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iaforek
2017-06-02 00:36:15 +01:00
committed by GitHub
parent 9d0b9dbed1 d3597a84c7
commit a955425592
202 changed files with 6085 additions and 1225 deletions
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core-java/src/main/java/com/baeldung/concurrent/diningphilosophers/DiningPhilosophers.java
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package com.baeldung.concurrent.diningphilosophers;
public class DiningPhilosophers {
public static void main(String[] args) throws Exception {
Philosopher[] philosophers = new Philosopher[5];
Object[] forks = new Object[philosophers.length];
for (int i = 0; i < forks.length; i++) {
forks[i] = new Object();
}
for (int i = 0; i < philosophers.length; i++) {
Object leftFork = forks[i];
Object rightFork = forks[(i + 1) % forks.length];
if (i == philosophers.length - 1) {
philosophers[i] = new Philosopher(rightFork, leftFork); // The last philosopher picks up the right fork first
} else {
philosophers[i] = new Philosopher(leftFork, rightFork);
}
Thread t = new Thread(philosophers[i], "Philosopher " + (i + 1));
t.start();
}
}
}
core-java/src/main/java/com/baeldung/concurrent/diningphilosophers/Philosopher.java
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package com.baeldung.concurrent.diningphilosophers;
public class Philosopher implements Runnable {
private final Object leftFork;
private final Object rightFork;
public Philosopher(Object left, Object right) {
this.leftFork = left;
this.rightFork = right;
}
private void doAction(String action) throws InterruptedException {
System.out.println(Thread.currentThread().getName() + " " + action);
Thread.sleep(((int) (Math.random() * 100)));
}
@Override public void run() {
try {
while (true) {
doAction(System.nanoTime() + ": Thinking"); // thinking
synchronized (leftFork) {
doAction(System.nanoTime() + ": Picked up left fork");
synchronized (rightFork) {
doAction(System.nanoTime() + ": Picked up right fork - eating"); // eating
doAction(System.nanoTime() + ": Put down right fork");
}
doAction(System.nanoTime() + ": Put down left fork. Returning to thinking");
}
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
return;
}
}
}
core-java/src/main/java/com/baeldung/java/enumiteration/DaysOfWeekEnum.java
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package com.baeldung.java.enumiteration;
import java.util.stream.Stream;
public enum DaysOfWeekEnum {
SUNDAY("off"),
MONDAY("working"),
TUESDAY("working"),
WEDNESDAY("working"),
THURSDAY("working"),
FRIDAY("working"),
SATURDAY("off");
private String typeOfDay;
DaysOfWeekEnum(String typeOfDay) {
this.typeOfDay = typeOfDay;
}
public String getTypeOfDay() {
return typeOfDay;
}
public void setTypeOfDay(String typeOfDay) {
this.typeOfDay = typeOfDay;
}
public static Stream<DaysOfWeekEnum> stream() {
return Stream.of(DaysOfWeekEnum.values());
}
}
core-java/src/main/java/com/baeldung/java/enumiteration/EnumIterationExamples.java
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package com.baeldung.java.enumiteration;
import java.util.EnumSet;
public class EnumIterationExamples {
public static void main(String[] args) {
System.out.println("Enum iteration using forEach:");
EnumSet.allOf(DaysOfWeekEnum.class).forEach(day -> System.out.println(day));
System.out.println("Enum iteration using Stream:");
DaysOfWeekEnum.stream().filter(d -> d.getTypeOfDay().equals("off")).forEach(System.out::println);
System.out.println("Enum iteration using for loop:");
for (DaysOfWeekEnum day : DaysOfWeekEnum.values()) {
System.out.println(day);
}
}
}
core-java/src/main/java/com/baeldung/maths/Round.java
+1 -1
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@@ -33,7 +33,7 @@ public class Round {
public static double roundNotPrecise(double value, int places) {
if (places < 0) throw new IllegalArgumentException();
BigDecimal bd = new BigDecimal(value);
bd = bd.setScale(places, RoundingMode.HALF_UP);
return bd.doubleValue();
core-java/src/main/java/com/baeldung/noclassdeffounderror/ClassWithInitErrors.java
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package com.baeldung.noclassdeffounderror;
public class ClassWithInitErrors {
static int data = 1 / 0;
}
core-java/src/main/java/com/baeldung/noclassdeffounderror/NoClassDefFoundErrorExample.java
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package com.baeldung.noclassdeffounderror;
public class NoClassDefFoundErrorExample {
public ClassWithInitErrors getClassWithInitErrors() {
ClassWithInitErrors test;
try {
test = new ClassWithInitErrors();
} catch (Throwable t) {
System.out.println(t);
}
test = new ClassWithInitErrors();
return test;
}
}
core-java/src/main/java/com/baeldung/stream/StreamApi.java
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package com.baeldung.stream;
import java.util.List;
import java.util.stream.Stream;
public class StreamApi {
public String getLastElementUsingReduce(List<String> valueList) {
Stream<String> stream = valueList.stream();
return stream.reduce((first, second) -> second).orElse(null);
}
public Integer getInfiniteStreamLastElementUsingReduce() {
Stream<Integer> stream = Stream.iterate(0, i -> i + 1);
return stream.limit(20).reduce((first, second) -> second).orElse(null);
}
public String getLastElementUsingSkip(List<String> valueList) {
long count = valueList.stream().count();
Stream<String> stream = valueList.stream();
return stream.skip(count - 1).findFirst().orElse(null);
}
}
core-java/src/main/java/com/baeldung/string/StringHelper.java
+5 -5
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@@ -2,23 +2,23 @@ package com.baeldung.string;
import java.util.Optional;
public class StringHelper {
public static String removeLastChar(String s) {
class StringHelper {
static String removeLastChar(String s) {
return (s == null || s.length() == 0) ? s : (s.substring(0, s.length() - 1));
}
public static String removeLastCharRegex(String s) {
static String removeLastCharRegex(String s) {
return (s == null) ? s : s.replaceAll(".$", "");
}
public static String removeLastCharOptional(String s) {
static String removeLastCharOptional(String s) {
return Optional.ofNullable(s)
.filter(str -> str.length() != 0)
.map(str -> str.substring(0, str.length() - 1))
.orElse(s);
}
public static String removeLastCharRegexOptional(String s) {
static String removeLastCharRegexOptional(String s) {
return Optional.ofNullable(s)
.map(str -> str.replaceAll(".$", ""))
.orElse(s);
core-java/src/main/java/com/baeldung/uuid/UUIDGenerator.java
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package com.baeldung.uuid;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.UUID;
public class UUIDGenerator {
/**
* These are predefined UUID for name spaces
*/
private static final String NAMESPACE_DNS = "6ba7b810-9dad-11d1-80b4-00c04fd430c8";
private static final String NAMESPACE_URL = "6ba7b811-9dad-11d1-80b4-00c04fd430c8";
private static final String NAMESPACE_OID = "6ba7b812-9dad-11d1-80b4-00c04fd430c8";
private static final String NAMESPACE_X500 = "6ba7b814-9dad-11d1-80b4-00c04fd430c8";
private static final char[] hexArray = "0123456789ABCDEF".toCharArray();
public static void main(String[] args) {
try {
System.out.println("Type 3 : " + generateType3UUID(NAMESPACE_DNS, "google.com"));
System.out.println("Type 4 : " + generateType4UUID());
System.out.println("Type 5 : " + generateType5UUID(NAMESPACE_URL, "google.com"));
System.out.println("Unique key : " + generateUniqueKeysWithUUIDAndMessageDigest());
} catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
e.printStackTrace();
}
}
/**
* Type 4 UUID Generation
*/
public static UUID generateType4UUID() {
UUID uuid = UUID.randomUUID();
return uuid;
}
/**
* Type 3 UUID Generation
*
* @throws UnsupportedEncodingException
*/
public static UUID generateType3UUID(String namespace, String name) throws UnsupportedEncodingException {
String source = namespace + name;
byte[] bytes = source.getBytes("UTF-8");
UUID uuid = UUID.nameUUIDFromBytes(bytes);
return uuid;
}
/**
* Type 5 UUID Generation
*
* @throws UnsupportedEncodingException
*/
public static UUID generateType5UUID(String namespace, String name) throws UnsupportedEncodingException {
String source = namespace + name;
byte[] bytes = source.getBytes("UTF-8");
UUID uuid = type5UUIDFromBytes(bytes);
return uuid;
}
public static UUID type5UUIDFromBytes(byte[] name) {
MessageDigest md;
try {
md = MessageDigest.getInstance("SHA-1");
} catch (NoSuchAlgorithmException nsae) {
throw new InternalError("MD5 not supported", nsae);
}
byte[] bytes = md.digest(name);
bytes[6] &= 0x0f; /* clear version */
bytes[6] |= 0x50; /* set to version 5 */
bytes[8] &= 0x3f; /* clear variant */
bytes[8] |= 0x80; /* set to IETF variant */
return constructType5UUID(bytes);
}
private static UUID constructType5UUID(byte[] data) {
long msb = 0;
long lsb = 0;
assert data.length == 16 : "data must be 16 bytes in length";
for (int i=0; i<8; i++)
msb = (msb << 8) | (data[i] & 0xff);
for (int i=8; i<16; i++)
lsb = (lsb << 8) | (data[i] & 0xff);
return new UUID(msb, lsb);
}
/**
* Unique Keys Generation Using Message Digest and Type 4 UUID
*
* @throws NoSuchAlgorithmException
* @throws UnsupportedEncodingException
*/
public static String generateUniqueKeysWithUUIDAndMessageDigest() throws NoSuchAlgorithmException, UnsupportedEncodingException {
MessageDigest salt = MessageDigest.getInstance("SHA-256");
salt.update(UUID.randomUUID()
.toString()
.getBytes("UTF-8"));
String digest = bytesToHex(salt.digest());
return digest;
}
public static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for (int j = 0; j < bytes.length; j++) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}
}
core-java/src/test/java/com/baeldung/classnotfoundexception/ClassNotFoundExceptionTest.java
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package com.baeldung.classnotfoundexception;
import org.junit.Test;
public class ClassNotFoundExceptionTest {
@Test(expected = ClassNotFoundException.class)
public void givenNoDriversInClassPath_whenLoadDrivers_thenClassNotFoundException() throws ClassNotFoundException {
Class.forName("oracle.jdbc.driver.OracleDriver");
}
}
core-java/src/test/java/com/baeldung/noclassdeffounderror/NoClassDefFoundErrorTest.java
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package com.baeldung.noclassdeffounderror;
import org.junit.Test;
public class NoClassDefFoundErrorTest {
@Test(expected = NoClassDefFoundError.class)
public void givenInitErrorInClass_whenloadClass_thenNoClassDefFoundError() {
NoClassDefFoundErrorExample sample = new NoClassDefFoundErrorExample();
sample.getClassWithInitErrors();
}
}
core-java/src/test/java/com/baeldung/regexp/EscapingCharsTest.java
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package com.baeldung.regexp;
import static junit.framework.TestCase.assertEquals;
import static org.junit.Assert.assertThat;
import static org.hamcrest.CoreMatchers.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.junit.Test;
public class EscapingCharsTest {
@Test
public void givenRegexWithDot_whenMatchingStr_thenMatches() {
String strInput = "foof";
String strRegex = "foo.";
assertEquals(true, strInput.matches(strRegex));
}
@Test
public void givenRegexWithDotEsc_whenMatchingStr_thenNotMatching() {
String strInput = "foof";
String strRegex = "foo\\.";
assertEquals(false, strInput.matches(strRegex));
}
@Test
public void givenRegexWithPipeEscaped_whenSplitStr_thenSplits() {
String strInput = "foo|bar|hello|world";
String strRegex = "\\Q|\\E";
assertEquals(4, strInput.split(strRegex).length);
}
@Test
public void givenRegexWithPipeEscQuoteMeth_whenSplitStr_thenSplits() {
String strInput = "foo|bar|hello|world";
String strRegex = "|";
assertEquals(4,strInput.split(Pattern.quote(strRegex)).length);
}
@Test
public void givenRegexWithDollar_whenReplacing_thenNotReplace() {
String strInput = "I gave $50 to my brother."
+ "He bought candy for $35. Now he has $15 left.";
String strRegex = "$";
String strReplacement = "£";
String output = "I gave £50 to my brother."
+ "He bought candy for £35. Now he has £15 left.";
Pattern p = Pattern.compile(strRegex);
Matcher m = p.matcher(strInput);
assertThat(output, not(equalTo(m.replaceAll(strReplacement))));
}
@Test
public void givenRegexWithDollarEsc_whenReplacing_thenReplace() {
String strInput = "I gave $50 to my brother."
+ "He bought candy for $35. Now he has $15 left.";
String strRegex = "\\$";
String strReplacement = "£";
String output = "I gave £50 to my brother."
+ "He bought candy for £35. Now he has £15 left.";
Pattern p = Pattern.compile(strRegex);
Matcher m = p.matcher(strInput);
assertEquals(output,m.replaceAll(strReplacement));
}
}
core-java/src/test/java/com/baeldung/stream/StreamAddUnitTest.java
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package com.baeldung.stream;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
public class StreamAddUnitTest {
@Test
public void givenStream_whenAppendingObject_thenAppended() {
Stream<String> anStream = Stream.of("a", "b", "c", "d", "e");
Stream<String> newStream = Stream.concat(anStream, Stream.of("A"));
List<String> resultList = newStream.collect(Collectors.toList());
assertEquals(resultList.get(resultList.size() - 1), "A");
}
@Test
public void givenStream_whenPrependingObject_thenPrepended() {
Stream<Integer> anStream = Stream.of(1, 2, 3, 4, 5);
Stream<Integer> newStream = Stream.concat(Stream.of(99), anStream);
assertEquals(newStream.findFirst()
.get(), (Integer) 99);
}
@Test
public void givenStream_whenInsertingObject_thenInserted() {
Stream<Double> anStream = Stream.of(1.1, 2.2, 3.3);
Stream<Double> newStream = insertInStream(anStream, 9.9, 3);
List<Double> resultList = newStream.collect(Collectors.toList());
assertEquals(resultList.get(3), (Double) 9.9);
}
public <T> Stream<T> insertInStream(Stream<T> stream, T elem, int index) {
List<T> result = stream.collect(Collectors.toList());
result.add(index, elem);
return result.stream();
}
}
core-java/src/test/java/com/baeldung/stream/StreamApiTest.java
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package com.baeldung.stream;
import static org.junit.Assert.assertEquals;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
public class StreamApiTest {
private StreamApi streamApi = new StreamApi();
@Test
public void givenList_whenGetLastElementUsingReduce_thenReturnLastElement() {
List<String> valueList = new ArrayList<String>();
valueList.add("Joe");
valueList.add("John");
valueList.add("Sean");
String last = streamApi.getLastElementUsingReduce(valueList);
assertEquals("Sean", last);
}
@Test
public void givenInfiniteStream_whenGetInfiniteStreamLastElementUsingReduce_thenReturnLastElement() {
Integer last = streamApi.getInfiniteStreamLastElementUsingReduce();
assertEquals(new Integer(19), last);
}
@Test
public void givenListAndCount_whenGetLastElementUsingSkip_thenReturnLastElement() {
List<String> valueList = new ArrayList<String>();
valueList.add("Joe");
valueList.add("John");
valueList.add("Sean");
String last = streamApi.getLastElementUsingSkip(valueList);
assertEquals("Sean", last);
}
}
core-java/src/test/java/org/baeldung/java/JavaRandomUnitTest.java
+3 -1
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@@ -167,9 +167,11 @@ public class JavaRandomUnitTest {
final int leftLimit = 97; // letter 'a'
final int rightLimit = 122; // letter 'z'
final int targetStringLength = 10;
final Random random = new Random();
final StringBuilder buffer = new StringBuilder(targetStringLength);
for (int i = 0; i < targetStringLength; i++) {
final int randomLimitedInt = leftLimit + (int) (new Random().nextFloat() * (rightLimit - leftLimit + 1));
final int randomLimitedInt = leftLimit + (int) (random.nextFloat() * (rightLimit - leftLimit + 1));
buffer.append((char) randomLimitedInt);
}
final String generatedString = buffer.toString();