Question

我正在尝试使用Realm数据库登录和注册用户。但是我得到的错误如下：

尝试在空对象引用上调用虚方法'void io.realm.Realm.beginTransaction（）'

是的，有人能帮帮我吗？

以下是我的注册和登录代码..

注册代码：

public class RegisterActivity extends AppCompatActivity {

private static final String TAG = "Register";
EditText mEditTextFirstName, mEditTextLastName, mEditTextEmail,mEditTextPassword,mEditTextConfirmPassword;
Button mButtonSignUp;
Realm realm;
private MyRealmObject myRealmObject;

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

    try {
        realm = Realm.getInstance(getApplicationContext());
    } catch (Exception e) {
        e.printStackTrace();
    }

    mEditTextFirstName = (EditText) findViewById(R.id.edtfirstname);
    mEditTextLastName= (EditText) findViewById(R.id.edtlastname);
    mEditTextEmail = (EditText) findViewById(R.id.edtemail);
    mEditTextPassword = (EditText) findViewById(R.id.edtpassword);
    mEditTextConfirmPassword = (EditText) findViewById(R.id.edtconfirm);
    mButtonSignUp = (Button) findViewById(R.id.btnsignup);


    mButtonSignUp.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mEditTextFirstName.length() == 0) {
                showSnackBar("Enter FirstName");
                mEditTextFirstName.requestFocus();
            } else if (mEditTextLastName.length() == 0) {
                showSnackBar("Enter LastName");
                mEditTextEmail.requestFocus();
            } else if (mEditTextEmail.length() ==0) {
                showSnackBar("Enter a valid email");
                mEditTextEmail.requestFocus();
            }else if (mEditTextPassword.length() ==0) {
                showSnackBar("Enter a valid password");
                mEditTextPassword.requestFocus();
            }else if (mEditTextConfirmPassword.length() ==0) {
                        showSnackBar("Enter a valid Password");
                        mEditTextPassword.requestFocus();
            } else {

                try{

                    realm.beginTransaction();

                    myRealmObject = realm.createObject(MyRealmObject.class);
                    myRealmObject.setFirstName(mEditTextFirstName.getText().toString());
                    myRealmObject.setLastName(mEditTextLastName.getText().toString());
                    myRealmObject.setEmail(mEditTextEmail.getText().toString());
                    myRealmObject.setPassword(mEditTextPassword.getText().toString());
                    myRealmObject.setConfirmPassword(mEditTextConfirmPassword.getText().toString());


                    realm.commitTransaction();

                    showSnackBar("Save Success");


                } catch (RealmPrimaryKeyConstraintException e){
                    e.printStackTrace();
                    showSnackBar("User found on db.");
                }

            }
        }
    });


}

private void showSnackBar(String msg) {
    try {
        Snackbar.make(findViewById(R.id.relativeregister), msg, Snackbar.LENGTH_SHORT).show();
    } catch (NullPointerException e) {
        e.printStackTrace();
        Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
    }
}



}

以下是我的登录代码..

public class LoginActivity extends AppCompatActivity {

private static final String TAG = "Home";
private EditText mEditTextEmail, mEditTextPassword;
private TextView txtlogin;
TextView Create;
private Realm realm;
private MyRealmObject myRealmObject;

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

    try {
        realm = Realm.getInstance(getApplicationContext());
    } catch (Exception e) {
        e.printStackTrace();
    }

    mEditTextEmail = (EditText) findViewById(R.id.edtemail);
    mEditTextPassword = (EditText) findViewById(R.id.edtpswrd);
    txtlogin = (TextView) findViewById(R.id.txtlogin);
    Create = (TextView) findViewById(R.id.txtcreate);


    Create.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent i = new Intent(LoginActivity.this, RegisterActivity.class);
            startActivity(i);

        }
    });

    txtlogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mEditTextEmail.length() == 0) {
                showSnackBar("Enter EMAIL");
                mEditTextEmail.requestFocus();
            } else if (mEditTextPassword.length() == 0) {
                showSnackBar("Enter password");
                mEditTextPassword.requestFocus();
                Intent i = new Intent(LoginActivity.this, MainActivity.class);
                startActivity(i);


            }
        }

         private boolean checkUser(String email,String password) {
                RealmResults<MyRealmObject> realmObjects = realm.where(MyRealmObject.class).findAll();
               for (MyRealmObject myRealmObject : realmObjects) {
                   if (email.equals(myRealmObject.getEmail()) && password.equals(myRealmObject.getPassword())) {
                        Log.e(TAG, myRealmObject.getEmail());
                        return true;
                    }
    }


                Log.e(TAG, String.valueOf(realm.where(MyRealmObject.class).contains("Email", email)));
               return false;
          }



        private void showSnackBar(String msg) {
            try {
                Snackbar.make(findViewById(R.id.relativelogin), msg, Snackbar.LENGTH_SHORT).show();
            } catch (NullPointerException e) {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
            }
        }


    });
}

我的RealmObject类：

public class MyRealmObject extends RealmObject {
private String FirstName, LastName,ConfirmPassword;
@PrimaryKey
private String Email;
private String Password;

public MyRealmObject() {
}

public String getFirstName() {
    return FirstName;
}

public void setFirstName(String FirstName) {
    this.FirstName = FirstName;
}

public String getLastName() {
    return LastName;
}

public void setLastName(String LastName) {
    this.LastName = LastName;
}

public String getEmail() {
    return Email;
}

public void setEmail(String email) {
    this.Email = Email;
}

public String getPassword() {
    return Password;
}

public void setPassword(String password) {
    this.Password = password;
}

public String getConfirmPassword() {
    return getConfirmPassword();
}

public void setConfirmPassword(String confirmPassword) {
    this.ConfirmPassword = confirmPassword;
}

}

有人指导我哪里错了。

提前致谢..

Answer 1

请注意，不推荐使用Realm.getInstance(context)。您应该在应用程序类中设置默认的RealmConfiguration，并使用Realm.getDefaultInstance()，如下所述：https://realm.io/docs/java/latest/#controlling-the-lifecycle-of-realm-instances

从快速浏览一下，你的代码不应该抛出异常，但是在try / catch中包装realm = Realm.getInstance(getApplicationContext())是危险的，因为如果方法抛出，你将得到你看到的NullPointer。我会删除它。

使用Realm注册和登录

1 个答案: