我是android的新手，仍处于婴儿阶段。帮我解决这个问题

Question

请检查以下代码段，并帮助我解决该错误。我是android和android studio的初学者。我无法理解这里的错误，我真的需要帮助解决此问题。

  package com.ps.myapplicationeventhandling;

    import androidx.appcompat.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.TextView;

    public class MainActivity extends AppCompatActivity {
        Button btn;
        TextView txt;


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

            btn = findViewById(R.id.btn1);

    //shows error in the below line segment
            btn.setOnClickListener(new View.OnClickListener(){

    //shows error with the parameter v and alos with the @override
                @Override
                public void OnClick(View v) {
                    txt = findViewById(R.id.txt1);
                    txt.setText("You Clicked Me");
                }
            });
        }


    }

Answer 1

package com.ps.myapplicationeventhandling;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    Button btn=findViewById(R.id.btn1);
    TextView txt = findViewById(R.id.txt1);



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



        btn.setOnClickListener(new View.OnClickListener(){


            @Override
            public void OnClick(View v) {

                txt.setText("You Clicked Me");
            }
        });
    }


}