android app crashes on client start

Question

I'm trying to make an app that connects to my tcp server on my pc to send text but every time I start the thread, my app crashes. please help. I just started using android studio so im not that familiar with it.

Here's my code:

package com.example.alex.hahanice;

import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Button;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class MainActivity extends AppCompatActivity {

    Handler UIHandler;

    Thread Thread1 = null;

    public static final int SERVERPORT = 6000;
    public static final String SERVERIP = "192.168.1.76";

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        this.Thread1 = new Thread(new Thread1());
        this.Thread1.start();

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

    public void onClick(View v) {
        View view;

        runOnUiThread(new Runnable() {
            public void run() {
                Thread1.start();
            }
        });
    }

    class Thread1 implements  Runnable
    {
        public void run() {
            Socket socket = null;

            try
            {
                InetAddress serverAddr = InetAddress.getByName(SERVERIP);
                socket = new Socket(serverAddr, SERVERPORT);

                Thread2 commThread = new Thread2(socket);
                new Thread(commThread).start();
            }
            catch(IOException e)
            {
                e.printStackTrace();
            }
        }
    }

    class Thread2 implements Runnable
    {
        private Socket clientSocket;

        private BufferedReader input;

        public Thread2(Socket clientSocket)
        {
            this.clientSocket = clientSocket;

            try
            {
                this.input = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
            }
            catch(IOException e)
            {
                e.printStackTrace();
            }
        }

        public void run()
        {
            while(!Thread.currentThread().isInterrupted())
            {
                try
                {
                    String read = input.readLine();
                    if(read != null)
                    {
                        //UIHandler.post(new updateUIThread(read));
                    }
                    else
                    {
                        Thread1 = new Thread(new Thread1());
                        Thread1.start();
                        return;
                    }
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
    }
}

Here's what the debugger says when I click on the button to start the thread to connect to my pc

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.example.alex.hahanice, PID: 3772
                  java.lang.IllegalStateException: Could not execute method for android:onClick
                      at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
                      at android.view.View.performClick(View.java:4659)
                      at android.view.View$PerformClick.run(View.java:19462)
                      at android.os.Handler.handleCallback(Handler.java:733)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:146)
                      at android.app.ActivityThread.main(ActivityThread.java:5692)
                      at java.lang.reflect.Method.invokeNative(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:515)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
                      at dalvik.system.NativeStart.main(Native Method)
                   Caused by: java.lang.reflect.InvocationTargetException
                      at java.lang.reflect.Method.invokeNative(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:515)
                      at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
                      at android.view.View.performClick(View.java:4659) 
                      at android.view.View$PerformClick.run(View.java:19462) 
                      at android.os.Handler.handleCallback(Handler.java:733) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:146) 
                      at android.app.ActivityThread.main(ActivityThread.java:5692) 
                      at java.lang.reflect.Method.invokeNative(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:515) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
                      at dalvik.system.NativeStart.main(Native Method) 
                   Caused by: java.lang.IllegalThreadStateException: Thread already started
                      at java.lang.Thread.checkNotStarted(Thread.java:871)
                      at java.lang.Thread.start(Thread.java:1025)
                      at com.example.alex.hahanice.MainActivity$1.run(MainActivity.java:50)
                      at android.app.Activity.runOnUiThread(Activity.java:5001)
                      at com.example.alex.hahanice.MainActivity.onClick(MainActivity.java:48)
                      at java.lang.reflect.Method.invokeNative(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:515) 
                      at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                      at android.view.View.performClick(View.java:4659) 
                      at android.view.View$PerformClick.run(View.java:19462) 
                      at android.os.Handler.handleCallback(Handler.java:733) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:146) 
                      at android.app.ActivityThread.main(ActivityThread.java:5692) 
                      at java.lang.reflect.Method.invokeNative(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:515) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
                      at dalvik.system.NativeStart.main(Native Method) 
Disconnected from the target VM, address: 'localhost:8600', transport: 'socket'

Answer 1

Your problem is on this line:

Thread Thread1 = null;

You are setting the thread to a null value and that's where it says the error is coming from. Try assigning it a different value and see if that changes anything.

Answer 2

You are starting Thread at onCreate()

this.Thread1 = new Thread(new Thread1());

this.Thread1.start();

Then again starting the same thread at onClick()