黑莓 API / 菜单项
我刚刚学习黑莓 API，试图按照黑莓开发网站上的教程进行操作，但我有点困惑。在界面教程中，他们给出了以下制作菜单项的说明......
private MenuItem _changeCapitol = new MenuItem("Change Capitol", 110, 10)
{
public void run()
{
if (displayed == 0)
_canadaCapitol = _input.getText();
else if (displayed == 1)
_ukCapitol = _input.getText();
else if (displayed == 2)
_usCapitol = _input.getText();
}
};
这一切都很好，现在可以使用。问题是用于创建 MenuItem 的方法已被弃用。所有教程似乎都是针对 4.0 的。我想学习如何以正确的方式执行此操作，因此我查阅了 6.0 API 参考。我尝试将其转换为当前方法，但我无法完全正确。这是我最接近的...
private MenuItem _changecapitol = new MenuItem(new StringProvider("Change Capitol"), 110, 10);
changecapitol.setCommand(new Command(CapitolChange()));
class CapitolChange extends CommandHandler
{
public void execute(ReadOnlyCommandMetadata metadata, Object context)
{
if (displayed == 0)
_canadaCapitol = _input.getText();
else if (displayed == 1)
_ukCapitol = _input.getText();
else if (displayed == 2)
_usCapitol = _input.getText();
}
}
似乎构造函数的括号内确实应该有一些东西，但我无法想象那可能是什么。如果我正确理解了该参考，那么该功能就位于 CommandHandler 内部，所以我认为我的部分是正确的。现在的问题是 Eclipse 在 CapitolChange 构造函数之前抛出一个错误。
changecapitol.setCommand(new Command(CapitolChange()));
我实际上在这条线上遇到了多个错误。一个是错误的构造错误，另一个声称在“setCommand”之后我需要一个“=”。 API 中没有这样的内容，而且在语法上看起来似乎是错误的。我正在调用一个方法而不是赋值。正确的？不？难道我对整件事的看法完全错误吗？
I'm just learning the blackbery API, trying to follow the tutorials on the blackberry dev site, and I am a bit confused. In the interface tutorial they give the following instruction for making menu items...
private MenuItem _changeCapitol = new MenuItem("Change Capitol", 110, 10)
{
public void run()
{
if (displayed == 0)
_canadaCapitol = _input.getText();
else if (displayed == 1)
_ukCapitol = _input.getText();
else if (displayed == 2)
_usCapitol = _input.getText();
}
};
And that's all peachy and works for now. The issue is that the method used to create the MenuItem is deprecated. All of the tutorials appear to be for 4.0. I wanted to learn to do this the proper way so off I went to the 6.0 API Reference. I've tried to convert this to the current method but I can't get it quite right. Here is the closest that I have come...
private MenuItem _changecapitol = new MenuItem(new StringProvider("Change Capitol"), 110, 10);
changecapitol.setCommand(new Command(CapitolChange()));
class CapitolChange extends CommandHandler
{
public void execute(ReadOnlyCommandMetadata metadata, Object context)
{
if (displayed == 0)
_canadaCapitol = _input.getText();
else if (displayed == 1)
_ukCapitol = _input.getText();
else if (displayed == 2)
_usCapitol = _input.getText();
}
}
It seems as if there really should be something inside the brackets on the constructor but I can't imagine what that might be. If I understand the reference properly the functionality goes inside the CommandHandler, so I think I have that part right. The issue right now is that Eclipse is throwing an error on the line before the CapitolChange constructor.
changecapitol.setCommand(new Command(CapitolChange()));
I'm actually getting multiple errors on this line. One is a misplaced construct error, and the other claims that after "setCommand" I need an "=". This is nowhere in the API, and it would seem syntactically wrong. I'm calling a method and not assigning a value. Right? No? Am I just completely wrong on the whole thing?
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评论（2）
您使用了错误的变量，您使用“_changecapitol”创建了 MenuItem 并将其与此changecapitol 一起使用。更正拼写错误并检查错误。
You are using wrong variable, you create MenuItem with "_changecapitol" and using it with this changecapitol. correct the typo and check the errors.
我认为编译错误是由分配命令的位置不当引起的：
因为它被放置在 MenuItem 成员声明之后的类声明部分中的某个位置。
请尝试在其他地方分配命令，也许在屏幕构造函数中。
I think compile error is caused by improper place to have command assigned:
since it is placed somewhere in class declaration part right after MenuItem member declaration.
Please try to assign command elsewhere, maybe in screen constructor.