<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="4dp">
    <EditText
        android:id="@+id/editTextName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="text"
        android:hint="请输入姓名"/>
    <Button
        android:id="@+id/buttonOk"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="确认"/>
</LinearLayout>

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取按钮
        Button buttonOk=findViewById(R.id.buttonOk);
        //设置按钮点击监听器
        buttonOk.setOnClickListener(new MyOnClickListener());
    }
    //定义按钮点击监听器
    class MyOnClickListener implements View.OnClickListener{
        //按钮点击
        @Override
        public void onClick(View view) {
            if(view.getId()==R.id.buttonOk){//被点击的是确认按钮
                //获取文本框内容
                EditText editTextName=findViewById(R.id.editTextName);
                //显示提示框
                Toast.makeText(MainActivity.this,"欢迎您："+editTextName.getText(),Toast.LENGTH_SHORT).show();
            }
        }
    }
}