Restore Code Formatting Checks (williamfiset#383)

* Replace Sherter with Spotless

* Update CI settings to use Spotless

* Move test runner to JDK 11

* Apply Google Java format to all existing files

Author: syoon2

.github/workflows/gradle.yml

@@ -19,10 +19,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-    - name: Set up JDK 1.8
+    - name: Set up JDK 11
       uses: actions/setup-java@v3
       with:
-        java-version: 8
+        java-version: 11
         distribution: 'temurin'
         cache: 'gradle'
     - name: Validate Gradle Wrapper
@@ -46,25 +46,21 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-    - name: Set up JDK 1.8
+    - name: Set up JDK 11
       uses: actions/setup-java@v3
       with:
-        java-version: 8
+        java-version: 11
         distribution: 'temurin'
         cache: 'gradle'
     - name: Validate Gradle Wrapper
       uses: gradle/wrapper-validation-action@v1
-    # The google formatter is broken atm. Disabling for now.
     - name: Verify all Java files are formatted correctly according to the Google Java Style Guide using Gradle
       uses: gradle/gradle-build-action@v2
-      if: ${{ false }}
       id: verifygooglejavaformat
       with:
         gradle-version: wrapper
-        arguments: verifyGoogleJavaFormat
+        arguments: spotlessJavaCheck
     - name: Create summary if format check failed
-      if: ${{ false }}
-      # Enable this when Google Java formatter is enabled
-      # if: ${{ steps.verifygooglejavaformat.outcome == 'failure' }}
+      if: ${{ steps.verifygooglejavaformat.outcome == 'failure' }}
       run: |
-        echo "Run the command `./gradlew goJF` to fix Java formatting." >> $GITHUB_STEP_SUMMARY
+        echo "Run the command `./gradlew spotlessApply` to fix Java formatting." >> $GITHUB_STEP_SUMMARY

build.gradle

@@ -7,14 +7,12 @@ buildscript {
 }
 
 plugins {
-  // https://github.com/sherter/google-java-format-gradle-plugin
-  // id "com.github.sherter.google-java-format" version "0.9"
+  // https://github.com/diffplug/spotless
+  id("com.diffplug.spotless") version "6.18.0"
 }
 
 apply plugin: 'java'
 apply plugin: 'application'
-// Formatting tool doesn't support Java 17+
-// apply plugin: "com.github.sherter.google-java-format"
 
 mainClassName = findProperty("main") ?: "com.williamfiset.algorithms.${findProperty("algorithm") ?: 'missingPackage.missingClass'}"
 
@@ -44,6 +42,12 @@ dependencies {
   testImplementation "org.mockito:mockito-core:5.+"
 }
 
+spotless {
+  java {
+    googleJavaFormat()
+  }
+}
+
 test {
   dependsOn cleanTest
   testLogging.showStandardStreams = true

src/main/java/com/williamfiset/algorithms/datastructures/stack/ArrayStack.java

@@ -3,7 +3,9 @@
 import java.util.Arrays;
 import java.util.EmptyStackException;
 
-/** @author liujingkun */
+/**
+ * @author liujingkun
+ */
 public class ArrayStack<T> implements Stack<T> {
   private int size;
   private int capacity;

src/main/java/com/williamfiset/algorithms/datastructures/stack/Stack.java

@@ -1,6 +1,8 @@
 package com.williamfiset.algorithms.datastructures.stack;
 
-/** @author liujingkun */
+/**
+ * @author liujingkun
+ */
 public interface Stack<T> {
   // return the number of elements in the stack
   public int size();

src/main/java/com/williamfiset/algorithms/graphtheory/ConnectedComponentsDfsSolverAdjacencyList.java

@@ -19,7 +19,9 @@ public class ConnectedComponentsDfsSolverAdjacencyList {
   private boolean[] visited;
   private List<List<Integer>> graph;
 
-  /** @param graph - An undirected graph as an adjacency list. */
+  /**
+   * @param graph - An undirected graph as an adjacency list.
+   */
   public ConnectedComponentsDfsSolverAdjacencyList(List<List<Integer>> graph) {
     if (graph == null) throw new NullPointerException();
     this.n = graph.size();

src/main/java/com/williamfiset/algorithms/graphtheory/networkflow/NetworkFlowSolverBase.java

@@ -1,4 +1,6 @@
-/** @author William Fiset, william.alexandre.fiset@gmail.com */
+/**
+ * @author William Fiset, william.alexandre.fiset@gmail.com
+ */
 package com.williamfiset.algorithms.graphtheory.networkflow;
 
 import java.util.ArrayList;

src/main/java/com/williamfiset/algorithms/graphtheory/treealgorithms/LowestCommonAncestor.java

@@ -14,7 +14,7 @@ public static class TreeNode {
 
     // Useful constructor for root node.
     public TreeNode(int id) {
-      this(id, /*parent=*/ null);
+      this(id, /* parent= */ null);
     }
 
     public TreeNode(int id, TreeNode parent) {

src/main/java/com/williamfiset/algorithms/graphtheory/treealgorithms/LowestCommonAncestorEulerTour.java

@@ -94,7 +94,7 @@ public static class TreeNode {
 
     // Useful constructor for root node.
     public TreeNode(int index) {
-      this(index, /*parent=*/ null);
+      this(index, /* parent= */ null);
     }
 
     public TreeNode(int index, TreeNode parent) {
@@ -192,7 +192,7 @@ private void setup(TreeNode root) {
     last = new int[n];
 
     // Do depth first search to construct Euler tour.
-    dfs(root, /*depth=*/ 0);
+    dfs(root, /* depth= */ 0);
 
     // Initialize and build sparse table on the `nodeDepth` array which will
     // allow us to index into the `nodeOrder` array and return the LCA.

src/main/java/com/williamfiset/algorithms/graphtheory/treealgorithms/RootingTree.java

@@ -19,7 +19,7 @@ public static class TreeNode {
 
     // Useful constructor for root node.
     public TreeNode(int id) {
-      this(id, /*parent=*/ null);
+      this(id, /* parent= */ null);
     }
 
     public TreeNode(int id, TreeNode parent) {

src/main/java/com/williamfiset/algorithms/graphtheory/treealgorithms/TreeIsomorphism.java

@@ -19,7 +19,7 @@ public static class TreeNode {
 
     // Useful constructor for root node.
     public TreeNode(int id) {
-      this(id, /*parent=*/ null);
+      this(id, /* parent= */ null);
     }
 
     public TreeNode(int id, TreeNode parent) {

src/main/java/com/williamfiset/algorithms/math/NChooseRModPrime.java

@@ -1,4 +1,6 @@
-/** @author Rohit Mazumder, mazumder.rohit7@gmai.com */
+/**
+ * @author Rohit Mazumder, mazumder.rohit7@gmai.com
+ */
 package com.williamfiset.algorithms.math;
 
 import java.math.BigInteger;

src/test/java/com/williamfiset/algorithms/datastructures/balancedtree/AVLTreeTest.java

@@ -6,7 +6,6 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.TreeSet;
-
 import org.junit.jupiter.api.*;
 
 public class AVLTreeTest {

src/test/java/com/williamfiset/algorithms/datastructures/balancedtree/RedBlackTreeTest.java

@@ -4,7 +4,6 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.*;
-
 import org.junit.jupiter.api.*;
 
 public class RedBlackTreeTest {

src/test/java/com/williamfiset/algorithms/datastructures/balancedtree/TreapTreeTest.java

@@ -7,7 +7,6 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.TreeSet;
-
 import org.junit.jupiter.api.*;
 
 public class TreapTreeTest {

src/test/java/com/williamfiset/algorithms/datastructures/binarysearchtree/BinarySearchTreeTest.java

@@ -10,7 +10,6 @@
 import java.util.Deque;
 import java.util.Iterator;
 import java.util.List;
-
 import org.junit.jupiter.api.*;
 
 class TestTreeNode {
@@ -214,12 +213,14 @@ public void concurrentModificationErrorPreOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.PRE_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.add(0);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.add(0);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -233,12 +234,14 @@ public void concurrentModificationErrorInOrderOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.IN_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.add(0);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.add(0);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -252,12 +255,14 @@ public void concurrentModificationErrorPostOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.POST_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.add(0);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.add(0);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -271,12 +276,14 @@ public void concurrentModificationErrorLevelOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.LEVEL_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.add(0);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.add(0);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -290,12 +297,14 @@ public void concurrentModificationErrorRemovingPreOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.PRE_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.remove(2);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.remove(2);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -309,12 +318,14 @@ public void concurrentModificationErrorRemovingInOrderOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.IN_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.remove(2);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.remove(2);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -328,12 +339,14 @@ public void concurrentModificationErrorRemovingPostOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.POST_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.remove(2);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.remove(2);
+            iter.next();
+          }
+        });
   }
 
   @Test
@@ -347,12 +360,14 @@ public void concurrentModificationErrorRemovingLevelOrder() {
 
     Iterator<Integer> iter = bst.traverse(TreeTraversalOrder.LEVEL_ORDER);
 
-    assertThrows(ConcurrentModificationException.class, () -> {
-      while (iter.hasNext()) {
-        bst.remove(2);
-        iter.next();
-      }
-    });
+    assertThrows(
+        ConcurrentModificationException.class,
+        () -> {
+          while (iter.hasNext()) {
+            bst.remove(2);
+            iter.next();
+          }
+        });
   }
 
   @Test

src/test/java/com/williamfiset/algorithms/datastructures/binarysearchtree/SplayTreeTest.java

@@ -4,7 +4,6 @@
 
 import com.williamfiset.algorithms.datastructures.utils.TestUtils;
 import java.util.*;
-
 import org.junit.jupiter.api.Test;
 
 public class SplayTreeTest {

src/test/java/com/williamfiset/algorithms/datastructures/bloomfilter/BloomFilterTest.java

@@ -6,7 +6,6 @@
 import java.util.HashSet;
 import java.util.Random;
 import java.util.Set;
-
 import org.junit.jupiter.api.*;
 
 public class BloomFilterTest {

src/test/java/com/williamfiset/algorithms/datastructures/fibonacciheap/FibonacciHeapTest.java

@@ -10,7 +10,6 @@
 import java.util.NoSuchElementException;
 import java.util.Queue;
 import java.util.Random;
-
 import org.junit.jupiter.api.*;
 
 // Disclaimer: Based by help of