安卓的登录注册以及记事本的增删改查

【核心代码】

 private void queryData() { data.clear(); data.addAll(myDBHelper.query()); adapter.notifyDataSetChanged();
    } private void initEvent() { ivAddBtn.setOnClickListener(new View.OnClickListener() { @Override  public void onClick(View v) { //TODO 跳转到添加,并希望添加完成回来告诉我一声我好更新数据  Intent intent = new Intent(MainActivity.this, RecordActivity.class);
                startActivityForResult(intent, 1);
            }
        }); //长按删除  listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() { @Override  public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
                AlertDialog dialog = new AlertDialog.Builder(MainActivity.this)
                        .setTitle("确认删除吗？")
                        .setPositiveButton("确定", new DialogInterface.OnClickListener() { @Override  public void onClick(DialogInterface dialog, int which) {
                                NotepadBean bean = data.remove(position); myDBHelper.delete(bean.getId()); adapter.notifyDataSetChanged();
                                Toast.makeText(MainActivity.this,"删除成功", Toast.LENGTH_SHORT).show();
                            }
                        }).setNegativeButton("取消",null).create();
                dialog.show(); return true; //返回true代表我已经处理这个事件，否则会和单击事件冲突  }
        }); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override  public void onItemClick(AdapterView<?> parent, View view, int position, long id) { //TODO 跳转到修改数据，因此我们要带参数过去  Intent intent = new Intent(MainActivity.this, RecordActivity.class);
                intent.putExtra("data",data.get(position));
                startActivityForResult(intent, 1);
            }
        });
    } @Override  protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == 1 && resultCode == 2 ) { //添加完成  做数据的更新  queryData();
        }
    } public void logout(View view) {
        SharedPreferences spf = getSharedPreferences("spfRecord", MODE_PRIVATE);
        SharedPreferences.Editor edit = spf.edit();
        edit.putBoolean("isLogin", false);
        edit.apply();
        Intent intent = new Intent(this, LoginActivity.class);
        startActivity(intent); this.finish();
    }
}