Android的MySQL與Java代碼沒有響應

Question

我已經在我的computer.and安裝了mysql，並且還有碼頭..我的要求： - 我有一個數據庫學生與表名稱ari; ARI表是： -

+----+-------+ 
| id | name | 
+----+-------+ 
| 22 | Sandy | 
+----+-------+ 

從我的Android程序中，我想從database..I獲取它已經這樣做了： - MainActivity3.java

public class MainActivity3 extends Activity { 
    private static final String url = "jdbc:mysql://localhost:3306/student"; 
    private static final String user = "root"; 
    private static final String pass = "root"; 
    TextView tv; 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     tv = (TextView)findViewById(R.id.textView1); 
     Connect(); 
    } 

private class Connect extends AsyncTask<String, Void, String> { 
       @Override 
       protected String doInBackground(String... urls) { 
        String response = ""; 
     try { 
      Class.forName("com.mysql.jdbc.Driver"); 
      Connection con = DriverManager.getConnection(url, user, pass); 
      String result = "Database connection success\n"; 
      Statement st = con.createStatement(); 
      ResultSet rs = st.executeQuery("select * from ari"); 
      ResultSetMetaData rsmd = rs.getMetaData(); 
      while(rs.next()) { 
       result += rsmd.getColumnName(1) + ": " + rs.getInt(1) + "\n"; 
       result += rsmd.getColumnName(2) + ": " + rs.getString(2) + "\n"; 
         } 
      tv.setText(result); 
     } 
     catch(Exception e) { 
      e.printStackTrace(); 
      tv.setText(e.toString()); 
     } 
     return response; 
     } 

     @Override 
     protected void onPostExecute(String result) { 
      tv.setText(result); 
     } 
     } 
     public void Connect() { 
     Connect task = new Connect(); 
      task.execute(); 
     } 
    } 

但其顯示的錯誤： - -

FATAL EXCEPTION: AsyncTask #1 
Process: com.TourBus.info, PID:2 
java.lang.RuntimeException: An error occured while executing doInBackground() 
    at android.os.AsyncTask$3.done(AsyncTask.java:300) 
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) 
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222) 
    at java.util.concurrent.FutureTask.run(FutureTask.java:242) 
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
    at java.lang.Thread.run(Thread.java:841) 
Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 
    at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6661) 
    at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:969) 
at android.view.View.requestLayout(View.java:16767) 
    at android.view.View.requestLayout(View.java:16767) 
    at android.view.View.requestLayout(View.java:16767) 
    at android.view.View.requestLayout(View.java:16767) 
    at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:369) 
    at android.view.View.requestLayout(View.java:16767) 
    at android.widget.TextView.checkForRelayout(TextView.java:6820) 
    at android.widget.TextView.setText(TextView.java:3889) 
    at android.widget.TextView.setText(TextView.java:3728) 
    at android.widget.TextView.setText(TextView.java:3703) 
    at com.TourBus.info.MainActivity3$Connect.doInBackground(MainActivity3.java:46) 
    at com.TourBus.info.MainActivity3$Connect.doInBackground(MainActivity3.java:1) 
    at android.os.AsyncTask$2.call(AsyncTask.java:288) 

我有mysql connector.jar但仍然存在問題？

Answer 1

我不相信你可以更新AsyncTask裏面的視圖。嘗試這個。

runOnUiThread(new Runnable() { 
@Override 
public void run() { 
    // setText() here 
} 
});