1-27安卓自学

  今天解决昨天的问题，按照网上的例子没有实现，发现是变量的名称没有修改正确，因此，接下来要做的就是从数据库读取出内容然后放在一个HashMap中，然后根据固定的代码格式取值显示就行，代码如下：

public class XIANSHI extends AppCompatActivity {
    private DataBase databaseHelper;   //用于创建帮助器对象
    private SQLiteDatabase db;   //用于创建数据库对象
    private static final String name = "JZ.db"; //数据库名称
    private static final int version = 1; //数据库版本

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_x_i_a_n_s_h_i);
        ListView listView = (ListView) this.findViewById(R.id.listView);
        List<Bean> list = new ArrayList<Bean>();
        databaseHelper = new DataBase(this, name, null, version);
        DataBase moh = new DataBase(this, "JZ.db", null, 1);
        SQLiteDatabase db = moh.getReadableDatabase(); // 以只读的方式打开数据库
        String sql = "select * from ben ;";
        Cursor cursor = db.rawQuery(sql, null);
        while (cursor.moveToNext()) {

            String date = cursor.getString(cursor.getColumnIndex("date"));
            String leixing = cursor.getString(cursor.getColumnIndex("leixing"));
            String num = cursor.getString(cursor.getColumnIndex("num"));
            String yuanyin = cursor.getString(cursor.getColumnIndex("yuanyin"));
            Bean JL = new Bean(date, leixing, num, yuanyin);
            list.add(JL); // 添加到数组
        }

        List<HashMap<String, Object>> Item = new ArrayList<>();
        for (int i = 0; i < list.size(); i++) {
            HashMap<String, Object> item = new HashMap<>();
            item.put("RQ", list.get(i).getDate());
            item.put("LX", list.get(i).getLeixing());
            item.put("SUM", list.get(i).getNum());
            item.put("YY", list.get(i).getYuanyin());
            Item.add(item);
        }
        SimpleAdapter adapter = new SimpleAdapter(XIANSHI.this, Item, R.layout.item, new String[]{"RQ", "LX", "SUM", "YY"}, new int[]{R.id.RQ, R.id.LX, R.id.SUM, R.id.YY});
        listView.setAdapter(adapter);
    }

}