setOnClickListener让我辛苦了一天，请帮忙。:)）

Question

不知道我应该怎么解决这个问题。我是Android Studio的新手。这是我关于此活动的全部要求（称为“ Activity2”），以下是确切的问题，这就是为什么“ setOnClickListener”不起作用，它是红色，（查看“视图”）为红色，“ setText”为红色，“ intend”也为红色，红色表示存在错误。对不起，我的英语！：）））

package com.example.main;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.File;
import java.sql.DatabaseMetaData;

public class Activity2 extends AppCompatActivity {

    private Button backbutton, confbutton,btnView;
    String ipInput, portInput;
    EditText ip;
    EditText port;
    private String text;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_2);


        backbutton = findViewById(R.id.back);
        backbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                openMainActivity();
            }
        });


        ip = findViewById(R.id.IP);
        port = findViewById(R.id.Port);
        confbutton = findViewById(R.id.confirm);
        btnView = findViewById(R.id.btnView);
        confbutton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               ipInput = ip.getText().toString();
               portInput = port.getText().toString();
            }
        });`enter code here`

    }

    private void openMainActivity() {
        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
    }
    private void showToast(String text){
        this.text = text;
        Toast.makeText(this, "", Toast.LENGTH_SHORT).show();
    }

    private static final String TAG = "Activity2";



    DatabaseHelper mDatabaseHelper;


    confbutton.SetOnClickListener(new View.OnClickListener(){
      public void onClick(View view){
            String newEntry = ipInput.getText().toString();
            if (ipInput.length() != 0) {
                AddData(newEntry);
                ipInput.setText("");
            } else {
                toastMessage("You must put something in the text field!");
            }
        }
    })

    btnView.setOnClickLIstener  = new View.OnClickListener(){
        @Override
        public void onClick(View){
                Intent intent = new Intent(Activity2.this, ListDataActivity.class);
        }
    };

    public  void  AddData(String newEntry){
        boolean insertData = mDatabaseHelper.addData(newEntry);

        if(insertData){
            toastMessage("Data Succesfully Inserted!");
        }else {
            toastMessage("Something went wrong!");
        }
    }
    /**
     * customizable toast
     * @param message
     */
    private void toastMessage(String message){
        Toast.makeText(this, "message", Toast.LENGTH_SHORT).show();
    }

}