自己寫的程序崩潰 求大神看看實在不懂那里錯了 ?下面是代碼package com.example.mypptcontrol;import java.io.IOException;import java.io.OutputStream;import java.io.PrintWriter;import java.net.Socket;import java.net.UnknownHostException;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity { private Button loginButton1; private Button loginButton2; private Button loginButton3; private Button loginButton4; private Button loginButton5; public String ppt; PrintWriter pw = null; Socket socket=null; OutputStream os=null; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //初始化連接按鈕 loginButton1 =(Button) findViewById(R.id.button2); loginButton2 =(Button) findViewById(R.id.button5); loginButton3 =(Button) findViewById(R.id.button6); loginButton4 =(Button) findViewById(R.id.button4); loginButton5 =(Button) findViewById(R.id.button1); EditText et = (EditText)findViewById(R.id.editText1); //獲取edittext文本內(nèi)容 String value1 = et.getText().toString(); EditText et2 = (EditText)findViewById(R.id.editText2); loginButton1.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO 自動生成的方法存根 try { socket=new Socket("123.150.226.119",7777); os=socket.getOutputStream(); pw= new PrintWriter(os); } catch (UnknownHostException e) { // TODO 自動生成的 catch 塊 e.printStackTrace(); } catch (IOException e) { // TODO 自動生成的 catch 塊 e.printStackTrace(); } } });? ? ? ? ? ?loginButton2.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO 自動生成的方法存根 ppt="F6"; } }); ? ? ? ? ?loginButton3.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO 自動生成的方法存根 ppt="last"; } }); ? ? ? ? ?loginButton4.setOnClickListener(new OnClickListener() {? ? @Override? public void onClick(View arg0) {? // TODO 自動生成的方法存根? ppt="next";? ? }? });? ? ? ? ?loginButton5.setOnClickListener(new OnClickListener() {? ? @Override? public void onClick(View arg0) {? // TODO 自動生成的方法存根? ppt="stop";? ? }? });? ? ? ? ?if(ppt!="stop"){? ? ? ? ? ? ? ? pw.write(ppt);? ? ? ? pw.flush();? ? ? ? ?? ? ? ? ?}else{? ? ? ? pw.write(ppt);? ? ? ? pw.flush(); try { os.close(); } catch (IOException e) { // TODO 自動生成的 catch 塊 e.printStackTrace(); } try { socket.close(); } catch (IOException e) { // TODO 自動生成的 catch 塊 e.printStackTrace(); }? ? ? ? ?} } public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }這是Logcat報的錯10-27 23:01:36.390: D/AndroidRuntime(1235): Shutting down VM10-27 23:01:36.390: W/dalvikvm(1235): threadid=1: thread exiting with uncaught exception (group=0xb3a0fba8)10-27 23:01:36.400: E/AndroidRuntime(1235): FATAL EXCEPTION: main10-27 23:01:36.400: E/AndroidRuntime(1235): Process: com.example.mypptcontrol, PID: 123510-27 23:01:36.400: E/AndroidRuntime(1235): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mypptcontrol/com.example.mypptcontrol.MainActivity}: java.lang.NullPointerException10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.ActivityThread.access$800(ActivityThread.java:135)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.os.Handler.dispatchMessage(Handler.java:102)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.os.Looper.loop(Looper.java:136)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.ActivityThread.main(ActivityThread.java:5001)10-27 23:01:36.400: E/AndroidRuntime(1235): at java.lang.reflect.Method.invokeNative(Native Method)10-27 23:01:36.400: E/AndroidRuntime(1235): at java.lang.reflect.Method.invoke(Method.java:515)10-27 23:01:36.400: E/AndroidRuntime(1235): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)10-27 23:01:36.400: E/AndroidRuntime(1235): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)10-27 23:01:36.400: E/AndroidRuntime(1235): at dalvik.system.NativeStart.main(Native Method)10-27 23:01:36.400: E/AndroidRuntime(1235): Caused by: java.lang.NullPointerException10-27 23:01:36.400: E/AndroidRuntime(1235): at com.example.mypptcontrol.MainActivity.onCreate(MainActivity.java:102)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.Activity.performCreate(Activity.java:5231)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)10-27 23:01:36.400: E/AndroidRuntime(1235): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)10-27 23:01:36.400: E/AndroidRuntime(1235): ... 11 more10-27 23:01:39.910: I/Process(1235): Sending signal. PID: 1235 SIG: 9求大神看看啊