如何在关闭添加行活动后刷新listview？

Question

该应用程序有两个活动： 首先有+ button和listview。当您点击按钮打开第二个活动时使用edittext和ADDbutton。

当您单击ADDbutton数据写入数据库，然后第二个活动关闭。

那么，如何使第二次活动关闭 - listview在第一次活动刷新？

第一活动：

public class MainScreen extends FragmentActivity implements OnClickListener { 

    final String LOG_TAG = "myLogs"; 
    ListView listViewMain; 
    ImageButton addButton; 
    SQLiteDatabase db; 
    DataBase DB; 
    DBHelper dbHelper; 
    Cursor cursor; 
    SimpleCursorAdapter passListViewAdapter; 


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

     addButton = (ImageButton) findViewById(R.id.addButton); 
     addButton.setOnClickListener(new OnClickListener() { 
      public void onClick(View v) { 
       Log.d(LOG_TAG, "add button : "); 
        Intent intentMain = new Intent(MainScreen.this, AddItem.class); 
        startActivity(intentMain); 
      } 
     }); 

     DB = new DataBase(this); 

     listViewMain = (ListView) findViewById(R.id.listViewMain); 

     String[] from = new String[] { DataBase.COLUMN_TITLE, DataBase.COLUMN_DATE}; 

     int[] to = new int[] { R.id.titleView, R.id.dateView }; 
     if (passListViewAdapter == null) { 
      passListViewAdapter = new SimpleCursorAdapter(
        this, 
        R.layout.item, 
        DB.fetchAllPass(), 
        from, 
        to 
        , SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER); 
     } else { 
      passListViewAdapter.notifyDataSetChanged();    
     } 

     listViewMain.setAdapter(passListViewAdapter); 


} 

@Override 
protected void onPause() { 
    super.onPause(); 
} 

@Override 
protected void onResume() { 
    super.onResume(); 
} 

第二活动（行项相加）：

public class AddItem extends MainScreen implements OnClickListener{ 
    final String LOG_TAG = "myLogs"; 
    EditText comment_enter, link_enter, password_enter, login_enter, title_enter, date_enter; 
    Button add_item_button; 
    DBHelper db; 
    DataBase DB; 
    SimpleCursorAdapter passListViewAdapter; 
    SimpleDateFormat sdf; 
    private Cursor cursor = null; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.add_item); 
    comment_enter = (EditText) findViewById(R.id.comment_enter); 
    link_enter = (EditText) findViewById(R.id.link_enter); 
    password_enter = (EditText) findViewById(R.id.password_enter); 
    login_enter = (EditText) findViewById(R.id.login_enter); 
    title_enter = (EditText) findViewById(R.id.title_enter); 
    date_enter = (EditText) findViewById(R.id.date_enter); 
    SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy"); 
    String date = sdf.format(new Date(System.currentTimeMillis())); 
    date_enter.setText(date); 

    add_item_button = (Button) findViewById(R.id.add_item_button); 
    add_item_button.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      Log.d(LOG_TAG, "add_item_button : "); 
      String title_str = title_enter.getText().toString(); 
      String login_str = login_enter.getText().toString(); 
      String pass_str = password_enter.getText().toString(); 
      String link_str = link_enter.getText().toString(); 
      String comm_str = comment_enter.getText().toString(); 

      String date_str = date_enter.getText().toString(); 

      Log.d(LOG_TAG, "Strings: " + title_str + " " + login_str + " " + pass_str + " " + link_str + " " + comm_str + " " + date_str); 
      DataBase DB = new DataBase(AddItem.this); 
      DB.open(); 
      DB.insertPass(title_str, login_str, pass_str, link_str, comm_str, date_str); 
      DB.close(); 
      Log.d(LOG_TAG, "after inserting into DB : "); 
      finish(); 
     } 
    }); 
} 

@Override 
protected void onPause() { 
    super.onPause(); 
    finish(); 
    Log.d(LOG_TAG, "onPause : "); 
} 
} 

数据库活动：

public long insertPass (String tt, String lg, String ps, String ul, 
    String cm, String dt) { 
openGuard(); 
ContentValues cv = new ContentValues(); 
cv.put(COLUMN_TITLE, tt); 
cv.put(COLUMN_LOGIN, lg); 
cv.put(COLUMN_PASSWORD, ps); 
cv.put(COLUMN_URL, ul); 
cv.put(COLUMN_COMMENT, cm); 
cv.put(COLUMN_DATE, dt); 

return db.insert(TABLE_NAME, null, cv);} 

public Cursor fetchAllPass() throws SQLException { 
openGuard(); 
return db.query(TABLE_NAME, new String[] {COLUMN_ID, COLUMN_TITLE, COLUMN_DATE}, null, null, null, null, null);} 

logcat的

02-12 17:24:44.626: D/AndroidRuntime(21123): Shutting down VM 
02-12 17:24:44.626: W/dalvikvm(21123): threadid=1: thread exiting with uncaught exception (group=0x415e3c80) 
02-12 17:24:44.626: E/AndroidRuntime(21123): FATAL EXCEPTION: main 
02-12 17:24:44.626: E/AndroidRuntime(21123): Process: com.ssd.passwordmanager, PID: 21123 
02-12 17:24:44.626: E/AndroidRuntime(21123): java.lang.RuntimeException: Unable to resume activity {com.ssd.passwordmanager/com.ssd.passwordmanager.AddItem}: java.lang.NullPointerException 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2808) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2837) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2270) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.ActivityThread.access$800(ActivityThread.java:145) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1206) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.os.Handler.dispatchMessage(Handler.java:102) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.os.Looper.loop(Looper.java:136) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.ActivityThread.main(ActivityThread.java:5081) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at java.lang.reflect.Method.invokeNative(Native Method) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at java.lang.reflect.Method.invoke(Method.java:515) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:781) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at dalvik.system.NativeStart.main(Native Method) 
02-12 17:24:44.626: E/AndroidRuntime(21123): Caused by: java.lang.NullPointerException 
02-12 17:24:44.626: E/AndroidRuntime(21123): at com.ssd.passwordmanager.MainScreen.onResume(MainScreen.java:111) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1192) 
02-12 17:24:44.626: E/AndroidRuntime(21123): at android.app.Activity.performResume(Activity.java:5310) 

Answer 1

最简单的方法是将您的加载代码部分添加到第一个活动的onResume中。这样，每次显示活动时它都会刷新。