewById(R.id.ipEditText);
        ipAddress = ipAddressEditTxt.getText().toString();


        connectBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {             
                ClientConnection clientConnection = new ClientConnection();
              clientConnection.execute(ipAddress);
              if(connectionResult == true) {

                  Toast.makeText(getApplicationContext(),"Success", Toast.LENGTH_SHORT).show();

                  Intent intent;
                    intent = new Intent(MainActivity.this, Login.class);
                    startActivity(intent);

                }
                else
                    Toast.makeText(getApplicationContext(),"Connection Failed",Toast.LENGTH_SHORT).show();
            }
        });

    }
     class ClientConnection extends AsyncTask <String,String,String>
    {
        Socket socket;
        DataInputStream dataInputStream;
        DataOutputStream dataOutputStream;
        Context context;
        String TAG ="Client Connection";

        @Override
        protected String doInBackground(String... params) {
            Toast.makeText(getApplicationContext(),"doInBackground run", Toast.LENGTH_SHORT).show();

            try {

                socket = new Socket(params.toString(), port);

                dataInputStream = new DataInputStream(socket.getInputStream());
                dataOutputStream = new DataOutputStream(socket.getOutputStream());
                Toast.makeText(getApplicationContext(),"Connection is succesfully "+dataInputStream.readUTF(),Toast.LENGTH_SHORT).show();
                if(socket.isConnected())
                {
                    connectionResult=true;
                }
            }catch (Exception ex)
            {
                Toast.makeText(getApplicationContext(),"Exception occur: "+ex,Toast.LENGTH_SHORT).show();
                //Log.e(TAG,ex.toString());
                connectionResult = false;
            }
            return null;
        }
        protected  void onPreExecute()
        {
          super.onPreExecute();
        }
        protected void onPostExecute(String s){
            Toast.makeText(getApplicationContext(),"OnPost"+connectionResult,Toast.LENGTH_SHORT).show();
            //super.onPostExecute(s);
        }
    }

   }

Answer 1

问题：您在后台显示 Toast，但未运行 UI 线程。从 doInBackground() 方法中删除两个 Toast 消息

如果您想显示 toast，请在 onPreExecute() 和 onPostExecute() 方法中显示它们，因为它们是在 UI 线程中调用的，但 doInBackground() 是在单独的线程中调用的。