我在我的电脑上运行了一个简单的套接字服务器，我为个人电脑提供了一个客户端，但是我想让它适应Android，但它一直在崩溃，告诉我在closeChat（）方法中出现了问题但是我无法弄清楚是什么。这是我的代码：
package com.jister13.chattest;
import java.io.EOFException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.InetAddress;
import java.net.Socket;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class ChatRoom extends Activity
{
String ip;
EditText userText;
EditText chatWindow;
Button send;
private ObjectOutputStream output;
private ObjectInputStream input;
private String message = "";
private String serverIP;
private Socket connection;
private Handler handler;
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Bundle extras = getIntent().getExtras();
if(extras != null)
{
ip = extras.getString("IP");
serverIP = ip;
}
setContentView(R.layout.chat_room);
setRequestedOrientation(1);
handler = new Handler();
userText = (EditText) findViewById(R.id.editText_UserText);
chatWindow = (EditText) findViewById(R.id.editText_ChatWindow);
chatWindow.addTextChangedListener(new TextWatcher(){
public void afterTextChanged(Editable s) {
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before, int count) {
Toast.makeText(ChatRoom.this, "Updated", Toast.LENGTH_LONG).show();
}
});
send = (Button) findViewById(R.id.button_Send);
send.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
sendMessage("You: " + userText.getText().toString() + "\n");
userText.setText("");
}
});
startRunning();
}
public void startRunning()
{
try{
connectToServer();
setupStreams();
whileChatting();
}catch(EOFException eofException){
showMessage("\n Chat Session Closed");
}catch(IOException ioException){
ioException.printStackTrace();
}finally{
closeChat();
}
}
private void connectToServer() throws IOException
{
showMessage("Starting Connection...");
connection = new Socket(InetAddress.getByName(serverIP), 0511);
showMessage("\n Connection Established: "+connection.getInetAddress().getHostName());
}
private void setupStreams() throws IOException
{
output = new ObjectOutputStream(connection.getOutputStream());
output.flush();
input = new ObjectInputStream(connection.getInputStream());
showMessage("\n Chatting streams are now enabled...");
}
private void whileChatting() throws IOException
{
ableToType(true);
do{
try{
message = (String) input.readObject();
showMessage("\n "+message);
}catch(ClassNotFoundException classNotFoundException){
showMessage("\n Some Error Occured");
}
}while(!message.equals("SERVER - END"));
}
private void closeChat()
{
showMessage("\n Closing Application...");
ableToType(false);
try{
input.close();
output.close();
connection.close();
}catch(IOException e){
e.printStackTrace();
}
}
private void sendMessage(String text)
{
try{
output.writeObject("Else: "+text);
output.flush();
showMessage("You: "+text+"\n");
}catch(IOException e){
chatWindow.append("\n An Error Occured *See ChatRoom.java -> sendMessage()*");
}
}
private void showMessage(final String message)
{
handler.post(new Runnable(){
public void run(){
chatWindow.append(message);
}
});
}
private void ableToType(final boolean TorF)
{
//userText.setEditable(TorF);
}
}
http://www.mediafire.com/view/?hr441qalu6b6d7s这是错误缩小的图像。
继承整个PrintStackTrace：
03-08 11:02:43.595: E/AndroidRuntime(3959): FATAL EXCEPTION: main
03-08 11:02:43.595: E/AndroidRuntime(3959): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jister13.chattest/com.jister13.chattest.ChatRoom}: java.lang.NullPointerException
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2088)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2113)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.ActivityThread.access$700(ActivityThread.java:139)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1224)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.os.Looper.loop(Looper.java:137)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.ActivityThread.main(ActivityThread.java:4918)
03-08 11:02:43.595: E/AndroidRuntime(3959): at java.lang.reflect.Method.invokeNative(Native Method)
03-08 11:02:43.595: E/AndroidRuntime(3959): at java.lang.reflect.Method.invoke(Method.java:511)
03-08 11:02:43.595: E/AndroidRuntime(3959): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1004)
03-08 11:02:43.595: E/AndroidRuntime(3959): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:771)
03-08 11:02:43.595: E/AndroidRuntime(3959): at dalvik.system.NativeStart.main(Native Method)
03-08 11:02:43.595: E/AndroidRuntime(3959): Caused by: java.lang.NullPointerException
03-08 11:02:43.595: E/AndroidRuntime(3959): at com.jister13.chattest.ChatRoom.closeChat(ChatRoom.java:115)
03-08 11:02:43.595: E/AndroidRuntime(3959): at com.jister13.chattest.ChatRoom.startRunning(ChatRoom.java:82)
03-08 11:02:43.595: E/AndroidRuntime(3959): at com.jister13.chattest.ChatRoom.onCreate(ChatRoom.java:69)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.Activity.performCreate(Activity.java:5048)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
03-08 11:02:43.595: E/AndroidRuntime(3959): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2052)
03-08 11:02:43.595: E/AndroidRuntime(3959): ... 11 more
答案 0 :(得分：0)
简单地说，input为空。
运行时：
public void startRunning()
{
try{
connectToServer();
setupStreams();
whileChatting();
}catch(EOFException eofException){
showMessage("\n Chat Session Closed");
}catch(IOException ioException){
ioException.printStackTrace();
}finally{
closeChat();
}
}
private void connectToServer() throws IOException
{
showMessage("Starting Connection...");
connection = new Socket(InetAddress.getByName(serverIP), 0511);
showMessage("\n Connection Established: "+connection.getInetAddress().getHostName());
}
private void setupStreams() throws IOException
{
output = new ObjectOutputStream(connection.getOutputStream());
output.flush();
input = new ObjectInputStream(connection.getInputStream());
showMessage("\n Chatting streams are now enabled...");
}
如果您在input中分配setupStreams()之前的任何地方收到例外，那么当finally拨打closeChat()时，它将为空。由于你没有在那里检查null，它会翻转。
我的建议？在使用它们之前先检查一下：
private void closeChat()
{
...
if(input != null)
input.close();
if(output != null)
output.close();
if(connection != null)
connection.close();
....
}