Java 首先获取值，然后在onCreate（）方法中检查null

在myLoginActivity.java中，我从另一个活动中检索数据并放入TextView，同时在onCreate（）方法中检查同一个TextView的空值

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_login);

        btnLogout = (Button) findViewById(R.id.btnLogout);
        btnCamera = (Button) findViewById(R.id.btnCamera);
        btnGallery = (Button) findViewById(R.id.btnGallery);

            txtDeviceID = (TextView) findViewById(R.id.txtDeviceID);
            txtEmailID = (TextView) findViewById(R.id.txtEmailID);      
            txtEvent = (TextView) findViewById(R.id.txtEvent);  
            txtOperative = (TextView) findViewById(R.id.txtOperative);
            txtEventOperator = (TextView) findViewById(R.id.txtEventOperator);

             Intent intent = getIntent();
             deviceID = intent.getStringExtra("deviceID");
             emailID = intent.getStringExtra("emailID");
             event = intent.getStringExtra("name"); 
             operative = intent.getStringExtra("firstName");

             txtDeviceID.setText(deviceID);
             txtEmailID.setText(emailID);
             txtEvent.setText(event);
             Log.d("LA...event", txtEvent.getText().toString());
             txtOperative.setText(operative);
             Log.d("LA...operative", txtOperative.getText().toString());
             txtEventOperator.setText(event + "  " + operative);

             strEvent = txtEvent.getText().toString();
             strOperative = txtOperative.getText().toString();

            // Dialog
                final AlertDialog.Builder adb = new AlertDialog.Builder(this);
                AlertDialog ad = adb.create();

                // new Class DB
                final myDBClass myDb = new myDBClass(this);

                // Save Data
                long saveStatus = myDb.InsertData(
                            txtDeviceID.getText().toString(),
                            txtEmailID.getText().toString(),
                            txtEvent.getText().toString(),
                            txtOperative.getText().toString(),
                            txtEventOperator.getText().toString()
                            );

                if(saveStatus <=  0)
                {
                  ad.setMessage("Error!! ");
                  ad.show();
                  return;
                }   

                // Show Data
                String arrData[] = myDb.SelectData();
                if(arrData != null)
                {
                    txtDeviceID.setText(arrData[1]);
                    txtEmailID.setText(arrData[2]);
                    txtEvent.setText(arrData[3]);
                    txtOperative.setText(arrData[4]);
                    txtEventOperator.setText(arrData[5]);
                }  

                if(txtEvent.getText().toString().equals("") && txtOperative.getText().toString().equals(""))
                {

                    Intent intentCall = new Intent(LoginActivity.this, LicenseListActivity.class);
                    startActivity(intentCall);
                }

     }

我希望LoginActivity.java调用时首先从另一个活动检索数据，然后设置为TextView，然后检查条件

我已经为所有内容编写了代码-以检查条件、检索值以及将值设置为文本视图

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_login);

        btnLogout = (Button) findViewById(R.id.btnLogout);
        btnCamera = (Button) findViewById(R.id.btnCamera);
        btnGallery = (Button) findViewById(R.id.btnGallery);

            txtDeviceID = (TextView) findViewById(R.id.txtDeviceID);
            txtEmailID = (TextView) findViewById(R.id.txtEmailID);      
            txtEvent = (TextView) findViewById(R.id.txtEvent);  
            txtOperative = (TextView) findViewById(R.id.txtOperative);
            txtEventOperator = (TextView) findViewById(R.id.txtEventOperator);

             Intent intent = getIntent();
             deviceID = intent.getStringExtra("deviceID");
             emailID = intent.getStringExtra("emailID");
             event = intent.getStringExtra("name"); 
             operative = intent.getStringExtra("firstName");

             txtDeviceID.setText(deviceID);
             txtEmailID.setText(emailID);
             txtEvent.setText(event);
             Log.d("LA...event", txtEvent.getText().toString());
             txtOperative.setText(operative);
             Log.d("LA...operative", txtOperative.getText().toString());
             txtEventOperator.setText(event + "  " + operative);

             strEvent = txtEvent.getText().toString();
             strOperative = txtOperative.getText().toString();

            // Dialog
                final AlertDialog.Builder adb = new AlertDialog.Builder(this);
                AlertDialog ad = adb.create();

                // new Class DB
                final myDBClass myDb = new myDBClass(this);

                // Save Data
                long saveStatus = myDb.InsertData(
                            txtDeviceID.getText().toString(),
                            txtEmailID.getText().toString(),
                            txtEvent.getText().toString(),
                            txtOperative.getText().toString(),
                            txtEventOperator.getText().toString()
                            );

                if(saveStatus <=  0)
                {
                  ad.setMessage("Error!! ");
                  ad.show();
                  return;
                }   

                // Show Data
                String arrData[] = myDb.SelectData();
                if(arrData != null)
                {
                    txtDeviceID.setText(arrData[1]);
                    txtEmailID.setText(arrData[2]);
                    txtEvent.setText(arrData[3]);
                    txtOperative.setText(arrData[4]);
                    txtEventOperator.setText(arrData[5]);
                }  

                if(txtEvent.getText().toString().equals("") && txtOperative.getText().toString().equals(""))
                {

                    Intent intentCall = new Intent(LoginActivity.this, LicenseListActivity.class);
                    startActivity(intentCall);
                }

     }

但是每当我调用LoginActivity.java时，它总是先检查条件，但我想先获取并设置TextView的值，然后在onCreate（）方法中检查条件

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_login);

        btnLogout = (Button) findViewById(R.id.btnLogout);
        btnCamera = (Button) findViewById(R.id.btnCamera);
        btnGallery = (Button) findViewById(R.id.btnGallery);

            txtDeviceID = (TextView) findViewById(R.id.txtDeviceID);
            txtEmailID = (TextView) findViewById(R.id.txtEmailID);      
            txtEvent = (TextView) findViewById(R.id.txtEvent);  
            txtOperative = (TextView) findViewById(R.id.txtOperative);
            txtEventOperator = (TextView) findViewById(R.id.txtEventOperator);

             Intent intent = getIntent();
             deviceID = intent.getStringExtra("deviceID");
             emailID = intent.getStringExtra("emailID");
             event = intent.getStringExtra("name"); 
             operative = intent.getStringExtra("firstName");

             txtDeviceID.setText(deviceID);
             txtEmailID.setText(emailID);
             txtEvent.setText(event);
             Log.d("LA...event", txtEvent.getText().toString());
             txtOperative.setText(operative);
             Log.d("LA...operative", txtOperative.getText().toString());
             txtEventOperator.setText(event + "  " + operative);

             strEvent = txtEvent.getText().toString();
             strOperative = txtOperative.getText().toString();

            // Dialog
                final AlertDialog.Builder adb = new AlertDialog.Builder(this);
                AlertDialog ad = adb.create();

                // new Class DB
                final myDBClass myDb = new myDBClass(this);

                // Save Data
                long saveStatus = myDb.InsertData(
                            txtDeviceID.getText().toString(),
                            txtEmailID.getText().toString(),
                            txtEvent.getText().toString(),
                            txtOperative.getText().toString(),
                            txtEventOperator.getText().toString()
                            );

                if(saveStatus <=  0)
                {
                  ad.setMessage("Error!! ");
                  ad.show();
                  return;
                }   

                // Show Data
                String arrData[] = myDb.SelectData();
                if(arrData != null)
                {
                    txtDeviceID.setText(arrData[1]);
                    txtEmailID.setText(arrData[2]);
                    txtEvent.setText(arrData[3]);
                    txtOperative.setText(arrData[4]);
                    txtEventOperator.setText(arrData[5]);
                }  

                if(txtEvent.getText().toString().equals("") && txtOperative.getText().toString().equals(""))
                {

                    Intent intentCall = new Intent(LoginActivity.this, LicenseListActivity.class);
                    startActivity(intentCall);
                }

     }

@覆盖
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
getWindow（）.addFlags（WindowManager.LayoutParams.FLAG\u保持屏幕打开）；
setContentView（R.layout.activity\u登录）；
btnLogout=（按钮）findViewById（R.id.btnLogout）；
btnCamera=（按钮）findViewById（R.id.btnCamera）；
btnGallery=（按钮）findViewById（R.id.btnGallery）；
txtDeviceID=（TextView）findViewById（R.id.txtDeviceID）；
txtEmailID=（TextView）findViewById（R.id.txtEmailID）；
txtEvent=（TextView）findViewById（R.id.txtEvent）；
txtOperative=（TextView）findViewById（R.id.txtOperative）；
txtEventOperator=（TextView）findViewById（R.id.txtEventOperator）；
Intent=getIntent（）；
deviceID=intent.getStringExtra（“deviceID”）；
emailID=intent.getStringExtra（“emailID”）；
event=intent.getStringExtra（“名称”）；
操作=intent.getStringExtra（“名字”）；
txtDeviceID.setText（deviceID）；
txtEmailID.setText（emailID）；
txtEvent.setText（事件）；
Log.d（“LA…event”，txtEvent.getText（）.toString（））；
txtOperative.setText（可操作）；
Log.d（“LA…operative”，txtOperative.getText（）.toString（））；
txtEventOperator.setText（事件+“”+可操作）；
strEvent=txtEvent.getText（）.toString（）；
strOperative=txtOperative.getText（）.toString（）；
//对话
final AlertDialog.Builder adb=新建AlertDialog.Builder（此）；
AlertDialog ad=adb.create（）；
//新类数据库
最终myDBClass myDb=新的myDBClass（此）；
//保存数据
long saveStatus=myDb.InsertData(
txtDeviceID.getText（）.toString（），
txtEmailID.getText（）.toString（），
txtEvent.getText（）.toString（），
txtOperative.getText（）.toString（），
txtEventOperator.getText（）.toString（）
);
如果（saveStatus，您可以将您的条件放在onStart方法中

@Override
    public void onStart() {
if(condition)

}

每当创建活动时，先调用Create方法，然后再调用onStart方法。
那么问题出在哪里？我该如何处理？但您尝试先将其设置为Textview，然后进行检查，您能更好地描述您的问题吗？