我可以给你一些如何编译的提示，但我怀疑你在任何情况下都走错了方向。即使您的代码编译（并运行）了，它也可能不会做您认为它会做的事情。然而，就目前而言，只是编译方面的变化：

public Class<? extends Something> getSomeClass() {
    return SomethingSpecific.class;
}
public void convertToGenericsAndAssign() {
    Class<? extends Something> str = getSomeClass();
    // you are getting a class object. You need to actually store a class to make it work.
    passString(str);
}
public <D extends Something> void passString(Class<D> strType) {
    // ....;
}
public static class Something {}
public static class SomethingSpecific extends Something {}

我把字体改成 String （不可扩展）到 Something .
正如您在示例中看到的，问题是，您实际上得到了一个 Class 方法中的对象。我不太清楚你为什么期望一个实际对象的示例。如果要示例化该类的对象，则以下代码可能会有所帮助：

public Class<? extends Something> getSomeClass() {
    return SomethingSpecific.class;
}
public void convertToGenericsAndAssign() {
    Class<? extends Something> someClass = getSomeClass();
    // try to get an parameter free constructor:
    try {
        Constructor<? extends Something> constructor = someClass.getConstructor();
        Something instance = constructor.newInstance();
        // Be aware, that the generic type `D` i smore or less just `Something`,
        // because the compiler cannot know at compile time, what subclass of `Something`
        // D should actually be. So it can just induce `Something`.
        passSomething(instance);
    } catch (NoSuchMethodException e) {
        // Handle , if the class does not have an empty constructor.
        e.printStackTrace();
    } catch (SecurityException e) {
        // Handle, if the constructor is not accessible, or if the
        // VM does not allow reflection.
        e.printStackTrace();
    } catch (InstantiationException e) {
        // Handle, if the instance failed to be created.
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // Handle, if the metohd is e.g. private or something.
        e.printStackTrace();
    } catch (IllegalArgumentException e) {
        // This should not be thrown, as you pass no arguments, but
        // you still have to catch it.
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        // If the constructor threw an internal exception.
        e.printStackTrace();
    }
}
public <D extends Something> void passSomething(D strType) {
    // ....;
}
public static class Something {}
public static class SomethingSpecific extends Something {}