Verschachtelte Klassen und Verwandtes

package my.scribble2021q4a;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

public class EnclosingClass {
    private String[] tokens = { "fff", "u", "bbb", "bb", "zzzz", "zz", "ff", "aaaa", "a" };

    public EnclosingClass() {
        System.out.println("now in constructor for object of DemoNestingOuterClasses ...");
    }

    public static void main(String[] args) {
        EnclosingClass dnocObj = new EnclosingClass();
        dnocObj.someMethod();
        //
        System.out.println("----- static nested classes -----");
        StaticNestedClass dnocSncObj1 = new StaticNestedClass("dnocSncObj1"); // shorter, ok within nesting class
        //From another class use EnclosingClass.StaticNestedClass
        //
        System.out.println("----- (ordinary) inner classes -----");
        InnerClass icObj1 = dnocObj.new InnerClass("icObj1");

        System.out.println("----- Method containing local classes -----");
        dnocObj.methodWithLocalClass();
        dnocObj.methodWithLambda();
    }

    public void someMethod() {
        System.out.println("now in someMethod() ...");
    }

    public /* important--> */ static /* <-- */ class StaticNestedClass {  // used in main(..)

        private String title;

        public StaticNestedClass(String title) {
            System.out.format("now in constructor of StaticNestedClass-object '%s' ...%n", title);
        }
    }

    public class InnerClass {  // used in main(..)
        public InnerClass(String title) {
            System.out.format("now in constructor of InnerClass-object '%s' ...%n", title);
        }
    }

    public void methodWithLocalClass() {
        System.out.println("now in method 'methodWithLocalClass()'");

        class LocalClass {   // Start Implementation
            public LocalClass() {
                System.out.println("now in constructor of 'LocalClass'");
            }

            public void demoMethod1() {
                System.out.println("now in method 'LocalClass#demoMethod1()'");
            }
        }  // End Implementation

        LocalClass lcObj1 = new LocalClass();  // Instantiate LocalClass
        lcObj1.demoMethod1();  // use object of LocalClass (ALL WITHIN this single method!)
    }

    public void methodWithAnonymousInnerClass() {
        System.out.println("now in method 'methodWithAnonymousInnerClass()'");

        List<String> names = new ArrayList<>(Arrays.asList(tokens));

        names.sort(  // Start AnonymousInnerClass
                new Comparator<String>() {   // can extend class or implement interface

                    @Override
                    public int compare(String s1, String s2) {
                        int cmp = s1.length() - s2.length();  // first by length
                        if (cmp == 0) {
                            cmp = s1.compareTo(s2);   // if same length: by ordinary string-compare
                        }
                        return cmp;
                    }
                }  // End AnonymousInnerClass
        );
        // the single param object is directly created with the 'new' before the implementation!
    }

    public void methodWithLambda() {
        System.out.println("now in method 'methodWithLambda()'");

        List<String> names = new ArrayList<>(Arrays.asList(tokens));
        System.out.println("unsorted list: " + names);
        names.sort(  // Start LambdaExpression
                (s1, s2) -> {
                    int cmp = s1.length() - s2.length();  // first by length
                    if (cmp == 0) {
                        cmp = s1.compareTo(s2);   // if same length: by ordinary string-compare
                    }
                    return cmp;
                }  // End LambdaExpression
        );
        System.out.println("list sorted (length, then alphabetical): " + names);
    }

    //TODO: Method reference example
}