ObjectTest.java

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package com.blogspot.howdoidothatinjava.tutorials;   import java.util.ArrayList; import java.util.Collection; import java.util.List; import java.util.function.Consumer; import java.util.function.Function; import java.util.function.Predicate; import java.util.stream.Collectors;   import com.blogspot.howdoidothatinjava.sandbox.TestObject;   public class ObjectTest {           private final static String under = "*";           public static void main(String[] args) {                   List<TestObject> objList = TestObject.generateTestObjectList();                   println("Objects in the list:", under);         println();                   for (TestObject t: objList){             t.displayObject();         }                   println();                   //Ex. 1 - Hardcoded Result         println("Ex. 1: Hardcoded Result", under);         println();         println("TestObject with a > 20 (hardcoded)");         println();         printObjectsWithAGreaterThanTwenty(objList);         println();                   //Ex. 2 - Parameterized Range         println("Ex. 2 - Parameterized Range", under);         println();         println("TestObject with b between 10 and 70 inclusive");         println();         printObjectsWithBInRange(objList, 10, 70, Inclusivity.BOTH);         println();                   //Ex. 3 - Use of Local Class         println("Ex. 3 - Use of Local Class", under);         println();         println("TestObject with starting with 'S' and a*3 <= b");         println();                   class TestObjectForNameAndRange implements TestObjectValidator {               public boolean test(TestObject t) {                 return t.getName().startsWith("S") && t.getA() * 3 <= t.getB();             }         }                   printTestObjects(objList, new TestObjectForNameAndRange());         println();                   //Ex. 4 - Use of Anonymous Class         println("Ex. 4 - Use of Anonymous Class", under);         println();         println("TestObject with starting with 'S' and a*3 <= b");         println();                   printTestObjects(objList, new TestObjectValidator() {                           public boolean test(TestObject t) {                 return t.getName().startsWith("S") && t.getA() * 3 <= t.getB();             }         });         println();                   //Ex. 5 - Use of Lambda         println("Ex. 5 - Use of Lambda", under);         println();         println("TestObject with starting with 'S' and a*3 <= b");         println();                   printTestObjects(objList, (TestObject t)->t.getName().startsWith("S") && t.getA() * 3 <= t.getB());         println();                   //Ex. 6 - Use of Predicate in place of Lambda         println("Ex. 6 - Use of Predicate in place of Lambda", under);         println();         println("TestObject with name containing 's', case insensitive");         println();         printTestObjectsWithPredicate(objList, t -> t.getName().toLowerCase().contains("s"));         println();                   //Ex. 7 - Use of Predicate and Consumer Lambda         println("Ex. 7 - Use of Predicate and Consumer Lambda", under);         println();         println("TestObject with name ending in 'y', case insensitive");         println();         printTestObjectWithPredicateAndConsumer(objList, t -> t.getName().toLowerCase().endsWith("y"), t -> t.displayObject());         println();                   //Ex. 8 - Use of Predicate, Function and Consumer         println("Ex. 8 - Use of Predicate, Function and Consumer", under);         println();         println("TestObject name where a >= b");         println();         printTestObjectWithPredicateFunctionAndConsumer(objList, t->t.getA() >= t.getB(), t -> t.getName(), name -> println(name));         println();                   //Ex. 9 - Use of Generics To Add Further Flexibility         println("Ex. 9 - Use of Generics To Add Further Flexibility", under);         println();         println("TestObject name where a < b");         println();         processObjects(objList, t -> t.getA() < t.getB(), t -> t.getName(), name -> println("TestOblject (" + name + ")"));         println();                   //Ex. 10 - Use of Generics to Process Objects and Return Result Collection         println("Ex. 10 - Use of Generics to Process Objects and Return Result Collection", under);         println();         println("TestObject count of names matched where a < b");         println();         List<String> results = processObjects(objList, t -> t.getA() < t.getB(), t -> t.getName());         println("The number of results in List returned was " + results.size());         println();                   //Ex. 11 - Use of Bulk Data Methods to Repeat Results in Ex. 10         println("Ex. 11 - Use of Bulk Data Methods to Repeat Results in Ex. 10", under);         println();         println("TestObject count of names matched where a < b");         println();         results.clear();         results = objList.stream().filter(t -> t.getA() < t.getB()).map(t -> t.getName()).collect(Collectors.toList());         println("The number of results in List returned was " + results.size());         println();                   //Ex. 12 - Use of Bulk Data Method Without Temporary Collection         println("Ex. 12 - Use of Bulk Data Method Without Temporary Collection", under);         println();         println("TestObject count of predicate results to achieve same result as in Ex. 10 & Ex. 11");         println();         println("The number of results found in filter was: " + objList.stream().filter(t-> t.getA() < t.getB()).count());         println();                   //Rx. 13 - Use of Named Predicates as Variables         println("Rx. 13 - Use of Named Predicates as Variables", under);         println();         println("Use of named Predicate to get range where b > 10 and b < 35");         println();         Predicate<TestObject> p1 = t -> t.getB() > 10 && t.getB() < 35;         processGenericObjects(objList, p1, t -> t.displayObject());         println();         println("Use of second named predicate to find names containing 'er'");         println();         Predicate<TestObject> p2 = t -> t.getName().toLowerCase().contains("er");         processGenericObjects(objList, p2, t -> println("TestObject (" + t.getName() + ")"));         println();                   //Ex. 14 - Use of Named Consumer to Customize Print Formatting         println("Ex. 14 - Use of Named Consumer to Customize Print Formatting", under);         println();         println("Print TestObjects where name contains 'a' using named Consumer using TestObject's displayObject()");         println();         Consumer<TestObject> printStandard = t -> t.displayObject();         processGenericObjects(objList, t -> t.getName().toLowerCase().contains("a"), printStandard);         println();         println("Print TestObjects where name contains 'a' using named Consumer using different print function");         println();         Consumer<TestObject> otherPrintFormat = t -> displayOtherFormat(t);         processGenericObjects(objList, t -> t.getName().toLowerCase().contains("a"), otherPrintFormat);                         }       private static void printObjectsWithAGreaterThanTwenty(List<TestObject> list) {         // get each element in the colection and display it based on criteria         for(TestObject t : list){             if (t.getA() > 20) t.displayObject();         }     }           private static void printObjectsWithBInRange(List<TestObject> list, int low, int high, Inclusivity rule) {         for(TestObject t : list){             switch (rule){                 case BOTH:                     if(t.getB() >= low && t.getB() <= high) t.displayObject();                     break;                 case END:                     if(t.getB() > low && t.getB() <= high) t.displayObject();                     break;                 case START:                     if(t.getB() >= low && t.getB() < high) t.displayObject();                     break;                 case NONE:                     if(t.getB() > low && t.getB() < high) t.displayObject();             }         }     }           private static void printTestObjects(List<TestObject> list, TestObjectValidator validator){         for(TestObject t : list){             if (validator.test(t)) t.displayObject();         }     }           private static void printTestObjectsWithPredicate(List<TestObject> list, Predicate<TestObject> filter){         for(TestObject t : list){             if(filter.test(t)) t.displayObject();         }     }           private static void printTestObjectWithPredicateAndConsumer(List<TestObject> list, Predicate<TestObject> filter, Consumer<TestObject> voidFunction) {         for (TestObject t : list){             if(filter.test(t)) voidFunction.accept(t);         }               }           private static void printTestObjectWithPredicateFunctionAndConsumer(List<TestObject> list,             Predicate<TestObject> filter, Function<TestObject,String> mapper, Consumer<String> voidFunction){         for (TestObject t : list){             if(filter.test(t)) {                 String out = mapper.apply(t);                 voidFunction.accept(out);             }         }     }           private static <T, U> void processObjects(Iterable<T> collection, Predicate<T> filter, Function<T, U> mapper, Consumer<U> voidFunction){         for(T t : collection){             if(filter.test(t)){                 U u = mapper.apply(t);                 voidFunction.accept(u);             }         }     }           private static <T, U> List<U> processObjects(Iterable<T> collection, Predicate<T> filter, Function<T,U> mapper){         List<U> uList = new ArrayList<U>();         for(T t : collection){             if (filter.test(t)){                 uList.add(mapper.apply(t));             }         }         return uList;     }           private static <T> void processGenericObjects(Collection<T> collection, Predicate<T> criteria, Consumer<T> voidFunction){         collection.stream().filter(criteria).forEach(voidFunction);     }           private static void displayOtherFormat(TestObject t){         println("\tTestObject (" + t.getName() + ")");         println("\t\ta: " + t.getA());         println("\t\tb: " + t.getB());         println();     }           // Functional Interfaces     interface TestObjectValidator {         boolean test(TestObject t);     }       // Methods out of pure laziness     private static void println(){         println(null);     }           private static void println(String out){         println(out, null);     }           private static void println(String out, String under){         if (null == out) {             System.out.println();         } else {             System.out.println(out);             if(null != under && !under.isEmpty()){                 StringBuffer sb = new StringBuffer();                 while (out.length() > 0){                     sb.append(under);                     out = out.substring(1);                 }                 System.out.println(sb.toString());             }         }     }      private enum Inclusivity {          START, END, BOTH, NONE      } }