无法执行安卓方法:onClick?

Question

我正在尝试通过验证数据库中已有的电子邮件和密码来制作登录页面。但是，会发生致命的异常。

这是我的登录活动.java，myDbHelper.java，activity_login.xml和logcat错误。

日志猫错误如下：

FATAL EXCEPTION:main
Process:no.nordicsemi.android.nrftoolbox,PID:9052
java.lang.IllegalStateException:
Could not
execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:4785)
at android.view.View$PerformClick.run(View.java:19888)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5276)
at java.lang.reflect.Method.invoke(
Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:911)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)
Caused by:java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(
Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4785) 
at android.view.View$PerformClick.run(View.java:19888) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5276) 
at java.lang.reflect.Method.invoke(
Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:911) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706) 
Caused by:android.database.sqlite.SQLiteException:near ".":
syntax error(code 1):,while compiling:select *
from contacts
where email = android.support.v7.widget.AppCompatEditText
{
1d 2 b15f4 VFED..CL ........ 0, 72 - 1080, 208 #7f 090085 app:
id / editText_mail
}
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(
Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1316)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1255)
at no.nordicsemi.android.nrftoolbox.myDbAdapter.getEmail(myDbAdapter.java:208)
at no.nordicsemi.android.nrftoolbox.LoginActivity.login(LoginActivity.java:41)

我的登录活动.java：

public class LoginActivity extends AppCompatActivity {
TextView email;
TextView pass;
private no.nordicsemi.android.nrftoolbox.myDbAdapter mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
email = (TextView) findViewById(R.id.editText_mail);
pass = (TextView) findViewById(R.id.editText_pass);
mydb = new no.nordicsemi.android.nrftoolbox.myDbAdapter(this);
}
public void register(View v) {
Intent goToSecond = new Intent();
goToSecond.setClass(this, Register_Page.class);
startActivity(goToSecond);
}
public void login(View v) {
Cursor c1 = mydb.getEmail(email);
Cursor c2 = mydb.getpass(pass);
if (c1 != null & c2 != null) {
Intent goToSecond = new Intent();
goToSecond.setClass(this, Profile.class);
startActivity(goToSecond);
} else
message(getApplicationContext(), "not valid user");
}
}

myDbHelper.java(getEmail和getpass方法)如下：

public Cursor getEmail(TextView email)
{
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor= db.rawQuery( "select * from contacts where email="+email+"",null);
return cursor;
}
public Cursor getpass(TextView pass)
{
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor= db.rawQuery( "select * from contacts where password="+pass+"",null);
return cursor;
}

是什么导致应用程序崩溃？
可能的错误在哪里？

我做了建议的更改.但是现在日志猫错误显示：

Caused by: android.database.sqlite.SQLiteException: near "@gmail": syntax error (code 1): , while compiling: select * from contacts where email=[e-mail]    

我该如何纠正此问题？

Answer 1

EditText email = (EditText) findViewById(R.id.editText_mail);
EditText  pass = (EditText) findViewById(R.id.editText_pass);
Cursor c1 = mydb.getEmail(email.getText());
Cursor c2 = mydb.getpFass(pass.getText());
AND  
Cursor cursor= db.rawQuery( "select * from contacts where email='"+email.getText().toString()+"'",null);
Cursor cursor= db.rawQuery( "select * from contacts where password='"+pass.getText().toString()+"'",null);

Answer 2

• 纠正SELECT语句。

SQLiteException： near "."： 语法错误 (代码 1)： ， 编译时：

使用getText().toString().您的SELECT声明将是。

Cursor cursor= db.rawQuery( "select * from contacts  where email='"+email.getText().toString()+"'",null);  

和

Cursor cursor= db.rawQuery( "select * from contacts  where password='"+pass.getText().toString()+"'",null); 

Answer 3

是什么导致应用程序崩溃？可能的错误在哪里？

这是导致问题的email和pass，因为SQL查询始终在字符串中，并且您的email和pass不是String而是TextView，因此崩溃

将myDbHelper.java更改为：

public Cursor getEmail(TextView email)
{
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor= db.rawQuery( "select * from contacts where email='"+email.getText().toString()+"'",null);    //Added getText().toString()
return cursor;
}
public Cursor getpass(TextView pass)
{
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor= db.rawQuery( "select * from contacts where password='"+pass.getText()+"'",null);    //Added getText().toString()
return cursor;
}