试图调用虚拟方法'android.text.Editable android.widget.EditText.getText（）'null对象引用

Question

我试图保存输入到我的数据库的数据，但是，我得到以下错误：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference 
                        at ie.example.artur.adminapp.MainActivity$Send.<init>(MainActivity.java:62) 

我看了其他类似的问题，并比较了我的问题，并没有发现相同的问题。如果这是一个太简单的问题，但我并不经常使用java。

This is my MainActivity : 



package ie.example.artur.adminapp; 

import android.os.AsyncTask; 
import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.Statement; 

public class MainActivity extends AppCompatActivity { 


    EditText editText; 
    TextView textView; 
    private static final String DB_URL = "jdbc:mysql://192.168.1.6/tutorial"; 
    private static final String USER = "zzz"; 
    private static final String PASS = "zzz"; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     textView = (TextView) findViewById(R.id.textView); 
     editText = (EditText) findViewById(R.id.editText); 

     setContentView(R.layout.activity_register); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
         .setAction("Action", null).show(); 
      } 
     }); 
    } 

    public void btnConn(View view) { 
     Send objSend = new Send(); 
     objSend.execute(""); 


    } 

    private class Send extends AsyncTask<String, String, String> 

    { 
     String msg = ""; 
     String text = editText.getText().toString(); 


     @Override 
     protected void onPreExecute() { 
      textView.setText("Please Wait Inserting Data"); 
     } 

     @Override 
     protected String doInBackground(String... strings) { 
      try { 
       Class.forName("com.mysql.jdbc.Driver"); 
       Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); 
       if (conn == null) { 
        msg = "Connection goes wrong"; 
       } else { 
        String query = "Insert INTO student (name) VALUES('" + text + "')"; 
        Statement stmt = conn.createStatement(); 
        stmt.executeUpdate(query); 
        msg = "Inserting Successful!!"; 
       } 

       conn.close(); 

     } 

     catch(
     Exception e 
     ) 

     { 
      msg = "Connection goes Wrong"; 
      e.printStackTrace(); 

     } 

     return msg; 


    } 



@Override 
    protected void onPostExecute(String msg) {textView.setText(msg);} 



    } 




} 

这是我activity_register.xml：

<android.support.design.widget.AppBarLayout 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:theme="@style/AppTheme.AppBarOverlay"> 

     <android.support.v7.widget.Toolbar 
      android:id="@+id/toolbar" 
      android:layout_width="match_parent" 
      android:layout_height="?attr/actionBarSize" 
      android:background="?attr/colorPrimary" 
      app:popupTheme="@style/AppTheme.PopupOverlay" /> 

    </android.support.design.widget.AppBarLayout> 

    <include layout="@layout/content_main" /> 

    <android.support.design.widget.FloatingActionButton 
     android:id="@+id/fab" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="bottom|end" 
     android:layout_margin="@dimen/fab_margin" 
     android:src="@android:drawable/ic_dialog_email" /> 

</android.support.design.widget.CoordinatorLayout> 

Answer 1

移动你的setContentView到活动开始

super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_register 

textView = (TextView) findViewById(R.id.textView); 
editText = (EditText) findViewById(R.id.editText);