动态传递布局 ID

发布于 2024-12-02 11:44:54 字数 1919 浏览 4 评论 0原文

我想实现一个“最喜欢的列表”，假设我有一个空布局。在onCreate()处有super.onCreate(savedInstanceState); setContentView(R.layout.main); 然后我打开一个包含我最喜欢的动物的数据库，加载一些内容并向布局添加动态按钮。

数据库架构是这样的：
CREATE TABLE Animals(_id INTEGER PRIMARY KEY, name TEXT NOT NULL,layout TEXT NOT NULL)

数据库中有：

_id - - - - - - - - name - - - - - - - - - 布局 1 - - - - - - - - -- cat - - - - - - - - -- R.layout.cat 2 - - - - - - - - -- 狗 - - - - - - - - -- R.layout.dog 3 - - - - - - - - -- 海龟 - - - - - - - - R.layout.turtle

当然是layout/xml-files (R.layout.cat, R.layout .dog、R.layout.turtle) 存在。

然后你会看到三个按钮，分别写着“猫”、“狗”和“乌龟”。在OnClickListener 中，有以下内容：

    Intent intent = new Intent(MyFavorites.this, Animal.class);  
    Log.d ("onClick", button.getmyLayout());  
    // Shows either R.layout.cat, R.layout.dog or R.layout.turtle 
    // depending on what button was pressed. This works fine.
    intent.putExtra("myLayout", button.getmyLayout());    
    // closes the database
    myDbHelper.close();
    startActivity(intent);

Animal.class 可以显示所有的animal-xml-文件，因为它们都具有相同的功能。这就是为什么布局总是传递给同一个类的原因！

Animal.class：

    @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            final int myLayout = getIntent().getIntExtra("myLayout", R.layout.main);
            setContentView(myLayout);
        }

现在问题来了。我传递一个字符串而不是一个整数，在日志猫中有：

键 myLayout 需要整数，但值是 java.lang.String。返回默认值2130903044。

默认值是 R.layout.main，您可以在自动生成的 R.class 中找到它，它是十六进制数，十进制数是 2130903044。所以我确实理解错误消息。但我想不出另一种方法来解决这个问题。我正在考虑 R.class 中的 getters 和 setters，但当然它们会在下一个构建时被删除。

原文

I want to implement a 'favorite list' and let's assume that I have got an empty layout. At onCreate() there is super.onCreate(savedInstanceState); setContentView(R.layout.main); and then I open a database with my favorite animals, load a few things and add dynamically buttons to the layout.

The database schema is this:

CREATE TABLE animals(_id INTEGER PRIMARY KEY, name TEXT NOT NULL, layout TEXT NOT NULL)

and in the database there is:

_id - - - - - - - - name - - - - - - - - - layout 1 - - - - - - - - -- cat - - - - - - - - -- R.layout.cat 2 - - - - - - - - -- dog - - - - - - - - -- R.layout.dog 3 - - - - - - - - -- turtle - - - - - - - - R.layout.turtle

Of course the layouts/xml-files (R.layout.cat, R.layout.dog, R.layout.turtle) exist.

So then you see three buttons saying cat, dog and turtle. In the OnClickListener there is the following:

    Intent intent = new Intent(MyFavorites.this, Animal.class);  
    Log.d ("onClick", button.getmyLayout());  
    // Shows either R.layout.cat, R.layout.dog or R.layout.turtle 
    // depending on what button was pressed. This works fine.
    intent.putExtra("myLayout", button.getmyLayout());    
    // closes the database
    myDbHelper.close();
    startActivity(intent);

The Animal.classcan show all animal-xml-files because they all have the same functionality. This is why the layout is always passed on to the same class!

The Animal.class:

    @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            final int myLayout = getIntent().getIntExtra("myLayout", R.layout.main);
            setContentView(myLayout);
        }

Now here is the problem. I pass on a String and not an Integer and in the log cat there is:

Key myLayout expected Integer but value was a java.lang.String. The default value 2130903044 was returned.

The default value is R.layout.main which you find in the autogenerated R.class as a hex number and in decimal it is 2130903044. So I do understand the error message. But I cannot think of another way to solve this problem. I was thinking about getters and setters in the R.class but of course they will be deleted at the next build.

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哑 2024-12-09 11:44:54

请参阅这个问题，我认为这就是您所需要的。基本上你可以通过使用字符串来获取资源...

int i = this.getResources().getIdentifier("cat", "layout", this.getPackageName());

并且这里是 getIdentifier() 的文档。

Please see this question, I think it is what you need. Basically you can get the resource by using a string ...

int i = this.getResources().getIdentifier("cat", "layout", this.getPackageName());

And here is the documentation for getIdentifier().

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你是我的挚爱i 2024-12-09 11:44:54

如果您的布局数量有限且合理（您定义合理的％），我建议使用
只是静态映射：

static Map<String,Integer> layouts = new HashMap<String,Integer>()
static {
   layouts.put("cat",R.layout.cat);
   ...
   layouts.put("unicorn",R.layout.unicorn);
}

这样您将获得编译时安全性，并且在运行时会更快。

If your amount of layouts is finite and reasonable (you define reasonable %) I would propose to use
just static map:

static Map<String,Integer> layouts = new HashMap<String,Integer>()
static {
   layouts.put("cat",R.layout.cat);
   ...
   layouts.put("unicorn",R.layout.unicorn);
}

This way you will get compile time safety, and it would be faster at the runtime.

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~没有更多了~