网上没有找到合适的案例，最后自己实现 实现原理：在每次往数据库里写入记录时，判断里面的记录数为多少，倘若大于或等于最大记录数，则删除首行记录数 ```java //计算数据库的记录数量 private int getCount() { Cursor cursor = getCursor(); if (cursor != null) { int count = cursor.getCount(); cursor.close(); return count; } return 0; } //根据读取到的第一个主键来删除第一条记录 private void deleteFirst() { Cursor cursor = getCursor(); if (cursor != null) { //把cursor移动到第一条记录 if (cursor.moveToFirst()) { //读出id int id = cursor.getInt(cursor.getColumnIndex("id")); myDB.getWritableDatabase().execSQL("DELETE FROM " + TABLE_NAME + " WHERE id=" + id); } cursor.close(); } } //获取Cursor private Cursor getCursor() { return myDB.getReadableDatabase().query(TABLE_NAME, null, null, null, null, null, null, null); } //保存bean到数据库 public void save(EnvironmentBean bean) { //记录超过20条，先删除第一行 if (getCount() >= 20) deleteFirst(); ContentValues cv = new ContentValues(); myDB.getWritableDatabase().insert(TABLE_NAME, null, cv); } ``` Last modification：March 29th, 2019 at 11:09 am © 允许规范转载 Support If you think my article is useful to you, please feel free to appreciate ×Close Appreciate the author Sweeping payments Pay by AliPay Pay by WeChat
