initial commit

study-annotations-and-reflection-api/.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>study-annotations-and-reflection-api</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

study-annotations-and-reflection-api/src/com/example/lottery/application/LotteryApp.java

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+package com.example.lottery.application;
+
+import com.example.lottery.model.LotteryViewModel;
+import com.example.lottery.service.RandomNumberGeneratorService;
+
+public class LotteryApp {
+
+	public static void main(String[] args) {
+		var lotteryModel = new LotteryViewModel();
+		var service = new RandomNumberGeneratorService();
+		service.generate(lotteryModel);
+		System.out.println(lotteryModel.getNumbers());
+	}
+
+}

study-annotations-and-reflection-api/src/com/example/lottery/model/LotteryViewModel.java

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+package com.example.lottery.model;
+
+import java.util.List;
+
+import com.example.lottery.service.RandomNumber;
+
+public class LotteryViewModel {
+	@RandomNumber(min = 1, max = 60, distinct = true, sorted = true, size = 6)
+	private List<Integer> numbers;
+
+	public List<Integer> getNumbers() {
+		return numbers;
+	}
+
+}

study-annotations-and-reflection-api/src/com/example/lottery/service/RandomNumber.java

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+package com.example.lottery.service;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RandomNumber {
+
+	int min();
+
+	int max();
+
+	boolean distinct();
+
+	boolean sorted();
+
+	int size();
+
+}

study-annotations-and-reflection-api/src/com/example/lottery/service/RandomNumberGeneratorService.java

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+package com.example.lottery.service;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+public class RandomNumberGeneratorService {
+
+	public void generate(Object o) {
+		var clazz = o.getClass();
+		for (var field : clazz.getDeclaredFields()) {
+			if (field.isAnnotationPresent(RandomNumber.class)) {
+				var randomNumberAnnotation = field.getAnnotation(RandomNumber.class);
+				var min = randomNumberAnnotation.min();
+				var max = randomNumberAnnotation.max();
+				var size = randomNumberAnnotation.size();
+				var streamOfNumbers = ThreadLocalRandom.current().ints(min, max);
+				if (randomNumberAnnotation.distinct())
+					streamOfNumbers = streamOfNumbers.distinct();
+
+				streamOfNumbers = streamOfNumbers.limit(size);
+				if (randomNumberAnnotation.sorted())
+					streamOfNumbers = streamOfNumbers.sorted();
+				var numbers = streamOfNumbers.boxed().toList();
+				try {
+					field.setAccessible(true);
+					field.set(o, numbers);
+					field.setAccessible(false);
+				} catch (IllegalArgumentException | IllegalAccessException e) {
+					System.err.println("Error: %s".formatted(e.getMessage()));
+				}
+			}
+		}
+	}
+}

study-interfaces/.classpath

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+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17">
+		<attributes>
+			<attribute name="module" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

study-interfaces/.settings/org.eclipse.core.resources.prefs

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+eclipse.preferences.version=1
+encoding/<project>=UTF-8

study-interfaces/.settings/org.eclipse.jdt.core.prefs

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+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=17
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.release=enabled
+org.eclipse.jdt.core.compiler.source=17

study-utility-classes/.classpath

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+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17">
+		<attributes>
+			<attribute name="module" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

study-utility-classes/.project

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>study-utility-classes</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

study-utility-classes/.settings/org.eclipse.core.resources.prefs

@@ -0,0 +1,2 @@
+eclipse.preferences.version=1
+encoding/<project>=UTF-8

study-utility-classes/.settings/org.eclipse.jdt.core.prefs

@@ -0,0 +1,14 @@
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=17
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.release=enabled
+org.eclipse.jdt.core.compiler.source=17

study-utility-classes/src/com/example/StudyCollation.java

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+package com.example;
+
+import java.text.Collator;
+import java.text.ParseException;
+import java.text.RuleBasedCollator;
+import java.util.ArrayList;
+import java.util.Locale;
+
+public class StudyCollation {
+
+	public static void main(String[] args) throws ParseException {
+		var name1 = "müller";
+		var name2 = "mueller";
+		System.out.println(name1.equals(name2));
+		var names = new ArrayList<String>();
+		names.add("şule");	
+		names.add("şima");	
+		names.add("sema");	
+		names.add("ayşegül");	
+		names.add("zehra");	
+		names.add("ali");	
+		names.add("veli");
+		System.out.println(names);
+		names.sort(String::compareTo);
+		System.out.println(names);
+		// şule == schule
+		System.out.println("şule".equals("schule"));
+		// şima == shema
+		System.out.println("şima".equals("shema"));
+		String basicRules=  "< z < b < c < ç < d < e < f < g < ğ < h "+
+		        "< ı < i < j < k < l < m < n < o < ö < p "+
+		       "< r < s < ş < t < u < ü < v < y < a ";
+		String trExpension= "& şi ; she & ş ; sch & s ; ş & u ; ü & i ; ı " + 
+		                    "& c ; ç & o ; ö & ğ ; g" ;
+		final Collator collator= new RuleBasedCollator(basicRules + trExpension);
+		Collator.getInstance(new Locale("tr","TR"));
+		collator.setStrength(Collator.PRIMARY);
+		System.out.println(collator.equals("şule","schule"));
+		System.out.println(collator.equals("şima","shema"));
+		names.sort(collator::compare);
+		System.out.println(names);
+	}
+
+}

study-utility-classes/src/com/example/StudyDynamicString.java

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+package com.example;
+
+public class StudyDynamicString {
+
+	@SuppressWarnings("unused")
+	public static void main(String[] args) {
+		String name = "jack"; // immutable
+		int result = 42;
+		// StringBuilder: not thread-safe
+		// StringBuffer: thread-safe
+		StringBuffer message = new StringBuffer(388888890);
+		var start = System.currentTimeMillis();
+		for (var i=0;i<50_000_000;++i)
+			message.append(i);
+		var stop = System.currentTimeMillis();
+		System.out.println(message.length());
+		System.err.println("Duration: %d".formatted(stop-start));
+	}
+
+}

study-utility-classes/src/com/example/StudyString.java

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+package com.example;
+
+import java.text.DecimalFormat;
+import java.text.MessageFormat;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.FormatStyle;
+import java.util.Locale;
+import java.util.ResourceBundle;
+
+public class StudyString {
+
+	public static void main(String[] args) {
+		System.setProperty("user.language", "tr"); // ISO2
+		System.setProperty("user.country", "TR");
+		System.getenv().forEach((key,value) -> System.out.println("%s: %s".formatted(key,value)));
+		System.getProperties().forEach((key,value) -> System.out.println("%s: %s".formatted(key,value)));
+		String city = "izmir";
+		Locale tr_TR= new Locale("tr", "TR");
+		System.out.println(city.toUpperCase(tr_TR));
+
+		var now = ZonedDateTime.now();
+		DateTimeFormatter dtf = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.FULL)
+				                                 .withLocale(Locale.GERMAN);
+		System.out.println(dtf.format(now));
+
+		double money = 12_345.67;
+		DecimalFormat df = (DecimalFormat) DecimalFormat.getCurrencyInstance(Locale.CHINA);
+		System.out.println(df.format(money));
+
+		String fullname= "Jack Bauer";
+		var resourceBundle= ResourceBundle.getBundle("messages",Locale.US);
+		var helloTemplate = resourceBundle.getString("hello");
+		var formatter = new MessageFormat(helloTemplate, tr_TR);
+
+		System.out.println(formatter.format(new Object[] {fullname}));
+	}
+
+}

study-utility-classes/src/messages_en_US.properties

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+hello:Hello, {0}!

study-utility-classes/src/messages_tr_TR.properties

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+hello=Merhaba, {0}!