overriding methods and fields for combining and inheriting

The fields and methods in the Blog,scala are the same namespaces, which allows the fields to override the parameterless method. For example, you can change the implementation of contents in the Arrayelement class from one method to a field without modifying the abstract method definition contents in the class element, as an example:

Abstract class Elements {def contents:array[string] val height = contents.length val width = if (height = = 0) 0 else contents (0). Length}

Class Arrayelement (conts:array[string]) extends Elements {//No lazy on the error, now do not understand why, first record the lazy Val Contents:array[stri NG] = Conts}object arrayelement {def main (args:array[string]): Unit = {val array = new Arrayelement (Array ("DD Daaa "," DDDWW ")) println (Array.width)}}

The contents field (defined by Val) in this version of Arrayelement provides a very good implementation for the parameterless method contents (defined with Def) in the element class (in scala2.10.7 version, why should we add lazy before the error? Do not add a null pointer exception!!! ）。

Another way, Scala prohibits defining fields and methods in the same class with the same name. Although Java allows this to be done. example, this will not compile in the Scala class:

Class T2 {private var f = 0 def f = 1//cannot be compiled because the names of fields and methods}

overriding methods and fields for combining and inheriting