Java 字符串与 BaseColumns._ID 连接会带来错误
在 Eclipse 中，当我输入以下内容时：
BaseColumns._ID, + "=?"
我得到：
The operator + is undefined for the argument type(s) String
这怎么可能，它们都是字符串，不是吗？
现在这里是 BaseColumns._ID 的文档：
public static final String _ID
我正在编写的代码是：
public void deteleProfile(Long id) throws SQLException {
SQLiteDatabase db = helper.getWritableDatabase();
Integer i = db.delete(ProlificDatabase.TABLE, BaseColumns._ID, + "=?", new String[] {id.toString()});
Log.d(TAG, i + " records deleted where id is " + id);
In eclipse as soon as i type this out:
BaseColumns._ID, + "=?"
I get:
The operator + is undefined for the argument type(s) String
How is that possible, they are both Strings aren't they?
now here is documentation for BaseColumns._ID:
public static final String _ID
the code I am writing is:
public void deteleProfile(Long id) throws SQLException {
SQLiteDatabase db = helper.getWritableDatabase();
Integer i = db.delete(ProlificDatabase.TABLE, BaseColumns._ID, + "=?", new String[] {id.toString()});
Log.d(TAG, i + " records deleted where id is " + id);
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评论（4）
你有一个流氓逗号：
应该是否则
它会尝试使用
+ "=?"作为独立参数，而+充当 一元运算符。You've got a rogue comma:
should probably be
Otherwise it's trying to use
+ "=?"as a stand-alone argument with the+acting as a unary operator.您的意思是
BaseColumns._ID + "=?"而不是BaseColumns._ID, + "=?"吗？编译器只会将
+运算符的左侧视为空。Do you mean
BaseColumns._ID + "=?"instead ofBaseColumns._ID, + "=?"?The compiler just sees the left hand side of the
+operator as being empty.请参阅 此文档介绍如何使用 db.delete 方法。而不是 BaseColumns._ID，+“=？” - 你应该这样做：
See this documentation on how to use the db.delete method. Instead of BaseColumns._ID, + "=?" - you should be doing this:
可爱的额外
，（逗号）...喜欢逗号的本质，它意味着表达式和痛苦之间的分隔符...当你忽略它们时！Lovely extra
,(comma)... love the commas for what they are, meaning a separator between expressions and a pain ... for when you overlook them!