Question

我为后端注册用户编写了一种方法。填写所有文本字段后，我可以注册用户。我的问题是，当我点击带有空文本字段的应用程序崩溃的按钮时，我写了一个if语句来检查空文本字段并显示祝酒词。

public void RegisterButtonPressed(View view) {

  if(email.getText() == null || password.getText() == null || username.getText() == null){

      Toast.makeText(this, "Every Fileds should be filled", Toast.LENGTH_SHORT).show();

  } else {

      if(email.getText() != null && password.getText() != null && username.getText() != null) {

          final String emailS = email.getText().toString();
          final String passwordS = password.getText().toString();
          String usernameS = username.getText().toString();

          BackendlessUser user = new BackendlessUser();

          user.setEmail(emailS);
          user.setPassword(passwordS);
          user.setProperty("name",usernameS);
          user.setProperty("Avatar","");

          Backendless.UserService.register(user, new AsyncCallback<BackendlessUser>() {
              @Override
              public void handleResponse(BackendlessUser backendlessUser) {

                  Toast.makeText(RegisterActivity.this, "User Registration Successfull", Toast.LENGTH_SHORT).show();

                  Backendless.UserService.login(emailS, passwordS, new AsyncCallback<BackendlessUser>() {
                      @Override
                      public void handleResponse(BackendlessUser backendlessUser) {

                          Toast.makeText(RegisterActivity.this, "Logged", Toast.LENGTH_SHORT).show();
                      }

                      @Override
                      public void handleFault(BackendlessFault backendlessFault) {

                          Toast.makeText(RegisterActivity.this, "User Login Unsuccessfull: " + backendlessFault.getDetail(), Toast.LENGTH_SHORT).show();

                      }
                  });

              }

              @Override
              public void handleFault(BackendlessFault backendlessFault) {

                  Toast.makeText(RegisterActivity.this, "User Registration Unsuccesful: " + backendlessFault.getDetail(), Toast.LENGTH_SHORT).show();

              }
          });

      }

  }
}

error log

Answer 1

你应该检查

if(TextUtils.isEmpty(email.getText()))

而不是

if (email.getText() == null)

根据我的经验， getText（）如果为空则不返回null，而是空字符串a.k.a＆＃34;＆＃34;

然而，

TextUtils.isEmpty（）将检查null和＆＃34;＆＃34;作为空字符串

Answer 2

您只是检查字符串是否为空。如果它是空的，那么你的if语句将无法捕获，并且仍然可能导致崩溃。你也应该检查空字符串。

if(email.getText() == null || email.getText().length() == 0 || 
password.getText() == null || password.getText.length() == 0 || 
username.getText() == null || username.getText.length() == 0){

  Toast.makeText(this, "Every Fileds should be filled", Toast.LENGTH_SHORT).show();
}

单击空文本字段时应用程序崩溃

2 个答案: