var File = Java.type("java.io.File"); var f = new File['(String,String)'](); results in x.js:2 TypeError: Java method [jdk.internal.dynalink.beans.SimpleDynamicMethod File java.io.File.java.io.File(String,String)] cannot be used as a constructor. Actually, it is a constructor - just that number of actual arguments do not match signature. Similar issue with explicit constructor selection via Native java package as well: var Color = java.awt["Color(int,int,int)"] var c = new Color(255, 255) t.js:2 TypeError: Java method [jdk.internal.dynalink.beans.SimpleDynamicMethod Color java.awt.Color.java.awt.Color(int,int,int)] cannot be used as a constructor.