Cannot resolve symbol error in while change text on Text view by button in Android Studio

Question

Help me I'm trying to develop app for Sudoku Im stuck at this Im just Bsc First yr guy don't know anything

Here My Xml code for my TextView Code

<TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/change"
        android:text="Not Changed"/>

Here is my XML code for Button

    <Button
    android:id="@+id/btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="24dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:text="Test Button"
    app:layout_constraintBottom_toTopOf="@+id/btn_sample"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent" />

Here is My Java Code

public void btn(View view) {
        TextView t=(TextView)findViewById(change);
        t.setText("Changed");
}

If I succeed it will Motivate me and my CLG mates I'm noob here sorry for bad English Thanks in Advance

Update : Answer is Solved New code for Button

<Button
    android:id="@+id/btn"
    android:onClick="btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="24dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:text="Test Button"
    app:layout_constraintBottom_toTopOf="@+id/btn_sample"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent" />

New Updated Code for Java

public void btn(View view) {
        TextView t=(TextView)findViewById(R.id.change);
        t.setText("Changed");
}

Thanks to nilesh-rathod

Answer 1

findViewById()

Finds a view that was identified by the android:id XML attribute that was processed in onCreate(Bundle).

Use this

TextView t=(TextView)findViewById(R.id.change);

Instead of this

TextView t=(TextView)findViewById(change);

EDIT

If you want to add click event of you Button than please use below edit

Add android:onclick="btn" in your Button

<Button
    android:id="@+id/btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="24dp"
    android:layout_marginEnd="8dp"
    android:layout_marginStart="8dp"
    android:onclick="btn"
    android:text="Test Button"
    app:layout_constraintBottom_toTopOf="@+id/btn_sample"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent" />