Java 在SQLite数据库中保存SSID数据会导致强制关闭

我正在尝试使用其他数据（用户当前的SSID）更新数据库，但是在尝试保存数据库时，整个应用程序强制关闭

我知道在保存数据时会出现NullPointer异常，但我不知道是什么原因造成的

日志：

04-04 21:24:08.351: E/AndroidRuntime(10745): FATAL EXCEPTION: AsyncTask #2
04-04 21:24:08.351: E/AndroidRuntime(10745): java.lang.RuntimeException: An error occured while executing doInBackground()
04-04 21:24:08.351: E/AndroidRuntime(10745):    at android.os.AsyncTask$3.done(AsyncTask.java:299)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.util.concurrent.FutureTask.run(FutureTask.java:239)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.lang.Thread.run(Thread.java:856)
04-04 21:24:08.351: E/AndroidRuntime(10745): Caused by: java.lang.NullPointerException
04-04 21:24:08.351: E/AndroidRuntime(10745):    at com.app.gamedemo.AddEditDevice.saveContact(AddEditDevice.java:117)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at com.app.gamedemo.AddEditDevice.access$1(AddEditDevice.java:111)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at com.app.gamedemo.AddEditDevice$1$1.doInBackground(AddEditDevice.java:83)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at android.os.AsyncTask$2.call(AsyncTask.java:287)
04-04 21:24:08.351: E/AndroidRuntime(10745):    at java.util.concurrent.FutureTask.run(FutureTask.java:234)
04-04 21:24:08.351: E/AndroidRuntime(10745):    ... 4 more

资料来源：（更新了w SCF的建议）

ADDEDITDEVICE.java

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.ViewGroup;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.TimePicker;
import java.text.DecimalFormat;


public class AddEditDevice extends Activity {

     private long rowID; 
     private EditText nameEt;
     private EditText capEt;
     private EditText codeEt;
     private TimePicker timeEt;
     private TextView ssidTextView;


      // @Override
       public void onCreate(Bundle savedInstanceState) 
       {
          super.onCreate(savedInstanceState); 
          setContentView(R.layout.add_country);
          WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
          WifiInfo info = wifi.getConnectionInfo();
          String ssidString = info.getSSID();

          //TextView ssidTextView = (TextView) findViewById(R.id.wifiSSID);
          ssidTextView = (TextView) findViewById(R.id.wifiSSID);
          ssidTextView.setText(ssidString); 

          nameEt = (EditText) findViewById(R.id.nameEdit);
          capEt = (EditText) findViewById(R.id.capEdit);
          codeEt = (EditText) findViewById(R.id.codeEdit);
          timeEt = (TimePicker) findViewById(R.id.timeEdit);






          Bundle extras = getIntent().getExtras(); 

          if (extras != null)
          {
             rowID = extras.getLong("row_id");
             nameEt.setText(extras.getString("name"));  
             capEt.setText(extras.getString("cap"));  
             codeEt.setText(extras.getString("code"));    
             String time = extras.getString("time");
             String[] parts = time.split(":");
             timeEt.setCurrentHour(Integer.valueOf(parts[0]));
             timeEt.setCurrentMinute(Integer.valueOf(parts[1]));
             timeEt.setIs24HourView(false);


          }

          Button saveButton =(Button) findViewById(R.id.saveBtn);
          saveButton.setOnClickListener(new OnClickListener() {

              public void onClick(View v) 
              {
                 if (capEt.getText().length() != 0)
                 {
                    AsyncTask<Object, Object, Object> saveContactTask = 
                       new AsyncTask<Object, Object, Object>() 
                       {
                          @Override
                          protected Object doInBackground(Object... params) 
                          {
                             saveContact();
                             return null;
                          }

                          @Override
                          protected void onPostExecute(Object result) 
                          {
                             finish();
                          }
                       }; 

                    saveContactTask.execute((Object[]) null); 
                 }

                 else
                 {
                    AlertDialog.Builder alert = new AlertDialog.Builder(AddEditDevice.this);
                    alert.setTitle(R.string.errorTitle); 
                    alert.setMessage(R.string.errorMessage);
                    alert.setPositiveButton(R.string.errorButton, null); 
                    alert.show();
                 }
              } 
         });}




           private void saveContact() 
           {
              DatabaseConnector dbConnector = new DatabaseConnector(this);

              if (getIntent().getExtras() == null)
              {
                  dbConnector.insertContact(nameEt.getText().toString(),
                          capEt.getText().toString(),
                          timeEt.getCurrentHour().toString() + ":"
                              + timeEt.getCurrentMinute().toString(),
                          codeEt.getText().toString(),
                       ssidTextView.getText().toString());

              }
              else
              {
                 dbConnector.updateContact(rowID,
                         nameEt.getText().toString(),
                            capEt.getText().toString(),
                              timeEt.getCurrentHour().toString() + ":"
                                  + timeEt.getCurrentMinute().toString(),
                              codeEt.getText().toString(),
                              ssidTextView.getText().toString());
              }
           }
}

---

我认为您的问题在于将TextView保存到局部变量“ssidTextView”中，而应该将其保存到字段“ssid”中。 换衣服

TextView ssidTextView = (TextView) findViewById(R.id.wifiSSID);

进入

---

当然，您还必须将“String ssid”重命名为其他名称，例如“ssidString”。

在尝试将数据存储到数据库之前，会引发NullPointerException。您需要检查AddEditDevice.java:117中可能为null的内容，并可能将变量和调用分离（用于调试），这是在添加以下行时引起的：ssid.getText（）.toString（））；但我不确定如何纠正这个问题。我按照您的建议更新了源代码，但现在我遇到了两个新错误：ssidString无法解析为变量，ssidTextView无法解析为“ssidString”前面的“String”。您最初的问题是，您给了两个不同的变量相同的名称“ssid”。以后不要这样做，你会省去很多麻烦。太棒了！谢谢（这解决了1/2的问题-但我仍然得到“ssidTextView无法解决”错误）就在您声明的“private TextView ssid；”的“onCreate”上方。如果要通过“ssidTextView”调用TextView，则应相应更改此声明。

TextView ssidTextView = (TextView) findViewById(R.id.wifiSSID);

ssid = (TextView) findViewById(R.id.wifiSSID);