Application Force Closes On Startup

android sockets android-activity forceclose
chriswins2much picture chriswins2much · Apr 19, 2012 · Viewed 11.2k times · Source

Well, I am trying to make an app that communicates with a socket I have set up, tested, and made work in the background of a simple java application.

The problem is, my app keeps force closing right away. You don't get a chance to see anything before it fcs.

Here is my code:

import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Scanner;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.Toast;

public class LogMeInClientActivity extends Activity {
    private Socket s;
    private InetAddress hostIp, localIp;
    private final String hostName = "localhost";
    private final int port = 4000;
    private Scanner in;
    private PrintWriter out;
    private final EditText usernameField = (EditText)     findViewById(R.id.username_field),
            passwordField = (EditText) findViewById(R.id.password_field);
    private String username, password;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        System.out.println("A");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        System.out.println("B");
        try {
            hostIp = InetAddress.getByName(hostName);
            localIp = InetAddress.getLocalHost();
            System.out.println("Local Ip: " + localIp.toString());
            System.out.println("Host Ip: " + hostIp.toString());
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
        try {
            s = new Socket(hostIp, port);
            out = new PrintWriter(s.getOutputStream(), true);
            in = new Scanner(s.getInputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private class SignInButtonListener implements OnClickListener {

        public void onClick(View clickedButton) {
            switch (clickedButton.getId()) {
            case R.id.sign_in:
                username = usernameField.getText().toString();
                password = passwordField.getText().toString();
                if (username.length() != 0 && password.length() != 0) {
                    out.println(username);
                    out.println(password);
                }
                out.flush();
                break;

            default:
                break;
            }
        }
    }
}

In the above code, neither "A" or "B" prints out. The application simply fc's.

Here is my manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.chriswins2much.Util"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="15" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".LogMeInClientActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

I used the above permission, because I heard it would help for it.

I updated the code to fix for the EditText NullPointerException fix (Only changed parts):

private EditText usernameField, passwordField;
public void onCreate(Bundle savedInstanceState) {
        System.out.println("A");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        usernameField = (EditText) findViewById(R.id.username_field);
        passwordField = (EditText) findViewById(R.id.password_field);
        System.out.println("B");
        try {
                    // It's saying one of the errors are on line 37 (directly below)
            hostIp = InetAddress.getByName(hostName);
            localIp = InetAddress.getLocalHost();
            System.out.println("Local Ip: " + localIp.toString());
            System.out.println("Host Ip: " + hostIp.toString());
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
        try {
            s = new Socket(hostIp, port);
            out = new PrintWriter(s.getOutputStream(), true);
            in = new Scanner(s.getInputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

New logcat below:

04-19 02:46:56.292: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:57.049: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:46:57.103: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:57.450: E/dalvikvm(1289): Unable to open stack trace file '/data/anr/traces.txt': Permission denied
04-19 02:46:57.462: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:57.669: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:46:58.069: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:58.409: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:46:58.650: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:58.779: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:46:59.009: I/System.out(1289): A
04-19 02:46:59.153: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:59.321: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:46:59.639: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:46:59.879: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:00.249: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:00.490: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:00.819: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:00.970: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:01.279: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:01.477: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:01.791: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:01.919: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:02.302: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:02.443: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:02.811: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:02.999: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:03.409: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:03.583: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:03.870: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:04.029: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:04.410: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:04.529: I/System.out(1289): B
04-19 02:47:04.603: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:04.850: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:05.020: D/AndroidRuntime(1289): Shutting down VM
04-19 02:47:05.020: W/dalvikvm(1289): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
04-19 02:47:05.101: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:05.460: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:05.510: E/AndroidRuntime(1289): FATAL EXCEPTION: main
04-19 02:47:05.510: E/AndroidRuntime(1289): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.chriswins2much.Util/com.chriswins2much.Util.LogMeInClientActivity}: android.os.NetworkOnMainThreadException
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.ActivityThread.access$600(ActivityThread.java:123)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.os.Looper.loop(Looper.java:137)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.ActivityThread.main(ActivityThread.java:4424)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at java.lang.reflect.Method.invokeNative(Native Method)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at java.lang.reflect.Method.invoke(Method.java:511)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at dalvik.system.NativeStart.main(Native Method)
04-19 02:47:05.510: E/AndroidRuntime(1289): Caused by: android.os.NetworkOnMainThreadException
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at java.net.InetAddress.getByName(InetAddress.java:295)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at com.chriswins2much.Util.LogMeInClientActivity.onCreate(LogMeInClientActivity.java:37)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.Activity.performCreate(Activity.java:4465)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-19 02:47:05.510: E/AndroidRuntime(1289):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
04-19 02:47:05.510: E/AndroidRuntime(1289):     ... 11 more
04-19 02:47:05.779: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'
04-19 02:47:06.839: I/dalvikvm(1289): threadid=3: reacting to signal 3
04-19 02:47:07.000: I/dalvikvm(1289): Wrote stack traces to '/data/anr/traces.txt'

! Note: Here is a new, new updated code. Force closes are fixed!!! Thank you idiottiger! There is still a problem though. It's not connecting to the port I have set up on localhost:4000 in java. I've tried it non-Android and it works fine. Here is my code to fix the Force close:

public void onCreate(View v){
    // Code...
        new Thread(new Runnable() {
            public void run(){
                try {
                    hostIp = InetAddress.getByName(hostName);
                    localIp = InetAddress.getLocalHost();
                    System.out.println("Local Ip: " + localIp.toString());
                    System.out.println("Host Ip: " + hostIp.toString());
                } catch (UnknownHostException e) {
                    e.printStackTrace();
                }
                try {
                    s = new Socket(hostIp, port);
                    out = new PrintWriter(s.getOutputStream(), true);
                    in = new Scanner(s.getInputStream());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();


}

New logcat below (the latter half of it):

04-19 03:38:02.920: I/System.out(1490): Local Ip: localhost/127.0.0.1
04-19 03:38:03.099: I/System.out(1490): Host Ip: localhost/127.0.0.1
04-19 03:38:05.420: W/System.err(1490): java.net.ConnectException: failed to connect to localhost/127.0.0.1 (port 4000): connect failed: ECONNREFUSED (Connection refused)
04-19 03:38:05.711: W/System.err(1490):     at libcore.io.IoBridge.connect(IoBridge.java:114)
04-19 03:38:05.711: W/System.err(1490):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
04-19 03:38:05.781: W/System.err(1490):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
04-19 03:38:05.781: W/System.err(1490):     at java.net.Socket.startupSocket(Socket.java:566)
04-19 03:38:05.803: W/System.err(1490):     at java.net.Socket.<init>(Socket.java:225)
04-19 03:38:05.809: W/System.err(1490):     at com.chriswins2much.Util.LogMeInClientActivity$1.run(LogMeInClientActivity.java:48)
04-19 03:38:05.839: W/System.err(1490):     at java.lang.Thread.run(Thread.java:856)
04-19 03:38:05.859: W/System.err(1490): Caused by: libcore.io.ErrnoException: connect failed: ECONNREFUSED (Connection refused)
04-19 03:38:05.925: W/System.err(1490):     at libcore.io.Posix.connect(Native Method)
04-19 03:38:05.939: W/System.err(1490):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85)
04-19 03:38:05.979: W/System.err(1490):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
04-19 03:38:05.979: W/System.err(1490):     at libcore.io.IoBridge.connect(IoBridge.java:112)
04-19 03:38:05.989: W/System.err(1490):     ... 6 more
04-19 03:38:06.692: D/gralloc_goldfish(1490): Emulator without GPU emulation detected.

Answer

chriswins2much picture chriswins2much · Apr 21, 2012

OK... Apparently it was the 'localhost' thing. Android runs on another subnet and reserves 127.0.0.1 for itself, so when I tried to connect to the server I set up on localhost:4000, I was calling Android's reserved localhost ip of 127.0.0.1, while the computer's localhost ip was changed to 10.0.2.2 on port 4000.

The fix implemented? It's simple:

I changed this

private final String hostName = "localhost";

to this

private final String hostName = "10.0.2.2";

Or if I had tried it to my ip address (not the localhost one), then it should have worked as well.

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