样式化在Android上以编程方式创建的视图

Question

So guys I was reading that it's simply not possible to set the style of a view via Java. There is no such method myView.setStyle("styleName") yet.

Then when you create your layout elements by code, such as textvews , and imageviews or linearlayouts as containers, how do you set their style? Do you assign rule by rule of each newly created element? Or is there a more efficient way to do this task?

@EDIT

Alright, I figured out how do it. Will answer my question with the solution I'm using

Answer 1

Each View or its subclass has a third constructor that take the Style argument. For example, this constructor of View. Mention the Style resource id for this view and thus it should be mentioned during view creation.

From documentation

The default style to apply to this view. If 0, no style will be applied (beyond what is included in the theme). This may either be an attribute resource, whose value will be retrieved from the current theme, or an explicit style resource.

Answer 2

You can subclass the view you want to style and pass the style you wish to apply during runtime. Something like the below class which simply sets a custom font to TextView. Mainly, you need to look into the 3rd constructor where you can supply your style.

public class TextViewRoboto extends TextView {

    public TextViewRoboto(Context context) {
        super(context);
    }

    public TextViewRoboto(Context context, AttributeSet attrs) {
        super(context, attrs);
        setCustomFont(context, attrs);
    }

    public TextViewRoboto(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        setCustomFont(context, attrs);
    }

    private void setCustomFont(Context ctx, AttributeSet attrs) {
        setCustomFont(ctx, "roboto-light.ttf");
    }

    public boolean setCustomFont(Context ctx, String asset) {
        Typeface tf = null;
        try {
            tf = Typefaces.get(ctx, asset);
        } catch (Exception e) {
            Logger.e("Could not get typeface: " + e.getMessage());
            return false;
        }

        setTypeface(tf);
        return true;
    }

}

Answer 3

The solution I found The goal is to create elements programmatically that were previously styled somewhere else.

First, I created a new XML file in the res/layout folder. I named it template.xml and inserted the following code in it:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    style="@style/rootElement"
    >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/firstChildId"
        style="@style/firstChild" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        style="@style/secondChild" />

</LinearLayout>

And then I styled then the way I wanted in styles.xml file

<resources xmlns:android="http://schemas.android.com/apk/res/android">
    <style name="rootElement">
        <!-- style -->          
    </style>

    <style name="firstChild">
        <!-- style -->     
    </style>
</resources>

Now, in my Activity class I added:

LinearLayout rootElement = (LinearLayout) getLayoutInflater().inflate(R.layout.template, null);
someOtherView.addView(rootElement);

The inflater will load the template we created in res/layout/template.xml (all the elements in that file and its attributes) and assign it to rootElement that is then used in my code for anything else. Example

TextView firstChild = (TextView) rootElement.getChildAt(0);
firstChild.setText("It is the firstChild element");

or

TextView firstChild = (TextView) rootElement.findViewById(R.id.firstChildId);
...

Quite easy, isn't it?! I hope that helps

Answer 4

You can use themes and styles

A theme can be applied to the whole application by specifying the name of the theme in the Android manifest

eg <application android:theme="@style/CustomTheme">

You can override the theme for a specific activity by specifying a specific style.

There are various predefined themes Holo Light and Holo Dark are the more common themes. Most apps start by creating a new theme that is inherited from one of the above themes and overriding specific elements as needed.

The best thing to do really is to refer to the documentation, which should always be your first port of call.

http://developer.android.com/guide/topics/ui/themes.html