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Introduction. What is SwissKnife?

SwissKnife is a multi-purpose library based -only in behavior, not in code- on other libraries such as ButterKnife or AndroidAnnotations.

A Swiss army Knife is like a Dagger, but although it may be less sharp, it can be more handy 😉.

This library is only compatible with Groovy language as it uses its Ast processing to generate the final code. If you don't use Groovy on your Android projects yet, you can find some info about how to use it here.

Don't be afraid of using Groovy, Android Studio supports it really well, its syntax is almost the same as Java's, it's compatible with Dalvik and ART and can be mixed with your existing Java code. Also, most times turning a Java class into a Groovy one is as easy as changing the file extension from .java to .groovy.

How to use the annotations

SwissKnife is heavily based on annotations. Most annotations will need only one parameter named value which can be a View id or a list of ids. When it's the only annotation parameter, the "value=" part can be ignored.

@InjectView(R.id.button)
Button myButton;

@InjectView(value=R.id.button)
Button myButton;

// To inject several views, the annotation is @InjectViews, in plural
@InjectViews([R.id.view_1, R.id.view_2])
List<View> myViews;

// This case here is special. If the name of the field is the same as the id, the @InjectView annotation doesn't need any parameters
@InjectView()
Button button_1;

Also, you can have several listener injection methods. When the listener is triggered on the provided view, they will execute the code specified in the method. On some annotations, a "method" parameter is also required to specify which method of the listener interface will be triggered.

@OnClick(R.id.button)
public void onClick() {
    Toast.makeText(this, "Button clicked", Toast.LENGTH_SHORT).show();
}

@OnItemSelected(value=R.id.list, method="OnItemSelected.Method.NOTHING_SELECTED")
public void onItemSelected(AdapterView adapterView) {
    Toast.makeText(this, "Nothing selected", Toast.LENGTH_SHORT).show();
}

Also, you can't just use any combination of parameters you want on the method. Each annotation has its compatible method declarations. You can see more in each annotation's wiki page.