问致命异常问题: Android应用启动执行时main

EN

    < ?xml version="1.0" encoding="utf-8"? >
    <androidx.constraintlayout.widget.ConstraintLayout 
    xmlns:android`="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/fondo"
    tools:context="menu.MainActivity">

<Button
    android:id="@+id/lisaid"
    android:layout_width="225dp"
    android:layout_height="63dp"
    android:layout_marginStart="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="100dp"
    android:background="@drawable/fondoet"
    android:onClick="listar"
    android:text="@string/listar"
    android:textColor="@color/colorPrimaryDark"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.588"
    app:layout_constraintStart_toStartOf="parent"
    tools:text="@string/listar" />

<Button
    android:id="@+id/consultar"
    android:layout_width="225dp"
    android:layout_height="63dp"
    android:layout_marginStart="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="32dp"
    android:background="@drawable/fondoet"
    android:onClick="consulta"
    android:text="@string/CONSULTA"
    android:textColor="@color/colorPrimaryDark"
    app:layout_constraintBottom_toTopOf="@+id/lisaid"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.588"
    app:layout_constraintStart_toStartOf="parent"
    tools:text="@string/CONSULTA" />

<Button
    android:id="@+id/crear"
    android:layout_width="225dp"
    android:layout_height="63dp"
    android:layout_marginStart="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="32dp"
    android:background="@drawable/fondoet"
    android:onClick="ejecucion"
    android:text="@string/CREAR"
    android:textColor="@color/colorPrimaryDark"
    app:layout_constraintBottom_toTopOf="@+id/consultar"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.588"
    app:layout_constraintStart_toStartOf="parent"
    tools:text="@string/CREAR" />

<TextView
    android:id="@+id/textView9"
    android:layout_width="338dp"
    android:layout_height="64dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="8dp"
    android:background="@drawable/fondoet"
    android:gravity="center"
    android:text="@string/BIENVENIDO"
    android:textColor="@color/colorPrimaryDark"
    android:textColorHighlight="@color/colorPrimary"
    android:textSize="36sp"
    app:layout_constraintBottom_toTopOf="@+id/textView10"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:text="@string/BIENVENIDO" />

<TextView
    android:id="@+id/textView10"
    android:layout_width="322dp"
    android:layout_height="72dp"
    android:layout_marginStart="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="30dp"
    android:background="@drawable/fondoet"
    android:gravity="center"
    android:text="@string/datos"
    android:textColor="@color/colorPrimaryDark"
    android:textColorHighlight="@color/colorPrimary"
    android:textSize="18sp"
    app:layout_constraintBottom_toTopOf="@+id/crear"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.627"
    app:layout_constraintStart_toStartOf="parent"
    tools:text="@string/datos" />

    public class MainActivity extends AppCompatActivity
{

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

        AdminSQLiteOpenHelper conn=new AdminSQLiteOpenHelper(this,"bd_usuarios",null,1);
    }


    public void ejecucion (View view)
    {
        Intent miintent= null;
        switch(view.getId())
        {
            case R.id.crear:miintent=new Intent(MainActivity.this,Ejecucion.class);
            break;
        }
        if (miintent!=null)
        {
            startActivity(miintent);
        }

    }
    public void consulta (View view)
    {
        Intent miintent= null;
        switch(view.getId())
        {
            case R.id.consultar:miintent=new Intent(MainActivity.this,consulta1.class);
                break;
        }
        if (miintent!=null)
        {
            startActivity(miintent);
        }
    }
    public void listar (View view)
    {
        Intent miintent= null;
        switch(view.getId())
        {
            case R.id.lisaid:miintent=new Intent(MainActivity.this, listausuarios.class);

        }
        if (miintent!=null)
        {
            startActivity(miintent);
        }
    }
}