直到应用程序被销毁并重新启动（sqlite 游标），文本才会更新

Question

我正在开发一个 android 应用程序，该应用程序使用 sqlite 数据库来包含用户输入的信息。我有两个活动。当前主要 activity 显示来自数据库的用户信息。第二个 activity 仅用于输入该数据。当第二个 activity 打开时，我在编辑文本框中看到保存的数据。我可以修改和保存数据。但是，当返回到第一个 activity 时，那里显示的数据不会更新。如果我关闭应用程序并重新启动它，新数据将正确显示在第一个 activity 中，但我需要它立即显示。我已经尝试覆盖 onResume() 认为这会有所帮助。但到目前为止它对我没有帮助。请帮我找出问题所在。这是我的主要 activity，第一个 activity:

public class LaunchActivity extends AppCompatActivity{

final String SCOPE ="https://www.googleapis.com/auth/gmail.send";

private static final int REQUEST_RESOLVE_AUTH_ERROR = 1006;
private static final int REQUEST_SMS = 645;
private ImageView mImageView;
private TextView nameField;
private TextView phoneField;
private TextView emailField;
private ClientInfoDBHelper mInfoDBHelper;
private Cursor mCursor;

private String mPhoneNumber = "**********";
private String[] permissions = new String[]{Manifest.permission.SEND_SMS, Manifest.permission.READ_PHONE_STATE};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_launch);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    nameField = (TextView) findViewById(R.id.nameView);
    phoneField = (TextView) findViewById(R.id.phoneView);
    emailField = (TextView) findViewById(R.id.emailView);

    mInfoDBHelper = new ClientInfoDBHelper(this);
    SQLiteDatabase dbReader = mInfoDBHelper.getReadableDatabase();
    String[] projection = {
            ClientInfoContract.ClientInfoEntry.FIRST_NAME,
            ClientInfoContract.ClientInfoEntry.LAST_NAME,
            ClientInfoContract.ClientInfoEntry.PHONE_NUMBER,
            ClientInfoContract.ClientInfoEntry.EMAIL_ADDRESS
    };

    String where = ClientInfoContract.ClientInfoEntry._ID + " = ?";
    String[] whereArgs = {"1"};
    String sortOrder = ClientInfoContract.ClientInfoEntry.FIRST_NAME + " DESC";

    mCursor = dbReader.query(
            ClientInfoContract.ClientInfoEntry.TABLE_NAME,
            projection,
            where,
            whereArgs,
            null,
            null,
            sortOrder
    );
    mCursor.moveToNext();
    updateDisplayInfo(mCursor);

    //request permissions
    int MyVersion = Build.VERSION.SDK_INT;
    if (MyVersion> Build.VERSION_CODES.LOLLIPOP_MR1){
        if (hasPermission()){
            ActivityCompat.requestPermissions(this, permissions, REQUEST_SMS);
        }
    }

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Are you certain you'd like to alert your attorney?", Snackbar.LENGTH_INDEFINITE)
                    .setAction(R.string.snack_bar_send, new View.OnClickListener(){
                        @Override
                        public void onClick(View v){
                            SmsManager smsManager = SmsManager.getDefault();
                            smsManager.sendTextMessage(mPhoneNumber, null, "testing", null, null);
                            new MailTask().execute();
                        }
                    }).show();
        }
    });

    mImageView = (ImageView) findViewById(R.id.imageView);
    mImageView.setImageDrawable(getResources().getDrawable(R.drawable.no_handcuffs));

}

@Override
public void onResume(){
    super.onResume();;
    updateDisplayInfo(mCursor);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_launch, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
   switch (id){
       case R.id.action_settings:
           //null
           break;
       case R.id.userInfo:
           Intent infoIntent = new Intent(this, UserInfoActivity.class);
           startActivity(infoIntent);
           break;
   }

    return super.onOptionsItemSelected(item);
}

private boolean hasPermission(){
    int result = ContextCompat.checkSelfPermission(this, permissions[0]);
    if (result==PackageManager.PERMISSION_DENIED){
        return true;
    }else {
        return false;
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults){
    //temporarily null// may be used in future to handle multiple permissions
}


public void updateDisplayInfo(Cursor curse){
    //curse.moveToNext();
    StringBuilder sb = new StringBuilder();
    sb.append(curse.getString(curse.getColumnIndex(ClientInfoContract.ClientInfoEntry.FIRST_NAME)))
            .append(" ")
            .append(curse.getString(curse.getColumnIndex(ClientInfoContract.ClientInfoEntry.LAST_NAME)));
    nameField.setText(sb.toString());
}

}

Answer 1

你是从第二个 activity 回到第一个 activity 吗？理想情况下 onCreate() 应该只用于初始化数据或附加到视图。如果您的数据正在更改，您应该在 onStart() 或 onResume()

中进行操作

因此，在您的 onStart() 方法中添加以下代码并从 onCreate() 中删除。

mInfoDBHelper = new ClientInfoDBHelper(this);
SQLiteDatabase dbReader = mInfoDBHelper.getReadableDatabase();
String[] projection = {
        ClientInfoContract.ClientInfoEntry.FIRST_NAME,
        ClientInfoContract.ClientInfoEntry.LAST_NAME,
        ClientInfoContract.ClientInfoEntry.PHONE_NUMBER,
        ClientInfoContract.ClientInfoEntry.EMAIL_ADDRESS
};

String where = ClientInfoContract.ClientInfoEntry._ID + " = ?";
String[] whereArgs = {"1"};
String sortOrder = ClientInfoContract.ClientInfoEntry.FIRST_NAME + " DESC";

mCursor = dbReader.query(
        ClientInfoContract.ClientInfoEntry.TABLE_NAME,
        projection,
        where,
        whereArgs,
        null,
        null,
        sortOrder
);
mCursor.moveToNext();
updateDisplayInfo(mCursor);

onCreate() 仅在创建视图时调用一次。然后在您的 onResume() 中，您尝试使用相同的光标，因此您不会获得更新的数据。所以你将不得不再次查询以获取更新的数据。

或者您可以 startActivityForResult() 并在 onActivityResult() 方法中通过触发新查询来更新您的数据。

直到应用程序被销毁并重新启动（sqlite 游标），文本才会更新

text is not updated until application is destroyed and restarted (sqlite cursor)

sqlite

android

cursor