应用程序强制在启动时关闭答案

【问题标题】：Application Force Closes On Startup应用程序强制在启动时关闭
【发布时间】：2012-04-30 13:03:43
【问题描述】：

好吧，我正在尝试制作一个与我已经设置、测试并在一个简单的 java 应用程序后台运行的套接字通信的应用程序。

问题是，我的应用程序会立即强制关闭。在 fcs 之前你没有机会看到任何东西。

这是我的代码：

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;
            }
        }
    }
}

在上面的代码中，“A”或“B”都不会打印出来。该应用程序只是 fc 的。

这是我的清单：

<?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>

我使用了上述权限，因为我听说它会有所帮助。

我更新了代码以修复 EditText NullPointerException 修复（仅更改部分）：

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();
        }
    }

下面是新的logcat：

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'

！注意：这是一个新的、新的更新代码。强制关闭已修复！！！谢谢白痴！不过还是有问题。它没有连接到我在 java 中在 localhost:4000 上设置的端口。我已经尝试过非Android，它工作正常。这是我修复强制关闭的代码：

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();


}

新logcat如下（后半部分）：

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.

【问题讨论】：

此行导致错误：passwordField = (EditText) findViewById(R.id.password_field);了解如何阅读堆栈跟踪，它会告诉你这一点（即“Caused by:”）
它仍然无法正常工作，但是，是的，我以前没有看到。提前感谢未来的问题，它可能会救我。
正在使用平板电脑应用程序 NetworkOnMainThread 将发生异常。尝试从另一个非 ui 线程区域调用。尝试访问 stackoverflow.com/questions/6343166/… 并在代码中添加严格模式。
对于严格模式，请阅读此developer.android.com/reference/android/os/…。当您必须通过 ui 线程启动线程时，此模式很有用。
喜欢这个？ StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().permitAll().build());

标签： android sockets android-activity forceclose

【解决方案1】：

好的...显然这是“本地主机”的事情。 Android 运行在另一个子网上并为自己保留 127.0.0.1，所以当我尝试连接到我在 localhost:4000 上设置的服务器时，我调用的是 Android 保留的 localhost ip 127.0.0.1，而计算机的 localhost ip 更改为10.0.2.2 在 4000 端口上。

修复已实施？很简单：

我改变了这个

private final String hostName = "localhost";

到这里

private final String hostName = "10.0.2.2";

或者，如果我尝试使用我的 IP 地址（不是本地主机），那么它应该也可以工作。

【讨论】：

【解决方案2】：

我认为您正在使用与互联网相关的东西。我没有在你的清单文件中看到许可。

<uses-permission android:name="android.permissions.INTERNET" />

【讨论】：

我将它添加到清单中，但它仍然给了我同样的 logcat 东西。我的意思完全一样。
我认为是第 37 行的事情，但我不确定
抱歉。它的权限不是权限
hostIp = InetAddress.getByName(hostName);其中主机名 = “本地主机”？
你是从这里粘贴的吗？如果是这样，请将其更改为许可。没有权限

【解决方案3】：

这些代码可能有问题：

 private final EditText usernameField = (EditText) findViewById(R.id.username_field),
            passwordField = (EditText) findViewById(R.id.password_field);

视图需要在setContentView之后初始化，所以改成这样：

private EditText usernameField,passwordField;

在setContentView之后添加关注代码：

usernameField = (EditText) findViewById(R.id.username_field),
passwordField = (EditText) findViewById(R.id.password_field);

如果它不能解决您的问题，您需要检查视图 ID：R.id.username_field 和 R.id.password_field 是否存在于您的 main.xml 文件中。

更新：

你的新错误：NetworkOnMainThreadException

这仅适用于面向 Honeycomb SDK 或更高版本的应用程序。允许以早期 SDK 版本为目标的应用程序在其主事件循环线程上进行网络连接，但非常不鼓励这样做。请参阅文档响应性设计。

它喜欢你InetAddress.getByName需要阻止main thread，所以尝试在另一个线程中使用，或者将sdk目标版本更改为低如：

另外，您需要在 xml 中添加网络权限：

<uses-permission android:name="android.permission.INTERNET" />

【讨论】：

你能用新代码更新并粘贴新的错误信息吗？
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. 你是怎么测试的？问题是：你的安卓设备中有没有4000端口的服务器？ SocketSever 启动了吗？如果不是套接字，则需要使用 urlconnection 进行连接。
我在 Java 的 4000 端口上设置了一个 ServerSocket，它与模拟器设置在同一台计算机上。现在，它只是创建了一个新的自定义线程来读取输入并回显它。我在另一个 java 程序中设置了一个 Socket，在 localhost 端口 4000 上设置，该程序使用 Scanner(System.In) 对象从键盘获取输入并发送它。我在 Eclipse 的控制台中同时使用它们。它们可以很好地相互发送和回显。

【解决方案4】：

你的问题是 AndroidManifest.xml

如果您将
uses-sdk android:minSdkVersion="15" 更改为 uses-sdk android:minSdkVersion="8" 程序没问题。

我不知道怎么办

【讨论】：