做音乐软件需求的代码

1.activity的“7”
oncreate
onstart
onstop
onresume
onpause
ondestory
onrestart
2.123切换
package com.example.lenovo.myapplication;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class xiaojie extends AppCompatActivity {
private String TAG =”MAINACTIVITY”;
private Button ABtn;

@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_xiaojie);    Log.e(TAG,"onCreate方法执行...");    ABtn = findViewById(R.id.a_btn);    ABtn.setOnClickListener(new View.OnClickListener(){        @Override        public void onClick(View v){            Intent intent =new Intent(this,xiaosun.class);        }    });}@Overrideprotected void onStart(){    super.onStart();    Log.e(TAG,"onStart方法执行...");}

}
3.上下图片切换