Question

我的数据库中有一个名为Meal的下表。我想将MealType列加载到数组中，以便我可以使用值填充ListView。

这是我的数据库表：这是我的DataAccess类：

public class DataAccess {

String ip = "sict-sql.n***.ac.za";
String classs = "net.sourceforge.jtds.jdbc.Driver";
String db = "eMenu";
String un = "cyber";
String password = "********";


public DataAccess(String Ip, String Classs, String Db, String Un, String Password) {
    ip = Ip;
    classs = Classs;
    db = Db;
    un = Un;
    password = Password;
}

public String getip() {
    return ip;

}

public String getclasss() {return classs;}

public String getdb() {return db;}

public String getun() {return un;}

public String getpassword() {return password;}

public void setip(String Ip) {ip = Ip;}

public void setdb(String Db) {db = Db;}

public void setclasss(String Classs) {classs = Classs;}

public void setun(String Un) {un = Un;}

public void setpassword(String Password) {password = Password;}



}

这是我的MainActivity：

public class MainActivity extends ActionBarActivity {

 public String[] categories;
 public ListView lstCategories;
 public String[] categories = {"A"};
 DataAccess connectionClass;
String datets;
String call, db, un, passwords;
Connection connect;
ResultSet rs;



@Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.homescreen);

    connectionClass = new DataAccess();
    call = connectionClass.getip();
    un = connectionClass.getun();
    passwords = connectionClass.getpassword();
    db = connectionClass.getdb();
    connect = conn(un, passwords, db, call);
    GetListViewValue(connect);

}

@SuppressLint("NewApi")
    public Connection conn(String _user, String _pass, String _DB,String _server) {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);
        Connection conn = null;
        String ConnURL = null;

    try {
        Class.forName("net.sourceforge.jtds.jdbc.Driver");
        ConnURL = "jdbc:sqlserver://" + _server + ";"+ "databaseName=" + _DB + "integratedSecurity=true;;user=" + _user + ";password=" + _pass ;
        conn = DriverManager.getConnection(ConnURL);
    } catch (SQLException se) {
        Toast.makeText(MainActivity.this, "ERROR: " + se.getMessage(), Toast.LENGTH_LONG).show();
    } catch (ClassNotFoundException e) {
        Toast.makeText(MainActivity.this, "ERROR: " + e.getMessage(), Toast.LENGTH_LONG).show();
    } catch (Exception e) {
        Toast.makeText(MainActivity.this, "ERROR: " + e.getMessage(), Toast.LENGTH_LONG).show();
    }
    return conn;
}

public void GetListViewValue(Connection connect){
    String querycmd = "SELECT * FROM Meal;";
    Statement state = null;
    try {

            state = connect.createStatement();
            rs = state.executeQuery(querycmd);


            List<Map<String, String>> data = null;

            data = new ArrayList<Map<String, String>>();
            while (rs.next()) {
                Map<String, String> datanum = new HashMap<String, String>();
                datanum.put("A", rs.getString("MealType"));
                data.add(datanum);

                lstCategories = (ListView) findViewById(R.id.lvCategories);
                Typeface font = Typeface.createFromAsset(getAssets(), "Abel-Regular.ttf");


                lstCategories.setOnItemClickListener(
                        new AdapterView.OnItemClickListener() {
                            @Override
                            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                                value = (String) lstCategories.getItemAtPosition(position);

                                Toast.makeText(MainActivity.this, value + "? Good choice", Toast.LENGTH_LONG).show();
                                switch (value) {

                                    default:
                                        Intent to = new Intent(MainActivity.this, MenuActivity.class);

                                        startActivity(to);

                                        break;
                                }

                            }

                        }

                );


            }

    } catch (SQLException e) {
        Toast.makeText(MainActivity.this, e.getMessage().toString(), Toast.LENGTH_LONG).show();

    }
    finally {
        if (rs != null) try { rs.close(); } catch(Exception e) {}
        if (state != null) try { state.close(); } catch(Exception e) {}
        if (connect != null) try { connect.close(); } catch(Exception e) {}
    }

}


 }

这是我的homescreen.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="1"
android:id="@+id/loMain">

<LinearLayout
        android:orientation="horizontal"
        android:layout_width="350dp"
        android:layout_height="match_parent"
        android:weightSum="1">

        <ListView
            android:layout_width="350dp"
            android:layout_height="wrap_content"
            android:id="@+id/lvCategories" />



    </LinearLayout>
</LinearLayout>

Toast给我一个net.sourceforge.jtds.jdbc.Driver错误，然后应用程序关闭。这是logcat：

07-09 05:53:43.684 2248-2248/siphe.androidapp E/AndroidRuntime: FATAL EXCEPTION: main
  Process: siphe.androidapp, PID: 2248
  java.lang.RuntimeException: Unable to start activity ComponentInfo{siphe.androidapp/siphe.androidapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.Statement java.sql.Connection.createStatement()' on a null object reference
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
      at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3947)
      at android.app.ActivityThread.access$900(ActivityThread.java:151)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1309)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:135)
      at android.app.ActivityThread.main(ActivityThread.java:5254)
      at java.lang.reflect.Method.invoke(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:372)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
   Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.Statement java.sql.Connection.createStatement()' on a null object reference
      at siphe.androidapp.MainActivity$override.GetListViewValue(MainActivity.java:87)
      at siphe.androidapp.MainActivity$override.access$dispatch(MainActivity.java)
      at siphe.androidapp.MainActivity.GetListViewValue(MainActivity.java:0)
      at siphe.androidapp.MainActivity$override.onCreate(MainActivity.java:57)
      at siphe.androidapp.MainActivity$override.access$dispatch(MainActivity.java)
      at siphe.androidapp.MainActivity.onCreate(MainActivity.java:0)
      at android.app.Activity.performCreate(Activity.java:5990)
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
      at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3947) 
      at android.app.ActivityThread.access$900(ActivityThread.java:151) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1309) 
      at android.os.Handler.dispatchMessage(Handler.java:102) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5254) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

我认为这是我安装的驱动程序。请帮忙

我的jdts驱动程序给我的android studio sql server连接错误

0 个答案: