Android studio 为什么我不'；t获取错误并且应用程序不'；t打开

为什么Android Studio没有检测到错误，但当我尝试在移动设备上打开应用程序时，它没有打开

只有当我在活动中对这两行进行注释时，它才会打开，但当然我没有获得完整的功能。我错过什么了吗

注释行

        spinner.findViewById(R.id.spinnerCountries);
        spinner.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,CountryData.countryNames));

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我不确定“不检测错误”是什么意思。这是否意味着它在模拟器中运行得很好，或者编译器在编译时没有给出任何错误？我没有收到Android Studio关于代码行之间错误的建议，但是如果我运行应用程序，它就不会打开，它只会在我注释有关微调器的代码行时打开。如果它不能在设备上运行，您可能希望在Android Studio内的emulator中以调试模式运行它，以查看出现了什么错误/异常。这可能会比试图读取代码来找出错误要快得多。

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;

import com.google.firebase.FirebaseException;
import com.google.firebase.auth.FirebaseAuth;

public class RegisterActivity extends AppCompatActivity {

    private Spinner spinner;
    private EditText editText;

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

        spinner.findViewById(R.id.spinnerCountries);
        spinner.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,CountryData.countryNames));

        editText = findViewById(R.id.editTextPhone);

        findViewById(R.id.buttonContinue).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String code = CountryData.countryAreaCodes[spinner.getSelectedItemPosition()];

                String number = editText.getText().toString().trim();

                    if (number.isEmpty() || number.length() < 10){
                        editText.setError("Valid number is required");
                        editText.requestFocus();
                        return;
                    }

                String phonenumber = "+" + code + number;

                Intent intent = new Intent (RegisterActivity.this,OtpActivity.class);
                intent.putExtra("phonenumber",phonenumber);
                startActivity(intent);

            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();

        if (FirebaseAuth.getInstance().getCurrentUser() !=null) {
            Intent intent = new Intent (this, MainActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);

            startActivity(intent);
        }


    }

}

public class CountryData {

    public static final String[] countryNames = 
{"Afghanistan", "Albania",
            "Algeria", "Andorra", "Angola", "Antarctica", "Argentina",
            "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan",
            "Bahrain", "Bangladesh", "Belarus", "Belgium", "Belize", "Benin",
            "Bhutan", "Bolivia", "Bosnia And Herzegovina", "Botswana",
            "Brazil", "Brunei Darussalam", "Bulgaria", "Burkina Faso",
            "Myanmar", "Burundi", "Cambodia", "Cameroon", "Canada",
            "Cape Verde", "Central African Republic", "Chad", "Chile", "China",
            "Christmas Island", "Cocos (keeling) Islands", "Colombia",
            "Comoros", "Congo", "Cook Islands", "Costa Rica", "Croatia",
            "Cuba", "Cyprus", "Czech Republic", "Denmark", "Djibouti",
            "Timor-leste", "Ecuador", "Egypt", "El Salvador",
            "Equatorial Guinea", "Eritrea", "Estonia", "Ethiopia",
            "Falkland Islands (malvinas)", "Faroe Islands", "Fiji", "Finland",
            "France", "French Polynesia", "Gabon", "Gambia", "Georgia",
            "Germany", "Ghana", "Gibraltar", "Greece", "Greenland",
            "Guatemala", "Guinea", "Guinea-bissau", "Guyana", "Haiti",
            "Honduras", "Hong Kong", "Hungary", "India", "Indonesia", "Iran",
            "Iraq", "Ireland", "Isle Of Man", "Israel", "Italy", "Ivory Coast",
            "Jamaica", "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati",
            "Kuwait", "Kyrgyzstan", "Laos", "Latvia", "Lebanon", "Lesotho",
            "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg",
            "Macao", "Macedonia", "Madagascar", "Malawi", "Malaysia",
            "Maldives", "Mali", "Malta", "Marshall Islands", "Mauritania",
            "Mauritius", "Mayotte", "Mexico", "Micronesia", "Moldova",
            "Monaco", "Mongolia", "Montenegro", "Morocco", "Mozambique",
            "Namibia", "Nauru", "Nepal", "Netherlands", "New Caledonia",
            "New Zealand", "Nicaragua", "Niger", "Nigeria", "Niue", "Korea",
            "Norway", "Oman", "Pakistan", "Palau", "Panama",
            "Papua New Guinea", "Paraguay", "Peru", "Philippines", "Pitcairn",
            "Poland", "Portugal", "Puerto Rico", "Qatar", "Romania",
            "Russian Federation", "Rwanda", "Saint Barthélemy", "Samoa",
            "San Marino", "Sao Tome And Principe", "Saudi Arabia", "Senegal",
            "Serbia", "Seychelles", "Sierra Leone", "Singapore", "Slovakia",
            "Slovenia", "Solomon Islands", "Somalia", "South Africa",
            "Korea, Republic Of", "Spain", "Sri Lanka", "Saint Helena",
            "Saint Pierre And Miquelon", "Sudan", "Suriname", "Swaziland",
            "Sweden", "Switzerland", "Syrian Arab Republic", "Taiwan",
            "Tajikistan", "Tanzania", "Thailand", "Togo", "Tokelau", "Tonga",
            "Tunisia", "Turkey", "Turkmenistan", "Tuvalu",
            "United Arab Emirates", "Uganda", "United Kingdom", "Ukraine",
            "Uruguay", "United States", "Uzbekistan", "Vanuatu",
            "Holy See (vatican City State)", "Venezuela", "Viet Nam",
            "Wallis And Futuna", "Yemen", "Zambia", "Zimbabwe"};

    public static final String[] countryAreaCodes = {"93", "355", "213",
            "376", "244", "672", "54", "374", "297", "61", "43", "994", "973",
            "880", "375", "32", "501", "229", "975", "591", "387", "267", "55",
            "673", "359", "226", "95", "257", "855", "237", "1", "238", "236",
            "235", "56", "86", "61", "61", "57", "269", "242", "682", "506",
            "385", "53", "357", "420", "45", "253", "670", "593", "20", "503",
            "240", "291", "372", "251", "500", "298", "679", "358", "33",
            "689", "241", "220", "995", "49", "233", "350", "30", "299", "502",
            "224", "245", "592", "509", "504", "852", "36", "91", "62", "98",
            "964", "353", "44", "972", "39", "225", "1876", "81", "962", "7",
            "254", "686", "965", "996", "856", "371", "961", "266", "231",
            "218", "423", "370", "352", "853", "389", "261", "265", "60",
            "960", "223", "356", "692", "222", "230", "262", "52", "691",
            "373", "377", "976", "382", "212", "258", "264", "674", "977",
            "31", "687", "64", "505", "227", "234", "683", "850", "47", "968",
            "92", "680", "507", "675", "595", "51", "63", "870", "48", "351",
            "1", "974", "40", "7", "250", "590", "685", "378", "239", "966",
            "221", "381", "248", "232", "65", "421", "386", "677", "252", "27",
            "82", "34", "94", "290", "508", "249", "597", "268", "46", "41",
            "963", "886", "992", "255", "66", "228", "690", "676", "216", "90",
            "993", "688", "971", "256", "44", "380", "598", "1", "998", "678",
            "39", "58", "84", "681", "967", "260", "263"};
}