Android studio 大作业 简单的备忘录

package com.example.notebook.activity; import android.Manifest; import android.content.Intent; import android.content.pm.PackageManager; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.v4.content.ContextCompat; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.KeyEvent; import android.view.LayoutInflater; import android.view.View; import android.widget.Button; import android.widget.Toast; import com.chad.library.adapter.base.BaseQuickAdapter; import com.example.notebook.R; import com.example.notebook.adapter.NotebookAdapter; import com.example.notebook.bean.NotebookBean; import com.example.notebook.db.DBManager; import java.util.ArrayList; import java.util.List; import java.util.Timer; import java.util.TimerTask; public class MainActivity extends AppCompatActivity implements View.OnClickListener { private static final String TAG = MainActivity.class.getSimpleName(); private static final int QR_CODE = 1001; private static final int REQUEST_CODE = 1002; private RecyclerView recyclerView; private Button btnAdd; private List<NotebookBean> mNotebookList; private NotebookAdapter mAdapter; private DBManager mDBManager; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); checkPermission(); initView(); initRecyclerView(); mDBManager = new DBManager(this); getNotebookList(); } /** * 绑定视图VIEW */ private void initView() { recyclerView = findViewById(R.id.recycler_view); btnAdd = findViewById(R.id.btn_add); btnAdd.setOnClickListener(this); } private void initRecyclerView(){ mNotebookList = new ArrayList<>(); mAdapter = new NotebookAdapter(R.layout.item_notebook, mNotebookList); recyclerView.setLayoutManager(new LinearLayoutManager(this)); recyclerView.setAdapter(mAdapter); mAdapter.bindToRecyclerView(recyclerView); mAdapter.setEmptyView(R.layout.view_no_data); mAdapter.setOnItemChildClickListener(new BaseQuickAdapter.OnItemChildClickListener() { @Override public void onItemChildClick(BaseQuickAdapter adapter, View view, int position) { Intent intent = new Intent(MainActivity.this, AddNotebookActivity.class); intent.putExtra("isAdd", false); intent.putExtra("notebook", mNotebookList.get(position)); startActivityForResult(intent, REQUEST_CODE); } }); mAdapter.setOnItemChildLongClickListener(new BaseQuickAdapter.OnItemChildLongClickListener() { @Override public boolean onItemChildLongClick(BaseQuickAdapter adapter, View view, int position) { showDeleteDialog(position, mNotebookList.get(position).getNotebookId()); return true; } }); } private void getNotebookList(){ mNotebookList.clear(); mNotebookList.addAll(mDBManager.selectNotebookList()); mAdapter.notifyDataSetChanged(); } private void showDeleteDialog(final int position, final int notebookId){ View view = LayoutInflater.from(this).inflate(R.layout.dialog_delete_notebook, null, false); AlertDialog.Builder builder = new AlertDialog.Builder(this) .setView(view); final AlertDialog alertDialog = builder.create(); alertDialog.show(); alertDialog.getWindow().setBackgroundDrawableResource(android.R.color.transparent); view.findViewById(R.id.btn_confirm).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { mDBManager.deleteNotebook(notebookId); alertDialog.dismiss(); mNotebookList.remove(position); mAdapter.notifyItemRemoved(position); mAdapter.notifyItemRangeChanged(position, mNotebookList.size() - position); } }); view.findViewById(R.id.btn_cancel).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { alertDialog.dismiss(); } }); } @Override public void onClick(View view) { switch (view.getId()) { case R.id.btn_add:// 点击添加按钮 Intent intent = new Intent(MainActivity.this, AddNotebookActivity.class); intent.putExtra("isAdd", true); startActivityForResult(intent, REQUEST_CODE); break; } } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == REQUEST_CODE && resultCode == RESULT_OK){ getNotebookList(); } } /*************连续点击两次退出应用******************/ // 用来计算返回键的点击间隔时间 private boolean keyPress = true; @Override public boolean onKeyDown(int keyCode, KeyEvent event) { //判断按下的键是否是返回键 if (keyCode == KeyEvent.KEYCODE_BACK) { if (keyPress) { Toast.makeText(MainActivity.this, "再按一次返回键退出记事本", Toast.LENGTH_SHORT).show(); keyPress = false; //使用定时器修改keyPress的值，按下两秒后将keyPress设为true new Timer().schedule(new TimerTask() { @Override public void run() { keyPress = true; } }, 2000); } else { //关闭页面 finish(); } return false; } return super.onKeyDown(keyCode, event); } /************************检查授权相关********************************/ private List<String> requestPermissions; // 申请权限相关 private static String[] permissions = new String[]{ Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE }; private boolean checkPermission() { boolean flag = true; requestPermissions = new ArrayList<>(); if (ContextCompat.checkSelfPermission(this, permissions[0]) == PackageManager.PERMISSION_DENIED) { requestPermissions.add(permissions[0]); flag = false; } if (ContextCompat.checkSelfPermission(this, permissions[1]) == PackageManager.PERMISSION_DENIED) { requestPermissions.add(permissions[1]); flag = false; } return flag; } }