java - 为什么我的 android 应用程序在我向数据库填写一个简单的问题表单时返回到以前的 Activity ？

Question

我正在尝试构建一个测验应用程序，管理员将在其中创建管理 Activity 中的问题，这些问题将在另一个 Activity 中显示为测验考试。当我尝试通过单击管理 Activity 中的创建问题按钮来填写表格时，我的应用程序将返回到之前的 Activity (管理登录 Activity )这是 AdminActivity 的代码:

public class AdminActivity extends AppCompatActivity {
Button btnCreateQuestion, btnReadQuestion, btnDeleteQuestion;
EditText editTextQuestion, editTextOption1, editTextOption2, editTextOption3, editTextOption4,
    editTextAnswerNo,editTextChapterNo;
QuizDbHelper db;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_admin);
    btnCreateQuestion = findViewById(R.id.btnCreateQuestion);
    btnReadQuestion = findViewById(R.id.btnReadQuestions);
    btnDeleteQuestion = findViewById(R.id.btnDeleteQuestions);
    editTextQuestion = findViewById(R.id.editTextQuestion);
    editTextOption1 = findViewById(R.id.editTextOption1);
    editTextOption2 = findViewById(R.id.editTextOption2);
    editTextOption3 = findViewById(R.id.editTextOption3);
    editTextOption4 = findViewById(R.id.editTextOption4);
    editTextAnswerNo = findViewById(R.id.editTextAnswerNo);
    editTextChapterNo = findViewById(R.id.editTextChapterNo);
    db = new QuizDbHelper(this);

    btnCreateQuestion.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String question = editTextQuestion.getText().toString();
            String option1 = editTextOption1.getText().toString();
            String option2 = editTextOption2.getText().toString();
            String option3 = editTextOption3.getText().toString();
            String option4 = editTextOption4.getText().toString();
            Integer answerNo = Integer.parseInt(editTextAnswerNo.getText().toString());
            String chapterName = editTextAnswerNo.getText().toString();
            if( question != "" && option1 != "" && option2 != "" && option3 != "" && option4 != "" && answerNo!= null && chapterName != ""){
                Question q = new Question(question,option1,option2,option3,option4,answerNo,chapterName);
                db.addQuestion(q);
                Toast.makeText(AdminActivity.this,"Question Added", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(AdminActivity.this,"Please fill up", Toast.LENGTH_SHORT).show();
            }

        }
    });
    btnReadQuestion.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
           ArrayList<Question> allQuestions = db.getAllQuestions();
           if(allQuestions.size()< 1){
                Toast.makeText(AdminActivity.this,"No questions in the Database", Toast.LENGTH_SHORT).show();
           }else {
               StringBuffer buffer = new StringBuffer();
               for (Question q: allQuestions) {
                   buffer.append("Question : " + q.getQuestion() + "\n" );
                   buffer.append("Option1:  " + q.getOption1() + "\n");
                   buffer.append("Option2:  " + q.getOption2() + "\n");
                   buffer.append("Option3:  " + q.getOption3() + "\n");
                   buffer.append("Option4:  " + q.getOption4() + "\n");
                   buffer.append("Answer No:  " + q.getAnswerNo() + "\n");
                   buffer.append("Option4:  " + q.getChapterName() + "\n\n");
               }

               AlertDialog.Builder builder = new AlertDialog.Builder(AdminActivity.this);
               builder.setCancelable(true);
               builder.setTitle("Questions");
               builder.setMessage(buffer.toString());
               builder.show();
           }
        }
    });
    btnDeleteQuestion.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
}}

有什么线索吗？提前致谢。

Answer 1

检查您的 Activity 类的 onCreate 函数，您是否已经初始化了您的 EditText 和 Button。

此外，您必须按以下方式更改您的条件:

if(!question.equalsIgnoreCase("") && !option1.equalsIgnoreCase("") && !option2.equalsIgnoreCase("") && !option3.equalsIgnoreCase("") && !option4.equalsIgnoreCase("") && answerNo != 0 && !chapterName.equalsIgnoreCase("")

因为，== 测试引用相等性(它们是否是同一个对象)。

而 equalsIgnoreCase() 在比较两个字符串时忽略大小写。