Question

我已经编写了一种在SQLite中更新用户密码的方法。

该方法是 updatePassword（）

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当这个方法运行时，如果我注释掉SQL语句，它将显示Log，这表明它正在运行if语句而没有问题？

我也有toasts来显示if和#clans中使用的变量，但是它们显示了所需的值而且不是null！

一旦我回复public class changePassword extends Activity { SQLiteDatabase checkDB; //Load session name String sessionName; String sessionPassword; String currentPasswordString; String newPassword1String; String newPassword2String; //Load text fields EditText currentPassword; EditText newPassword1; EditText newPassword2; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.changepassword); Button changePassword = (Button)findViewById(R.id.changePasswordButton); //Load session name SharedPreferences preferences = getSharedPreferences("temp", getApplicationContext().MODE_PRIVATE); sessionName = preferences.getString("sessionName", ""); sessionPassword = preferences.getString("sessionPassword", ""); currentPassword = (EditText)findViewById(R.id.currentPassword); newPassword1 = (EditText)findViewById(R.id.newpassword1); newPassword2 = (EditText)findViewById(R.id.newpassword2); } //Mismatched password checking public void updatePassword(View v) { currentPasswordString = currentPassword.getText().toString(); newPassword1String = newPassword1.getText().toString(); newPassword2String = newPassword2.getText().toString(); Toast.makeText(changePassword.this, sessionName.toString(), Toast.LENGTH_LONG).show(); Toast.makeText(changePassword.this, newPassword2String.toString(), Toast.LENGTH_LONG).show(); if (currentPasswordString.equals(sessionPassword)) { if (newPassword1String.equals(newPassword2String)) { checkDB.execSQL("UPDATE Students SET Student_Password=" + newPassword2String + "WHERE CNumber=" + sessionName); Log.d("Password", "Changed"); } } } }，此LogCat错误就会显示：

execSQL

Answer 1

如果您注释掉

checkDB.execSQL("UPDATE Students SET Student_Password=" + newPassword2String + "WHERE CNumber=" + sessionName);

行并运行到日志语句，然后checkDB为null。

您在哪里打开/初始化数据库？

NullPointerException，即使变量不为空

1 个答案: