Merge branch 'master' of https://github.com/eugenp/tutorials

2020-05-03 13:33:10 +03:00
parent 7feb9bfb1e df332afd65
commit 7b071a05e4
3894 changed files with 74875 additions and 39004 deletions
@@ -65,6 +65,7 @@ core-java-io/target_link.txt
 core-java/src/main/java/com/baeldung/manifest/MANIFEST.MF
 ethereum/logs/
 jmeter/src/main/resources/*-JMeter.csv
+ninja/devDb.mv.db

 **/node_modules/
 **/dist
@@ -72,8 +73,6 @@ jmeter/src/main/resources/*-JMeter.csv
 **/out-tsc
 **/nbproject/
 **/nb-configuration.xml
-core-scala/.cache-main
-core-scala/.cache-tests


 persistence-modules/hibernate5/transaction.log
@@ -22,10 +22,38 @@ This project is **a collection of small and focused tutorials** - each covering
 A strong focus of these is, of course, the Spring Framework - Spring, Spring Boot and Spring Security. 
 In additional to Spring, the modules here are covering a number of aspects in Java. 

+Profile based segregation
+====================
+
+We are using maven build profiles to segregate the huge list of individual projects we have in our repository.
+
+The projects are broadly divided into 3 list: first, second and heavy. 
+
+Next, they are segregated further on the basis of tests that we want to execute.
+
+Therefore, we have a total of 6 profiles:
+
+| Profile                 | Includes                    | Type of test enabled |
+| ----------------------- | --------------------------- | -------------------- |
+| default-first           | First set of projects       | *UnitTest            |
+| integration-lite-first  | First set of projects       | *IntegrationTest     |
+| default-second          | Second set of projects      | *UnitTest            |
+| integration-lite-second | Second set of projects      | *IntegrationTest     |
+| default-heavy           | Heavy/long running projects | *UnitTest            |
+| integration-heavy       | Heavy/long running projects | *IntegrationTest     |

 Building the project
 ====================
-To do the full build, do: `mvn clean install`
+
+Though it should not be needed often to build the entire repository at once because we are usually concerned with a specific module.
+
+But if we want to, we can invoke the below command from the root of the repository if we want to build the entire repository with only Unit Tests enabled:
+
+`mvn clean install -Pdefault-first,default-second,default-heavy`
+
+or if we want to build the entire repository with Integration Tests enabled, we can do:
+
+`mvn clean install -Pintegration-lite-first,integration-lite-second,integration-heavy`


 Building a single module
@@ -46,8 +74,18 @@ When you're working with an individual module, there's no need to import all of

 Running Tests
 =============
-The command `mvn clean install` will run the unit tests in a module.
-To run the integration tests, use the command `mvn clean install -Pintegration-lite-first`
+The command `mvn clean install` from within a module will run the unit tests in that module.
+For Spring modules this will also run the `SpringContextTest` if present.
+
+To run the integration tests, use the command:
+
+`mvn clean install -Pintegration-lite-first` or 
+
+`mvn clean install -Pintegration-lite-second` or 
+
+`mvn clean install -Pintegration-heavy`
+
+depending on the list where our module exists



@@ -1,7 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
-         xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+<project
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <artifactId>akka-http</artifactId>
    <name>akka-http</name>
@@ -1,6 +1,8 @@
 <?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">
+<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>akka-streams</artifactId>
    <name>akka-streams</name>
@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-genetic</artifactId>
    <version>0.0.1-SNAPSHOT</version>
@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-1</artifactId>
    <version>0.0.1-SNAPSHOT</version>
@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-2</artifactId>
    <version>0.0.1-SNAPSHOT</version>
@@ -13,6 +13,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Checking if a Java Graph has a Cycle](https://www.baeldung.com/java-graph-has-a-cycle)
 - [A Guide to the Folding Technique in Java](https://www.baeldung.com/folding-hashing-technique)
 - [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)
- [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)
 - [The K-Means Clustering Algorithm in Java](https://www.baeldung.com/java-k-means-clustering-algorithm)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-2) [[next -->]](/algorithms-miscellaneous-4)
@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-3</artifactId>
    <version>0.0.1-SNAPSHOT</version>
@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-4</artifactId>
    <version>0.0.1-SNAPSHOT</version>
@@ -10,7 +10,10 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
 - [Knapsack Problem Implementation in Java](https://www.baeldung.com/java-knapsack)
 - [How to Determine if a Binary Tree is Balanced](https://www.baeldung.com/java-balanced-binary-tree)
- [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
 - [Overview of Combinatorial Problems in Java](https://www.baeldung.com/java-combinatorial-algorithms)
 - [Prim’s Algorithm](https://www.baeldung.com/java-prim-algorithm)
- More articles: [[<-- prev]](/../algorithms-miscellaneous-4)
+- [Maximum Subarray Problem](https://www.baeldung.com/java-maximum-subarray)
+- [How to Merge Two Sorted Arrays](https://www.baeldung.com/java-merge-sorted-arrays)
+- [Median of Stream of Integers using Heap](https://www.baeldung.com/java-stream-integers-median-using-heap)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-4) [[next -->]](/../algorithms-miscellaneous-6)
+
@@ -1,6 +1,8 @@
 <?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">
+<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>algorithms-miscellaneous-5</artifactId>
    <version>0.0.1-SNAPSHOT</version>
@@ -23,12 +25,6 @@
            <artifactId>commons-math3</artifactId>
            <version>${commons-math3.version}</version>
        </dependency>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <version>${lombok.version}</version>
-            <scope>provided</scope>
-        </dependency>
        <dependency>
            <groupId>pl.allegro.finance</groupId>
            <artifactId>tradukisto</artifactId>
@@ -39,6 +35,11 @@
            <artifactId>guava</artifactId>
            <version>${guava.version}</version>
        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-commons</artifactId>
+            <version>${junit.platform.version}</version>
+        </dependency>

        <dependency>
            <groupId>org.assertj</groupId>
@@ -66,6 +67,7 @@
        <commons-codec.version>1.11</commons-codec.version>
        <commons-math3.version>3.6.1</commons-math3.version>
        <guava.version>28.1-jre</guava.version>
+        <junit.platform.version>1.6.0</junit.platform.version>
    </properties>

 </project>
@@ -0,0 +1,41 @@
+{
+	"nodes": 5,
+	"edges": 7,
+	"edgeList": [
+		{
+			"first": 0,
+			"second": 1,
+			"weight": 8
+		},
+		{
+			"first": 0,
+			"second": 2,
+			"weight": 5
+		},
+		{
+			"first": 1,
+			"second": 2,
+			"weight": 9
+		},
+		{
+			"first": 1,
+			"second": 3,
+			"weight": 11
+		},
+		{
+			"first": 2,
+			"second": 3,
+			"weight": 15
+		},
+		{
+			"first": 2,
+			"second": 4,
+			"weight": 10
+		},
+		{
+			"first": 3,
+			"second": 4,
+			"weight": 7
+		}
+	]
+}
@@ -0,0 +1,10 @@
+### Relevant Articles:
+
+- [Boruvka’s Algorithm for Minimum Spanning Trees](https://www.baeldung.com/java-boruvka-algorithm)
+- [Gradient Descent in Java](https://www.baeldung.com/java-gradient-descent)
+- [Kruskal’s Algorithm for Spanning Trees](https://www.baeldung.com/java-spanning-trees-kruskal)
+- [Balanced Brackets Algorithm in Java](https://www.baeldung.com/java-balanced-brackets-algorithm)
+- [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
+- [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
+- [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-5)
@@ -0,0 +1,52 @@
+<?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>algorithms-miscellaneous-6</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>algorithms-miscellaneous-6</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+    
+    <dependencies>
+    <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-commons</artifactId>
+            <version>${junit.platform.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${org.assertj.core.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
+    </dependencies>
+    
+    <properties>
+        <guava.version>28.1-jre</guava.version>
+        <org.assertj.core.version>3.9.0</org.assertj.core.version>
+        <junit.platform.version>1.6.0</junit.platform.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+    </properties>
+
+</project>
@@ -0,0 +1,84 @@
+package com.baeldung.algorithms.boruvka;
+
+import com.google.common.graph.EndpointPair;
+import com.google.common.graph.MutableValueGraph;
+import com.google.common.graph.ValueGraphBuilder;
+
+public class BoruvkaMST {
+
+    private static MutableValueGraph<Integer, Integer> mst = ValueGraphBuilder.undirected()
+        .build();
+    private static int totalWeight;
+
+    public BoruvkaMST(MutableValueGraph<Integer, Integer> graph) {
+
+        int size = graph.nodes().size();
+
+        UnionFind uf = new UnionFind(size);
+
+        // repeat at most log N times or until we have N-1 edges
+        for (int t = 1; t < size && mst.edges().size() < size - 1; t = t + t) {
+            
+            EndpointPair<Integer>[] closestEdgeArray = new EndpointPair[size];
+
+            // foreach tree in graph, find closest edge
+            for (EndpointPair<Integer> edge : graph.edges()) {
+                int u = edge.nodeU();
+                int v = edge.nodeV();
+                int uParent = uf.find(u);
+                int vParent = uf.find(v);
+                if (uParent == vParent) {
+                    continue; // same tree
+                }
+
+                int weight = graph.edgeValueOrDefault(u, v, 0);
+
+                if (closestEdgeArray[uParent] == null) {
+                    closestEdgeArray[uParent] = edge;
+                }
+                if (closestEdgeArray[vParent] == null) {
+                    closestEdgeArray[vParent] = edge;
+                }
+
+                int uParentWeight = graph.edgeValueOrDefault(closestEdgeArray[uParent].nodeU(), closestEdgeArray[uParent].nodeV(), 0);
+                int vParentWeight = graph.edgeValueOrDefault(closestEdgeArray[vParent].nodeU(), closestEdgeArray[vParent].nodeV(), 0);
+
+                if (weight < uParentWeight) {
+                    closestEdgeArray[uParent] = edge;
+                }
+                if (weight < vParentWeight) {
+                    closestEdgeArray[vParent] = edge;
+                }
+            }
+
+            // add newly discovered edges to MST
+            for (int i = 0; i < size; i++) {
+                EndpointPair<Integer> edge = closestEdgeArray[i];
+                if (edge != null) {
+                    int u = edge.nodeU();
+                    int v = edge.nodeV();
+                    int weight = graph.edgeValueOrDefault(u, v, 0);
+                    // don't add the same edge twice
+                    if (uf.find(u) != uf.find(v)) {
+                        mst.putEdgeValue(u, v, weight);
+                        totalWeight += weight;
+                        uf.union(u, v);
+                    }
+                }
+            }
+        }
+    }
+
+    public MutableValueGraph<Integer, Integer> getMST() {
+        return mst;
+    }
+
+    public int getTotalWeight() {
+        return totalWeight;
+    }
+
+    public String toString() {
+        return "MST: " + mst.toString() + " | Total Weight: " + totalWeight;
+    }
+
+}
@@ -0,0 +1,39 @@
+package com.baeldung.algorithms.boruvka;
+
+public class UnionFind {
+    private int[] parents;
+    private int[] ranks;
+
+    public UnionFind(int n) {
+        parents = new int[n];
+        ranks = new int[n];
+        for (int i = 0; i < n; i++) {
+            parents[i] = i;
+            ranks[i] = 0;
+        }
+    }
+
+    public int find(int u) {
+        while (u != parents[u]) {
+            u = parents[u];
+        }
+        return u;
+    }
+
+    public void union(int u, int v) {
+        int uParent = find(u);
+        int vParent = find(v);
+        if (uParent == vParent) {
+            return;
+        }
+
+        if (ranks[uParent] < ranks[vParent]) {
+            parents[uParent] = vParent;
+        } else if (ranks[uParent] > ranks[vParent]) {
+            parents[vParent] = uParent;
+        } else {
+            parents[vParent] = uParent;
+            ranks[uParent]++;
+        }
+    }
+}
@@ -0,0 +1,33 @@
+package com.baeldung.algorithms.gradientdescent;
+
+import java.util.function.Function;
+
+public class GradientDescent {
+
+    private final double precision = 0.000001;
+
+    public double findLocalMinimum(Function<Double, Double> f, double initialX) {
+        double stepCoefficient = 0.1;
+        double previousStep = 1.0;
+        double currentX = initialX;
+        double previousX = initialX;
+        double previousY = f.apply(previousX);
+        int iter = 100;
+
+        currentX += stepCoefficient * previousY;
+
+        while (previousStep > precision && iter > 0) {
+            iter--;
+            double currentY = f.apply(currentX);
+            if (currentY > previousY) {
+                stepCoefficient = -stepCoefficient / 2;
+            }
+            previousX = currentX;
+            currentX += stepCoefficient * previousY;
+            previousY = currentY;
+            previousStep = StrictMath.abs(currentX - previousX);
+        }
+        return currentX;
+    }
+
+}
--- a/Show More
+++ b/Show More