If you write a function, then it will be a purple block (method).
Usage:
@SimpleFunction(description = "Block description") public void BlockName(parameters) { /* Your code here. */ }
Example:
@SimpleFunction(description = "Join two text.") public String Join(String t1, String t2) { return t1 + t2; }
And this is for the property, green block.
Get:
@SimpleProperty(category = PropertyCategory.BEHAVIOR, description = "Block description.") public String Source() { return fileName; }
Set:
@DesignerProperty(editorType = PropertyTypeConstants.PROPERTY_TYPE_STRING, defaultValue = "") @SimpleProperty public void Source(String fileName) { this.fileName = fileName; }
This is only example, you need to do research to learn more about AI2 Extensions.