android studio 入门---做一个按键控制程序

程序比hello world复杂一点，主要功能就是按下 第一个按键，该按键颜色会变化，同时右下角edit框文字会有变化

GUI布局是这样的

源代码是这样的：

package com.example.myapplication113;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.graphics.Color;
//import android.widget.TextView;
import android.widget.EditText;
//import android.text;
//import android.content;public class MainActivity extends AppCompatActivity {Button buttonDemo;private EditText  edit1;private EditText  edit2;private int count;@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);buttonDemo=findViewById(R.id.buttonDemo);edit1=findViewById(R.id.editText2);edit2=findViewById(R.id.editText3);//https://www.ixigua.com/6824065263755854339?id=6747622816910148108&logTag=fs8QpcBMA8nG7xKquNxR1buttonDemo.setOnClickListener(new View.OnClickListener(){@Overridepublic void onClick(View v){int cc=count % 3;count++;switch(cc){case 0:buttonDemo.setTextColor(Color.RED );edit1.setText("Red");break;case 1:buttonDemo.setTextColor(Color.GREEN );edit1.setText("Green");break;case 2:buttonDemo.setTextColor(Color.BLUE );edit1.setText("Blue");break;}}});}
}