Вылет приложения Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)'

Суть программы

Суть программы заключается во вставлении текста в поля через нажатие кнопки возле поля. Текст для вставление берется с EditText сверху.

Суть ошибки

Все как бы просто, но при нажатии кнопки программа просто вылетает с вот такой ошибкой в логе: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference. При поиска я нашел информацию, что эта ошибка появляется из-за того, что я пытаюсь вызвать метод из активити, которая не используется, но я не могу понять что это за активити.

Код

Main Activity.java:

public class MainActivity extends FragmentActivity {
/**
 * The number of pages (wizard steps) to show in this demo.
 */
private static final int NUM_PAGES = 6;
/**
 * The pager widget, which handles animation and allows swiping horizontally to access previous
 * and next wizard steps.
 */
private ViewPager2 viewPager;
/**
 * The pager adapter, which provides the pages to the view pager widget.
 */
private FragmentStateAdapter pagerAdapter;
TextView dayText;
TextView text9;
TextView text10;
TextView text11;
TextView text12;
TextView text13;
TextView text14;
TextView text15;
TextView text16;
TextView text17;
TextView text18;
TextView text19;
EditText eText;
Methods methods;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_screen_slide);
    // Instantiate a ViewPager2 and a PagerAdapter.
    viewPager = findViewById(R.id.pager);
    pagerAdapter = new ScreenSlidePagerAdapter(this);
    viewPager.setAdapter(pagerAdapter);
    dayText = (TextView) findViewById(R.id.day);
    eText =   (EditText) findViewById(R.id.eText);
    text9 =  (TextView) findViewById(R.id.name9text);
    text10 = (TextView) findViewById(R.id.name10text);
    text11 = (TextView) findViewById(R.id.name11text);
    text12 = (TextView) findViewById(R.id.name12text);
    text13 = (TextView) findViewById(R.id.name13text);
    text14 = (TextView) findViewById(R.id.name14text);
    text15 = (TextView) findViewById(R.id.name15text);
    text16 = (TextView) findViewById(R.id.name16text);
    text17 = (TextView) findViewById(R.id.name17text);
    text18 = (TextView) findViewById(R.id.name18text);
    text19 = (TextView) findViewById(R.id.name19text);

    methods = new Methods();

    viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            super.onPageScrolled(position, positionOffset, positionOffsetPixels);
        }
        @Override
        public void onPageSelected(int position) {
            super.onPageSelected(position);
            methods.setDay(position, dayText);
        }
        @Override
        public void onPageScrollStateChanged(int state) {
            super.onPageScrollStateChanged(state);
        }
    });
}
public void addText(View v){
    switch (v.getId()){ //Вот при нажатии какой-либо из таких кнопок программа и вылетает(
        case R.id.addText9:
            text9.setText(eText.getText().toString());
            break;
        case R.id.addText10:
            text10.setText(eText.getText().toString());
            break;
        case R.id.addText11:
            text11.setText(eText.getText().toString());
            break;
        case R.id.addText12:
            text12.setText(eText.getText().toString());
            break;
        case R.id.addText13:
            text13.setText(eText.getText().toString());
            break;
        case R.id.addText14:
            text14.setText(eText.getText().toString());
            break;
        case R.id.addText15:
            text15.setText(eText.getText().toString());
            break;
        case R.id.addText16:
            text16.setText(eText.getText().toString());
            break;
        case R.id.addText17:
            text17.setText(eText.getText().toString());
            break;
        case R.id.addText18:
            text18.setText(eText.getText().toString());
            break;
        case R.id.addText19:
            text19.setText(eText.getText().toString());
            break;
    }
}
public void delText(View v){
    switch (v.getId()){
        case R.id.delText9:
            text9.setText("");
            break;
        case R.id.delText10:
            text10.setText("");
            break;
        case R.id.delText11:
            text11.setText("");
            break;
        case R.id.delText12:
            text12.setText("");
            break;
        case R.id.delText13:
            text13.setText("");
            break;
        case R.id.delText14:
            text14.setText("");
            break;
        case R.id.delText15:
            text15.setText("");
            break;
        case R.id.delText16:
            text16.setText("");
            break;
        case R.id.delText17:
            text17.setText("");
            break;
        case R.id.delText18:
            text18.setText("");
            break;
        case R.id.delText19:
            text19.setText("");
            break;
    }
}
@Override
public void onBackPressed() {
    if (viewPager.getCurrentItem() == 0) {
        // If the user is currently looking at the first step, allow the system to handle the
        // Back button. This calls finish() on this activity and pops the back stack.
        super.onBackPressed();
    } else {
        // Otherwise, select the previous step.
        viewPager.setCurrentItem(viewPager.getCurrentItem() - 1);
    }
}

private class ScreenSlidePagerAdapter extends FragmentStateAdapter {
    public ScreenSlidePagerAdapter(FragmentActivity fa) {
        super(fa);
    }
    @Override
    public Fragment createFragment(int position) {
        return new fragment_screen_slide_page();
    }
    @Override
    public int getItemCount() {
        return NUM_PAGES;
    }
}
}

Methods.java:

public class Methods {

public void setDay(int position, TextView dayText){
    switch (position){
        case 0:
            dayText.setText("Monday");
            break;
        case 1:
            dayText.setText("Tuesday");
            break;
        case 2:
            dayText.setText("Wednesday");
            break;
        case 3:
            dayText.setText("Thursday");
            break;
        case 4:
            dayText.setText("Friday");
            break;
        case 5:
            dayText.setText("Saturday");
            break;
    }
}
}

В этом классе пока есть только один метод, но он дополнялся бы. Этот класс не имеет отношения к ошибке и был добавлен в вопрос только для полноты картины.

activity_screen_slide.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
    android:id="@+id/day"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Day"
    android:gravity="center"
    android:background="@color/white"></TextView>
<EditText
    android:id="@+id/eText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="Enter Name"
    android:background="@color/white"></EditText>

<androidx.viewpager2.widget.ViewPager2
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" /></LinearLayout>

activity_screen_slide_page.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/white"
android:id="@+id/ll">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name9"
    android:layout_weight="9">

    <TextView
        android:id="@+id/t9"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="09:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:id="@+id/name9text"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:gravity=""
        android:textSize="20sp"></TextView>
    <ImageButton
        android:id="@+id/addText9"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>

    <ImageButton
        android:id="@+id/delText9"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name10"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t10"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="10:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name10text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText10"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText10"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name11"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t11"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="11:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name11text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText11"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText11"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name12"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t12"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="12:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name12text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText12"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText12"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name13"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t13"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="13:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name13text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText13"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText13"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name14"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t14"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="14:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name14text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText14"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText14"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name15"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t15"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="15:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name15text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText15"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText15"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name16"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t16"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="16:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name16text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText16"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText16"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name17"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t17"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="17:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name17text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText17"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText17"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name18"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t18"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="18:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name18text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText18"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText18"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:id="@+id/name19"
    android:layout_weight="9">
    <TextView
        android:id="@+id/t19"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="19:00"
        android:textSize="20sp"
        android:gravity="center"
        ></TextView>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_weight="10000"
        android:id="@+id/name19text"
        android:textSize="20sp"
        android:gravity=""></TextView>
    <ImageButton
        android:id="@+id/addText19"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="addText"
        android:src="@android:drawable/ic_input_add"
        android:text="Add"
        android:textAllCaps="false"></ImageButton>
    <ImageButton
        android:id="@+id/delText19"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_weight="1"
        android:background="@color/white"
        android:onClick="delText"
        android:src="@android:drawable/ic_delete"
        android:text="Del"
        android:textAllCaps="false"></ImageButton>
</LinearLayout></LinearLayout>

Здесь много повторяющегося кода, ибо это почти таблица

Надеюсь на вашу помощь.