2. 클릭하면 name 입력값 나오는 코딩.

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private Button mybutton;            // object define
    private TextView showText;
    private EditText enterName;                 //      V

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

        mybutton = findViewById(R.id.button);           // interface with xml //id : xml의 각 id 동일
        enterName = findViewById(R.id.editText);        //instantiate           V

        mybutton.setOnClickListener(new View.OnClickListener() {        // on click하면 나올동작 설정.   V
           @Override
           public void onClick(View view) {

               String name = enterName.getText().toString(); // getter 값 string으로 확실하게   V

               showText.setText("하하하 " + name);     //    V

           }
        });

        showText = findViewById(R.id.textView2);        // id : xml의 각 id 동일


    }
}