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Merge https://github.com/eugenp/tutorials

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ajay74984
2020-02-28 15:52:01 +01:00
parent 6e8bbfd9c3 107bf079f9
commit c10db7f625
659 changed files with 6939 additions and 11220 deletions
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blade/pom.xml
+1 -1
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@@ -106,7 +106,7 @@
<arguments>
<argument>java</argument>
<argument>-jar</argument>
<argument>sample-blade-app.jar</argument>
<argument>blade.jar</argument>
</arguments>
</configuration>
</execution>
core-java-modules/core-java-arrays-3/README.md
+5
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@@ -0,0 +1,5 @@
## Core Java Arrays (Part 3)
This module contains articles about Java arrays
## Relevant Articles
core-java-modules/core-java-arrays-3/pom.xml
+31
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@@ -0,0 +1,31 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-java-arrays-3</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-arrays-3</name>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-java</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<assertj.version>3.14.0</assertj.version>
</properties>
</project>
core-java-modules/core-java-arrays-3/src/test/java/com/baeldung/arrays/deepequals/ArraysDeepEqualsUnitTest.java
+96
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@@ -0,0 +1,96 @@
package com.baeldung.arrays.deepequals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import java.util.Arrays;
import java.util.Objects;
import org.junit.jupiter.api.Test;
public class ArraysDeepEqualsUnitTest {
class Person {
private int id;
private String name;
private int age;
Person(int id, String name, int age) {
this.id = id;
this.name = name;
this.age = age;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!(obj instanceof Person))
return false;
Person person = (Person) obj;
return id == person.id && name.equals(person.name) && age == person.age;
}
@Override
public int hashCode() {
return Objects.hash(id, name, age);
}
}
@Test
void givenTwoUnidimensionalObjectTypeArrays_whenUsingEqualsAndDeepEquals_thenBothShouldReturnTrue() {
Object[] anArray = new Object[] { "string1", "string2", "string3" };
Object[] anotherArray = new Object[] { "string1", "string2", "string3" };
assertTrue(Arrays.equals(anArray, anotherArray));
assertTrue(Arrays.deepEquals(anArray, anotherArray));
}
@Test
void givenTwoUnidimensionalObjectTypeArraysWithNullElements_whenUsingEqualsAndDeepEquals_thenBothShouldReturnTrue() {
Object[] anArray = new Object[] { "string1", null, "string3" };
Object[] anotherArray = new Object[] { "string1", null, "string3" };
assertTrue(Arrays.equals(anArray, anotherArray));
assertTrue(Arrays.deepEquals(anArray, anotherArray));
}
@Test
void givenTwoUnidimensionalObjectTypeArraysWithNestedElements_whenUsingEqualsAndDeepEquals_thenShouldReturnDifferently() {
Object[] anArray = new Object[] { "string1", null, new String[] { "nestedString1", "nestedString2" } };
Object[] anotherArray = new Object[] { "string1", null, new String[] { "nestedString1", "nestedString2" } };
assertFalse(Arrays.equals(anArray, anotherArray));
assertTrue(Arrays.deepEquals(anArray, anotherArray));
}
@Test
void givenTwoMultidimensionalPrimitiveTypeArrays_whenUsingEqualsAndDeepEquals_thenBothShouldReturnDifferently() {
int[][] anArray = { { 1, 2, 3 }, { 4, 5, 6, 9 }, { 7 } };
int[][] anotherArray = { { 1, 2, 3 }, { 4, 5, 6, 9 }, { 7 } };
assertFalse(Arrays.equals(anArray, anotherArray));
assertTrue(Arrays.deepEquals(anArray, anotherArray));
}
@Test
void givenTwoMultidimensionalObjectTypeArrays_whenUsingEqualsAndDeepEquals_thenBothShouldReturnDifferently() {
Person personArray1[][] = { { new Person(1, "John", 22), new Person(2, "Mike", 23) }, { new Person(3, "Steve", 27), new Person(4, "Gary", 28) } };
Person personArray2[][] = { { new Person(1, "John", 22), new Person(2, "Mike", 23) }, { new Person(3, "Steve", 27), new Person(4, "Gary", 28) } };
assertFalse(Arrays.equals(personArray1, personArray2));
assertTrue(Arrays.deepEquals(personArray1, personArray2));
}
@Test
void givenTwoMultidimensionalObjectTypeArrays_whenUsingDeepEqualsFromObjectsAndArraysClasses_thenBothShouldReturnTrue() {
Person personArray1[][] = { { new Person(1, "John", 22), new Person(2, "Mike", 23) }, { new Person(3, "Steve", 27), new Person(4, "Gary", 28) } };
Person personArray2[][] = { { new Person(1, "John", 22), new Person(2, "Mike", 23) }, { new Person(3, "Steve", 27), new Person(4, "Gary", 28) } };
assertTrue(Objects.deepEquals(personArray1, personArray2));
assertTrue(Arrays.deepEquals(personArray1, personArray2));
}
}
core-java-modules/core-java-arrays/src/main/java/com/baeldung/array/Find2ndLargestInArray.java
-20
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@@ -1,20 +0,0 @@
package com.baeldung.array;
public class Find2ndLargestInArray {
public static int find2ndLargestElement(int[] array) {
int maxElement = array[0];
int secondLargestElement = -1;
for (int index = 0; index < array.length; index++) {
if (maxElement <= array[index]) {
secondLargestElement = maxElement;
maxElement = array[index];
} else if (secondLargestElement < array[index]) {
secondLargestElement = array[index];
}
}
return secondLargestElement;
}
}
core-java-modules/core-java-arrays/src/main/java/com/baeldung/array/FindElementInArray.java
-22
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@@ -1,22 +0,0 @@
package com.baeldung.array;
import java.util.Arrays;
public class FindElementInArray {
public static boolean findGivenElementInArrayWithoutUsingStream(int[] array, int element) {
boolean actualResult = false;
for (int index = 0; index < array.length; index++) {
if (element == array[index]) {
actualResult = true;
break;
}
}
return actualResult;
}
public static boolean findGivenElementInArrayUsingStream(int[] array, int element) {
return Arrays.stream(array).filter(x -> element == x).findFirst().isPresent();
}
}
core-java-modules/core-java-arrays/src/test/java/com/baeldung/array/Find2ndLargestInArrayUnitTest.java
-16
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@@ -1,16 +0,0 @@
package com.baeldung.array;
import org.junit.Assert;
import org.junit.Test;
public class Find2ndLargestInArrayUnitTest {
@Test
public void givenAnIntArray_thenFind2ndLargestElement() {
int[] array = { 1, 3, 24, 16, 87, 20 };
int expected2ndLargest = 24;
int actualSecondLargestElement = Find2ndLargestInArray.find2ndLargestElement(array);
Assert.assertEquals(expected2ndLargest, actualSecondLargestElement);
}
}
core-java-modules/core-java-arrays/src/test/java/com/baeldung/array/FindElementInArrayUnitTest.java
-35
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@@ -1,35 +0,0 @@
package com.baeldung.array;
import org.junit.Assert;
import org.junit.Test;
public class FindElementInArrayUnitTest {
@Test
public void givenAnIntArray_whenNotUsingStream_thenFindAnElement() {
int[] array = { 1, 3, 4, 8, 19, 20 };
int element = 19;
boolean expectedResult = true;
boolean actualResult = FindElementInArray.findGivenElementInArrayWithoutUsingStream(array, element);
Assert.assertEquals(expectedResult, actualResult);
element = 78;
expectedResult = false;
actualResult = FindElementInArray.findGivenElementInArrayWithoutUsingStream(array, element);
Assert.assertEquals(expectedResult, actualResult);
}
@Test
public void givenAnIntArray_whenUsingStream_thenFindAnElement() {
int[] array = { 15, 16, 12, 18 };
int element = 16;
boolean expectedResult = true;
boolean actualResult = FindElementInArray.findGivenElementInArrayUsingStream(array, element);
Assert.assertEquals(expectedResult, actualResult);
element = 20;
expectedResult = false;
actualResult = FindElementInArray.findGivenElementInArrayUsingStream(array, element);
Assert.assertEquals(expectedResult, actualResult);
}
}
core-java-modules/core-java-io-2/README.md
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@@ -11,5 +11,5 @@ This module contains articles about core Java input and output (IO)
- [List Files in a Directory in Java](https://www.baeldung.com/java-list-directory-files)
- [Java – Append Data to a File](https://www.baeldung.com/java-append-to-file)
- [How to Copy a File with Java](https://www.baeldung.com/java-copy-file)
- [Create a Directory in Java](https://www.baeldung.com/java-create-directory)
- [Create a Directory in Java](https://www.baeldung.com/java-create-directory)
- [[<-- Prev]](/core-java-modules/core-java-io)
core-java-modules/core-java-io/src/test/java/com/baeldung/readfile/FileOperationsManualTest.java
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@@ -1,134 +0,0 @@
package com.baeldung.readfile;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.hamcrest.CoreMatchers;
import org.hamcrest.Matchers;
import org.junit.Test;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
public class FileOperationsManualTest {
@Test
public void givenFileName_whenUsingClassloader_thenFileData() throws IOException {
String expectedData = "Hello World from fileTest.txt!!!";
ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("fileTest.txt").getFile());
InputStream inputStream = new FileInputStream(file);
String data = readFromInputStream(inputStream);
assertEquals(expectedData, data.trim());
}
@Test
public void givenFileNameAsAbsolutePath_whenUsingClasspath_thenFileData() throws IOException {
String expectedData = "Hello World from fileTest.txt!!!";
Class clazz = FileOperationsManualTest.class;
InputStream inputStream = clazz.getResourceAsStream("/fileTest.txt");
String data = readFromInputStream(inputStream);
assertEquals(expectedData, data.trim());
}
@Test
public void givenFileName_whenUsingJarFile_thenFileData() throws IOException {
String expectedData = "MIT License";
Class clazz = Matchers.class;
InputStream inputStream = clazz.getResourceAsStream("/LICENSE.txt");
String data = readFromInputStream(inputStream);
assertThat(data.trim(), CoreMatchers.containsString(expectedData));
}
@Test
public void givenURLName_whenUsingURL_thenFileData() throws IOException {
String expectedData = "Example Domain";
URL urlObject = new URL("http://www.example.com/");
URLConnection urlConnection = urlObject.openConnection();
InputStream inputStream = urlConnection.getInputStream();
String data = readFromInputStream(inputStream);
assertThat(data.trim(), CoreMatchers.containsString(expectedData));
}
@Test
public void givenFileName_whenUsingFileUtils_thenFileData() throws IOException {
String expectedData = "Hello World from fileTest.txt!!!";
ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("fileTest.txt").getFile());
String data = FileUtils.readFileToString(file, "UTF-8");
assertEquals(expectedData, data.trim());
}
@Test
public void givenFilePath_whenUsingFilesReadAllBytes_thenFileData() throws IOException, URISyntaxException {
String expectedData = "Hello World from fileTest.txt!!!";
Path path = Paths.get(getClass().getClassLoader().getResource("fileTest.txt").toURI());
byte[] fileBytes = Files.readAllBytes(path);
String data = new String(fileBytes);
assertEquals(expectedData, data.trim());
}
@Test
public void givenFilePath_whenUsingFilesLines_thenFileData() throws IOException, URISyntaxException {
String expectedData = "Hello World from fileTest.txt!!!";
Path path = Paths.get(getClass().getClassLoader().getResource("fileTest.txt").toURI());
Stream<String> lines = Files.lines(path);
String data = lines.collect(Collectors.joining("\n"));
lines.close();
assertEquals(expectedData, data.trim());
}
private String readFromInputStream(InputStream inputStream) throws IOException {
StringBuilder resultStringBuilder = new StringBuilder();
try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream))) {
String line;
while ((line = bufferedReader.readLine()) != null) {
resultStringBuilder.append(line).append("\n");
}
}
return resultStringBuilder.toString();
}
@Test
public void givenFileName_whenUsingIOUtils_thenFileData() throws IOException {
String expectedData = "This is a content of the file";
FileInputStream fis = new FileInputStream("src/test/resources/fileToRead.txt");
String data = IOUtils.toString(fis, "UTF-8");
assertEquals(expectedData, data.trim());
}
}
core-java-modules/core-java-io/src/test/java/com/baeldung/readfile/JavaReadFromFileUnitTest.java
+149 -53
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@@ -1,11 +1,15 @@
package com.baeldung.readfile;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.hamcrest.CoreMatchers;
import org.hamcrest.Matchers;
import org.junit.Test;
import org.junit.Ignore;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.*;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
@@ -13,55 +17,148 @@ import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Scanner;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
public class JavaReadFromFileUnitTest {
private static final Logger LOG = LoggerFactory.getLogger(JavaReadFromFileUnitTest.class);
@Test
public void whenReadWithBufferedReader_thenCorrect() throws IOException {
final String expected_value = "Hello world";
final String expected_value = "Hello, world!";
final BufferedReader reader = new BufferedReader(new FileReader("src/test/resources/test_read.in"));
final BufferedReader reader = new BufferedReader(new FileReader("src/test/resources/fileTest.txt"));
final String currentLine = reader.readLine();
reader.close();
assertEquals(expected_value, currentLine);
}
@Test
public void givenFileName_whenUsingClassloader_thenFileData() throws IOException {
String expectedData = "Hello, world!";
ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("fileTest.txt").getFile());
InputStream inputStream = new FileInputStream(file);
String data = readFromInputStream(inputStream);
assertEquals(expectedData, data.trim());
}
@Test
public void givenFileNameAsAbsolutePath_whenUsingClasspath_thenFileData() throws IOException {
String expectedData = "Hello, world!";
Class clazz = JavaReadFromFileUnitTest.class;
InputStream inputStream = clazz.getResourceAsStream("/fileTest.txt");
String data = readFromInputStream(inputStream);
assertEquals(expectedData, data.trim());
}
@Test
public void givenFileName_whenUsingJarFile_thenFileData() throws IOException {
String expectedData = "BSD License";
Class clazz = Matchers.class;
InputStream inputStream = clazz.getResourceAsStream("/LICENSE.txt");
String data = readFromInputStream(inputStream);
assertThat(data.trim(), CoreMatchers.containsString(expectedData));
}
@Test
public void givenURLName_whenUsingURL_thenFileData() throws IOException {
String expectedData = "Example Domain";
URL urlObject = new URL("http://www.example.com/");
URLConnection urlConnection = urlObject.openConnection();
InputStream inputStream = urlConnection.getInputStream();
String data = readFromInputStream(inputStream);
assertThat(data.trim(), CoreMatchers.containsString(expectedData));
}
@Test
public void givenFileName_whenUsingFileUtils_thenFileData() throws IOException {
String expectedData = "Hello, world!";
ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("fileTest.txt").getFile());
String data = FileUtils.readFileToString(file, "UTF-8");
assertEquals(expectedData, data.trim());
}
@Test
public void givenFilePath_whenUsingFilesReadAllBytes_thenFileData() throws IOException, URISyntaxException {
String expectedData = "Hello, world!";
Path path = Paths.get(getClass().getClassLoader().getResource("fileTest.txt").toURI());
byte[] fileBytes = Files.readAllBytes(path);
String data = new String(fileBytes);
assertEquals(expectedData, data.trim());
}
@Test
public void givenFilePath_whenUsingFilesLines_thenFileData() throws IOException, URISyntaxException {
String expectedData = "Hello, world!";
Path path = Paths.get(getClass().getClassLoader().getResource("fileTest.txt").toURI());
Stream<String> lines = Files.lines(path);
String data = lines.collect(Collectors.joining("\n"));
lines.close();
assertEquals(expectedData, data.trim());
}
@Test
public void givenFileName_whenUsingIOUtils_thenFileData() throws IOException {
String expectedData = "Hello, world!";
FileInputStream fis = new FileInputStream("src/test/resources/fileTest.txt");
String data = IOUtils.toString(fis, "UTF-8");
assertEquals(expectedData, data.trim());
}
@Test
public void whenReadWithScanner_thenCorrect() throws IOException {
final Scanner scanner = new Scanner(new File("src/test/resources/test_read1.in"));
final Scanner scanner = new Scanner(new File("src/test/resources/fileTest.txt"));
scanner.useDelimiter(" ");
assertTrue(scanner.hasNext());
assertEquals("Hello", scanner.next());
assertEquals("world", scanner.next());
assertEquals(1, scanner.nextInt());
assertEquals("Hello,", scanner.next());
assertEquals("world!", scanner.next());
scanner.close();
}
@Test
public void whenReadWithScannerTwoDelimiters_thenCorrect() throws IOException {
final Scanner scanner = new Scanner(new File("src/test/resources/test_read2.in"));
scanner.useDelimiter(",| ");
final Scanner scanner = new Scanner(new File("src/test/resources/fileTest.txt"));
scanner.useDelimiter("\\s|,");
assertTrue(scanner.hasNextInt());
assertEquals(2, scanner.nextInt());
assertEquals(3, scanner.nextInt());
assertEquals(4, scanner.nextInt());
assertTrue(scanner.hasNext());
assertEquals("Hello", scanner.next());
assertEquals("", scanner.next());
assertEquals("world!", scanner.next());
scanner.close();
}
@Test
public void whenReadWithStreamTokenizer_thenCorrectTokens() throws IOException {
final FileReader reader = new FileReader("src/test/resources/test_read3.in");
final FileReader reader = new FileReader("src/test/resources/fileTestTokenizer.txt");
final StreamTokenizer tokenizer = new StreamTokenizer(reader);
tokenizer.nextToken();
@@ -78,49 +175,36 @@ public class JavaReadFromFileUnitTest {
@Test
public void whenReadWithDataInputStream_thenCorrect() throws IOException {
final String expected_value = "Hello";
String expectedValue = "Hello, world!";
String file ="src/test/resources/fileTest.txt";
String result;
final DataInputStream reader = new DataInputStream(new FileInputStream("src/test/resources/test_read4.in"));
result = reader.readUTF();
reader.close();
String result = null;
assertEquals(expected_value, result);
}
DataInputStream reader = new DataInputStream(new FileInputStream(file));
int nBytesToRead = reader.available();
if(nBytesToRead > 0) {
byte[] bytes = new byte[nBytesToRead];
reader.read(bytes);
result = new String(bytes);
}
public void whenReadTwoFilesWithSequenceInputStream_thenCorrect() throws IOException {
final int expected_value1 = 2000;
final int expected_value2 = 5000;
final FileInputStream stream1 = new FileInputStream("src/test/resources/test_read5.in");
final FileInputStream stream2 = new FileInputStream("src/test/resources/test_read6.in");
final SequenceInputStream sequence = new SequenceInputStream(stream1, stream2);
final DataInputStream reader = new DataInputStream(sequence);
assertEquals(expected_value1, reader.readInt());
assertEquals(expected_value2, reader.readInt());
reader.close();
stream2.close();
assertEquals(expectedValue, result);
}
@Test
@Ignore // TODO
public void whenReadUTFEncodedFile_thenCorrect() throws IOException {
final String expected_value = "青空";
final BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("src/test/resources/test_read7.in"), "UTF-8"));
final BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("src/test/resources/fileTestUtf8.txt"), "UTF-8"));
final String currentLine = reader.readLine();
reader.close();
LOG.debug(currentLine);
assertEquals(expected_value, currentLine);
}
@Test
public void whenReadFileContentsIntoString_thenCorrect() throws IOException {
final String expected_value = "Hello world \n Test line \n";
final BufferedReader reader = new BufferedReader(new FileReader("src/test/resources/test_read8.in"));
final String expected_value = "Hello, world!\n";
final BufferedReader reader = new BufferedReader(new FileReader("src/test/resources/fileTest.txt"));
final StringBuilder builder = new StringBuilder();
String currentLine = reader.readLine();
while (currentLine != null) {
@@ -136,8 +220,8 @@ public class JavaReadFromFileUnitTest {
@Test
public void whenReadWithFileChannel_thenCorrect() throws IOException {
final String expected_value = "Hello world";
final RandomAccessFile reader = new RandomAccessFile("src/test/resources/test_read.in", "r");
final String expected_value = "Hello, world!";
final RandomAccessFile reader = new RandomAccessFile("src/test/resources/fileTest.txt", "r");
final FileChannel channel = reader.getChannel();
int bufferSize = 1024;
@@ -154,8 +238,8 @@ public class JavaReadFromFileUnitTest {
@Test
public void whenReadSmallFileJava7_thenCorrect() throws IOException {
final String expected_value = "Hello world";
final Path path = Paths.get("src/test/resources/test_read.in");
final String expected_value = "Hello, world!";
final Path path = Paths.get("src/test/resources/fileTest.txt");
final String read = Files.readAllLines(path, Charset.defaultCharset()).get(0);
assertEquals(expected_value, read);
@@ -163,12 +247,24 @@ public class JavaReadFromFileUnitTest {
@Test
public void whenReadLargeFileJava7_thenCorrect() throws IOException {
final String expected_value = "Hello world";
final String expected_value = "Hello, world!";
final Path path = Paths.get("src/test/resources/test_read.in");
final Path path = Paths.get("src/test/resources/fileTest.txt");
final BufferedReader reader = Files.newBufferedReader(path, Charset.defaultCharset());
final String line = reader.readLine();
assertEquals(expected_value, line);
}
private String readFromInputStream(InputStream inputStream) throws IOException {
StringBuilder resultStringBuilder = new StringBuilder();
try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream))) {
String line;
while ((line = bufferedReader.readLine()) != null) {
resultStringBuilder.append(line).append("\n");
}
}
return resultStringBuilder.toString();
}
}
core-java-modules/core-java-io/src/test/resources/fileTest.txt
+1 -1
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@@ -1 +1 @@
Hello World from fileTest.txt!!!
Hello, world!
core-java-modules/core-java-io/src/test/resources/test_read3.in → core-java-modules/core-java-io/src/test/resources/fileTestTokenizer.txt
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core-java-modules/core-java-io/src/test/resources/test_read7.in → core-java-modules/core-java-io/src/test/resources/fileTestUtf8.txt
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core-java-modules/core-java-io/src/test/resources/test_read1.in
-1
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@@ -1 +0,0 @@
Hello world 1
core-java-modules/core-java-io/src/test/resources/test_read2.in
-1
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@@ -1 +0,0 @@
2,3 4
core-java-modules/core-java-io/src/test/resources/test_read4.in
BIN
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Binary file not shown.
core-java-modules/core-java-io/src/test/resources/test_read8.in
-2
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@@ -1,2 +0,0 @@
Hello world
Test line
core-java-modules/core-java-nio-2/hard_link.txt
-10000
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File diff suppressed because it is too large Load Diff
core-java-modules/core-java-nio-2/src/main/java/com/baeldung/lock/FileLocks.java
+148
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@@ -0,0 +1,148 @@
package com.baeldung.lock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.channels.NonReadableChannelException;
import java.nio.channels.NonWritableChannelException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
public class FileLocks {
private static final Logger LOG = LoggerFactory.getLogger(FileLocks.class);
// Write locks
/**
* Trying to get an exclusive lock on a read-only FileChannel won't work.
*/
static void getExclusiveLockFromInputStream() throws IOException {
Path path = Files.createTempFile("foo", "txt");
try (FileInputStream fis = new FileInputStream(path.toFile());
FileLock lock = fis.getChannel()
.lock()) {
LOG.debug("This won't happen");
} catch (NonWritableChannelException e) {
LOG.error("The channel obtained through a FileInputStream isn't writable. You can't obtain an exclusive lock on it!");
throw e;
}
}
/**
* Gets an exclusive lock from a RandomAccessFile. Works because the file is writable.
* @param from beginning of the locked region
* @param size how many bytes to lock
* @return A lock object representing the newly-acquired lock
* @throws IOException if there is a problem creating the temporary file
*/
static FileLock getExclusiveLockFromRandomAccessFile(long from, long size) throws IOException {
Path path = Files.createTempFile("foo", "txt");
try (RandomAccessFile file = new RandomAccessFile(path.toFile(), "rw");
FileLock lock = file.getChannel()
.lock(from, size, false)) {
if (lock.isValid()) {
LOG.debug("This is a valid exclusive lock");
return lock;
}
return null;
} catch (Exception e) {
LOG.error(e.getMessage());
}
return null;
}
/**
* Acquires an exclusive lock on a file region.
* @param from beginning of the locked region
* @param size how many bytes to lock
* @return A lock object representing the newly-acquired lock
* @throws IOException if there is a problem creating the temporary file
*/
static FileLock getExclusiveLockFromFileChannelOpen(long from, long size) throws IOException {
Path path = Files.createTempFile("foo", "txt");
try (FileChannel channel = FileChannel.open(path, StandardOpenOption.APPEND); FileLock lock = channel.lock(from, size, false)) {
String text = "Hello, world.";
ByteBuffer buffer = ByteBuffer.allocate(text.length() + System.lineSeparator()
.length());
buffer.put((text + System.lineSeparator()).getBytes(StandardCharsets.UTF_8));
buffer.flip();
while (buffer.hasRemaining()) {
channel.write(buffer, channel.size());
}
LOG.debug("This was written to the file");
Files.lines(path)
.forEach(LOG::debug);
return lock;
}
}
// Read locks
/**
* Trying to get a shared lock on a write-only FileChannel won't work.
*/
static void getReadLockFromOutputStream() throws IOException {
Path path = Files.createTempFile("foo", "txt");
try (FileOutputStream fis = new FileOutputStream(path.toFile());
FileLock lock = fis.getChannel()
.lock(0, Long.MAX_VALUE, true)) {
LOG.debug("This won't happen");
} catch (NonReadableChannelException e) {
LOG.error("The channel obtained through a FileOutputStream isn't readable. " + "You can't obtain an shared lock on it!");
throw e;
}
}
/**
* Gets a lock from an <tt>InputStream</tt>.
* @param from beginning of the locked region
* @param size how many bytes to lock
* @return A lock object representing the newly-acquired lock
* @throws IOException if there is a problem creating the temporary file
*/
static FileLock getReadLockFromInputStream(long from, long size) throws IOException {
Path path = Files.createTempFile("foo", "txt");
try (FileInputStream fis = new FileInputStream(path.toFile());
FileLock lock = fis.getChannel()
.lock(from, size, true)) {
if (lock.isValid()) {
LOG.debug("This is a valid shared lock");
return lock;
}
return null;
}
}
/**
* Gets an exclusive lock from a RandomAccessFile. Works because the file is readable.
* @param from beginning of the locked region
* @param size how many bytes to lock
* @return A lock object representing the newly-acquired lock
* @throws IOException if there is a problem creating the temporary file
*/
static FileLock getReadLockFromRandomAccessFile(long from, long size) throws IOException {
Path path = Files.createTempFile("foo", "txt");
try (RandomAccessFile file = new RandomAccessFile(path.toFile(), "r"); // could also be "rw", but "r" is sufficient for reading
FileLock lock = file.getChannel()
.lock(from, size, true)) {
if (lock.isValid()) {
LOG.debug("This is a valid shared lock");
return lock;
}
} catch (Exception e) {
LOG.error(e.getMessage());
}
return null;
}
}
core-java-modules/core-java-nio-2/src/test/java/com/baeldung/lock/FileLocksUnitTest.java
+54
View File
@@ -0,0 +1,54 @@
package com.baeldung.lock;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.io.IOException;
import java.nio.channels.FileLock;
import java.nio.channels.NonReadableChannelException;
import java.nio.channels.NonWritableChannelException;
import org.junit.jupiter.api.Test;
class FileLocksUnitTest {
@Test
void givenAnInputStream_whenGetWriteLock_thenThrowNonWritableChannelException() {
assertThrows(NonWritableChannelException.class, () -> FileLocks.getExclusiveLockFromInputStream());
}
@Test
void givenARandomAccessFileWithReadWriteAccess_whenGetWriteLock_thenLock() throws IOException {
FileLock lock = FileLocks.getExclusiveLockFromRandomAccessFile(0, 10);
assertNotNull(lock);
assertFalse(lock.isShared());
}
@Test
void givenAPath_whenGetExclusiveLock_thenLock() throws IOException {
FileLock lock = FileLocks.getExclusiveLockFromFileChannelOpen(0, 10);
assertNotNull(lock);
assertFalse(lock.isShared());
}
@Test
void givenAFileOutputStream_whenGetSharedLock_thenThrowNonReadableChannelException() {
assertThrows(NonReadableChannelException.class, FileLocks::getReadLockFromOutputStream);
}
@Test
void givenAnInputStream_whenGetSharedLock_thenLock() throws IOException {
FileLock lock = FileLocks.getReadLockFromInputStream(0, 10);
assertNotNull(lock);
assertTrue(lock.isShared());
}
@Test
void givenARandomAccessFile_whenGetSharedLock_thenLock() throws IOException {
FileLock lock = FileLocks.getReadLockFromRandomAccessFile(0, 10);
assertNotNull(lock);
assertTrue(lock.isShared());
}
}
core-java-modules/core-java/README.md
+1 -1
View File
@@ -11,7 +11,7 @@
- [Introduction to Java Serialization](http://www.baeldung.com/java-serialization)
- [Guide to UUID in Java](http://www.baeldung.com/java-uuid)
- [Creating a Java Compiler Plugin](http://www.baeldung.com/java-build-compiler-plugin)
- [Quick Guide to Java Stack](http://www.baeldung.com/java-stack)
- [Quick Guide to the Java Stack](http://www.baeldung.com/java-stack)
- [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)
- [Introduction to Javadoc](http://www.baeldung.com/javadoc)
- [Guide to the Externalizable Interface in Java](http://www.baeldung.com/java-externalizable)
core-java-modules/core-java-date-operations-2/src/main/java/com/baeldung/timer/DatabaseMigrationTask.java → core-java-modules/core-java/src/main/java/com/baeldung/timer/DatabaseMigrationTask.java
View File
core-java-modules/core-java-date-operations-2/src/main/java/com/baeldung/timer/NewsletterTask.java → core-java-modules/core-java/src/main/java/com/baeldung/timer/NewsletterTask.java
View File
core-java-modules/core-java-date-operations-2/src/test/java/com/baeldung/timer/DatabaseMigrationTaskUnitTest.java → core-java-modules/core-java/src/test/java/com/baeldung/timer/DatabaseMigrationTaskUnitTest.java
View File
core-java-modules/core-java/src/test/java/com/baeldung/JavaTimerLongRunningUnitTest.java → core-java-modules/core-java/src/test/java/com/baeldung/timer/JavaTimerLongRunningUnitTest.java
+1 -1
View File
@@ -1,4 +1,4 @@
package com.baeldung;
package com.baeldung.timer;
import org.junit.Test;
import org.slf4j.Logger;
core-java-modules/core-java-date-operations-2/src/test/java/com/baeldung/timer/NewsletterTaskUnitTest.java → core-java-modules/core-java/src/test/java/com/baeldung/timer/NewsletterTaskUnitTest.java
View File
core-java-modules/pom.xml
+1
View File
@@ -31,6 +31,7 @@
<module>core-java-annotations</module>
<module>core-java-arrays</module>
<module>core-java-arrays-2</module>
<module>core-java-arrays-3</module>
<module>core-java-collections</module>
<module>core-java-collections-2</module>
core-kotlin-modules/core-kotlin-2/README.md
+1
View File
@@ -5,4 +5,5 @@ This module contains articles about Kotlin core features.
### Relevant articles:
- [Working with Dates in Kotlin](https://www.baeldung.com/kotlin-dates)
- [Kotlin Ternary Conditional Operator](https://www.baeldung.com/kotlin-ternary-operator)
- [Sequences in Kotlin](https://www.baeldung.com/kotlin/sequences)
- [[<-- Prev]](/core-kotlin-modules/core-kotlin)
core-kotlin-modules/core-kotlin/README.md
+3
View File
@@ -13,4 +13,7 @@ This module contains articles about Kotlin core features.
- [Implementing a Binary Tree in Kotlin](https://www.baeldung.com/kotlin-binary-tree)
- [JUnit 5 for Kotlin Developers](https://www.baeldung.com/junit-5-kotlin)
- [Converting Kotlin Data Class from JSON using GSON](https://www.baeldung.com/kotlin-json-convert-data-class)
- [Fuel HTTP Library with Kotlin](https://www.baeldung.com/kotlin-fuel)
- [Introduction to Kovenant Library for Kotlin](https://www.baeldung.com/kotlin-kovenant)
- [Dependency Injection for Kotlin with Injekt](https://www.baeldung.com/kotlin-dependency-injection-with-injekt)
- [[More --> ]](/core-kotlin-modules/core-kotlin-2)

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