java - 强制类的静态部分在没有实例化的情况下运行

Question

我有一个类:

public class TextViewAttachedProperties {
    public static final String NAMESPACE = "http://schemas.android.com/apk/lib/com.zworks.mvvmandroid";

    private static final Handler uiHandler = new Handler(Looper.getMainLooper());

    private static final String DATA_CONTEXT = "DataContext";
    private static final String TEXT = "Text";

    private static final Listener<PropertyChangedEventArgs<String>> textChanged = new Listener<PropertyChangedEventArgs<String>>() {

        @Override
        public void onEvent(final PropertyChangedEventArgs<String> args) {
            final TextView element = (TextView) args.getSource();

            if (element != null && args.getNewValue() != null)
                uiHandler.post(new Runnable() {

                    @Override
                    public void run() {
                        element.setText(args.getNewValue());
                    }
                });
        }
    };

    // This two statements have side effects I'm counting on to execute
    private static final AttachedProperty<Object> dataContext = AttachedProperty
        .newProperty(DATA_CONTEXT, NAMESPACE, TextView.class, null); 
    private static final AttachedProperty<String> text = AttachedProperty
        .newProperty(TEXT, NAMESPACE, TextView.class, "", textChanged);
}

问题是它只有在我实例化该类时才会运行。

无论如何我怎样才能强制它运行？

Answer 1

使用

Class.forName("TextViewAttachedProperties");

javadoc州

Returns the Class object associated with the class or interface with the given string name. Invoking this method is equivalent to:

Class.forName(className, true, currentLoader)

where currentLoader denotes the defining class loader of the current class.

其中 true 指定

initialize - whether the class must be initialized

当类被初始化时，static 初始化器将被执行，static 字段将被初始化。

还有其他方法可以初始化类型，例如访问类型的 static 非常量变量、调用类的 static 方法或实例化类. They are all在 Java 语言规范中描述。 More or less.