安卓Java主页面的编写

package com.example.first;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private Button mbtnTextView;
    private Button mbtnButton;
    private Button mbtnEditText;
    private Button mbtnRadioButton;

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

        mbtnTextView = findViewById(R.id.btn_textview);
        mbtnButton=findViewById(R.id.btn_button);
        mbtnEditText=findViewById(R.id.btn_edittext);
        mbtnRadioButton=findViewById((R.id.btn_radioButton));
        setListeners();
    }

    //听说这样比较清楚
    private void setListeners(){
        Onclick onClick=new Onclick();
        mbtnTextView.setOnClickListener(onClick);
        mbtnButton.setOnClickListener(onClick);
        mbtnEditText.setOnClickListener(onClick);
        mbtnRadioButton.setOnClickListener(onClick);
    }

    public class Onclick implements View.OnClickListener{

        @Override
        public void onClick(View view) {
            Intent intent=null;
            switch (view.getId()){
                case R.id.btn_textview:
                    intent=new Intent(MainActivity.this,TextViewActivity.class);
                    break;
                case R.id.btn_button:
                    intent=new Intent(MainActivity.this,ButtonActivity3.class);
                    break;
                case R.id.btn_edittext:
                    intent=new Intent(MainActivity.this,EditTextActivity.class);
                    break;
                case R.id.btn_radioButton:
                    intent=new Intent(MainActivity.this,RadioButtonActivity.class);
                    break;
            }
            startActivity(intent);
        }
    }
}