Java 创建对象时找不到源
我想让GolferDBManager类中的一个方法返回我正在从SQLLite数据库构造的对象数组。当我尝试构建数组时,我在方法中得到一个Source Not Found错误Java 创建对象时找不到源,java,android,Java,Android,我想让GolferDBManager类中的一个方法返回我正在从SQLLite数据库构造的对象数组。当我尝试构建数组时,我在方法中得到一个Source Not Found错误 public Golfer[] retrieveGolfers(){ String[] columns = new String[]{"golfer_name", "golfer_init", "usga_index"}; Cursor cursor = db.query(true, DB_TABLE
public Golfer[] retrieveGolfers(){
String[] columns = new String[]{"golfer_name", "golfer_init", "usga_index"};
Cursor cursor = db.query(true, DB_TABLE, columns, null, null, null, null, null, null, null);
cursor.moveToFirst();
int i = 0;
while (cursor.isAfterLast() == false) {
Golfer tGolfer = new Golfer(cursor.getString(0), cursor.getString(1), cursor.getFloat(2));
lGolfers[i] = new Golfer(cursor.getString(0), cursor.getString(1), cursor.getFloat(2));
cursor.moveToNext();
}
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
return lGolfers;
}
lGolfers在上面的类定义中定义为:
public class GolferDBManager {
public static final String DB_NAME = "golfgames";
public static final String DB_TABLE = "golfers";
public static final int DB_VERSION = 1;
private static final String CREATE_TABLE = "CREATE TABLE " + DB_TABLE + " (index INTEGER PRIMARY KEY, golfer_name TEXT, golfer_init TEXT, usga_index DOUBLE);";
private SQLHelper helper;
private SQLiteDatabase db;
private Context context;
private Golfer lGolfers[];
这条线很好用。我添加它是为了调试。下一行生成“未找到源”错误。我知道Golfer类的构造函数在那里,因为我在前一行中使用过
下面是调用所有这些的代码:
public class ReadGolfers extends Activity {
public Golfer Golfers[];
private GolferDBManager mydManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_read_golfers);
mydManager = new GolferDBManager(this);
mydManager.openReadable();
Golfers = mydManager.retrieveGolfers();
mydManager.retrieveGolfers();
mydManager.close();
}
}
有人能帮我理解为什么这不起作用吗
谢谢
事后,我更改了方法,将对象数组传递给它,如下所示:
public void retrieveGolfers(Golfer lgolfers[]){
String[] columns = new String[]{"golfer_name", "golfer_init", "usga_index"};
Cursor cursor = db.query(true, DB_TABLE, columns, null, null, null, null, null, null, null);
cursor.moveToFirst();
int i = 0;
while (cursor.isAfterLast() == false) {
lgolfers[i] = new Golfer(cursor.getString(0), cursor.getString(1), cursor.getFloat(2));
cursor.moveToNext();
}
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
}
还是没有乐趣。事实上这整句话都错了:
private Golfer lGolfers[];
应该是:
private Golfer[] lGolfers;
并初始化为:
lGolfers = new Golfer[100];
(或您想要的任何尺寸)
更好的方法是使用ArrayList:
private ArrayList<Golfer> lGolfers = new ArrayList<Golfer>();
private ArrayList lGolfers=new ArrayList();
在哪里初始化lGolfers[]数组?它在GolferDBManager类的定义中。这是声明。你在哪里做“新”的东西来实例化它呢?就在这一行,上面写着:lGolfers[i]=newgolfer(cursor.getString(0),cursor.getString(1),cursor.getFloat(2));在调用之前,我还尝试在调用例程(Golfers=null)中实例化它。没有区别。
private ArrayList<Golfer> lGolfers = new ArrayList<Golfer>();