From 8f0c540ef3ca885798fda24297cdf040fa673893 Mon Sep 17 00:00:00 2001
From: Michael Schnell <michael@fuin.org>
Date: Sun, 25 Feb 2024 17:16:56 +0100
Subject: [PATCH] Added hashcode and equals to KeyValue

---
 .../org/fuin/objects4j/core/KeyValue.java     | 55 ++++++++++++-------
 .../org/fuin/objects4j/core/KeyValueTest.java | 17 ++++++
 2 files changed, 51 insertions(+), 21 deletions(-)

diff --git a/core/src/main/java/org/fuin/objects4j/core/KeyValue.java b/core/src/main/java/org/fuin/objects4j/core/KeyValue.java
index d0dd994..73c6bb8 100644
--- a/core/src/main/java/org/fuin/objects4j/core/KeyValue.java
+++ b/core/src/main/java/org/fuin/objects4j/core/KeyValue.java
@@ -22,35 +22,41 @@
 import org.fuin.objects4j.common.ValueObject;
 
 import javax.annotation.concurrent.Immutable;
+import java.io.Serial;
+import java.io.Serializable;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 /**
- * Container for a key and a value.
+ * Container for a key and a value. Equals and hashcode are based on the key only.
  */
 @Immutable
-public final class KeyValue implements ValueObject {
+public final class KeyValue implements ValueObject, Serializable {
+
+    @Serial
+    private static final long serialVersionUID = 1000L;
 
     @TrimmedNotEmpty
-    private String key;
+    private final String key;
 
-    private Object value;
+    private final Object value;
 
     /**
      * Protected default constructor for deserialization.
      */
     protected KeyValue() {
         super();
+        this.key = null;
+        this.value = null;
     }
 
     /**
      * Constructor with key and value.
      *
-     * @param key
-     *            Key.
-     * @param value
-     *            Value.
+     * @param key   Key.
+     * @param value Value.
      */
     public KeyValue(@NotNull @TrimmedNotEmpty final String key, final Object value) {
         super();
@@ -65,7 +71,7 @@ public KeyValue(@NotNull @TrimmedNotEmpty final String key, final Object value)
      *
      * @return Key.
      */
-    public final String getKey() {
+    public String getKey() {
         return key;
     }
 
@@ -74,7 +80,7 @@ public final String getKey() {
      *
      * @return Value.
      */
-    public final Object getValue() {
+    public Object getValue() {
         return value;
     }
 
@@ -83,13 +89,26 @@ public final Object getValue() {
      *
      * @return Value or "null".
      */
-    public final String getValueString() {
+    public String getValueString() {
         if (value == null) {
             return "null";
         }
         return value.toString();
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        KeyValue keyValue = (KeyValue) o;
+        return Objects.equals(key, keyValue.key);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(key);
+    }
+
     @Override
     public String toString() {
         return "KeyValue{" +
@@ -102,11 +121,8 @@ public String toString() {
      * Replaces all variables in the format "${NAME}" with the corresponding value. NAME is the name of a key from the <code>keyValue</code>
      * array.
      *
-     * @param message
-     *            Message to replace.
-     * @param keyValue
-     *            Array of key values or {@literal null}.
-     *
+     * @param message  Message to replace.
+     * @param keyValue Array of key values or {@literal null}.
      * @return Replaced message.
      */
     public static String replace(final String message, final KeyValue... keyValue) {
@@ -143,11 +159,8 @@ private static String nullSafeAsString(final Object obj) {
     /**
      * Replaces all variables inside a string with values from a map.
      *
-     * @param str
-     *            Text with variables (Format: ${key} ) - May be {@literal null} or empty.
-     * @param vars
-     *            Map with key/values (both of type <code>String</code> - Cannot be {@literal null}.
-     *
+     * @param str  Text with variables (Format: ${key} ) - May be {@literal null} or empty.
+     * @param vars Map with key/values (both of type <code>String</code> - Cannot be {@literal null}.
      * @return String with replaced variables. Unknown variables will remain unchanged.
      */
     public static String replaceVars(final String str, final Map<String, String> vars) {
diff --git a/core/src/test/java/org/fuin/objects4j/core/KeyValueTest.java b/core/src/test/java/org/fuin/objects4j/core/KeyValueTest.java
index f443b12..e83228e 100644
--- a/core/src/test/java/org/fuin/objects4j/core/KeyValueTest.java
+++ b/core/src/test/java/org/fuin/objects4j/core/KeyValueTest.java
@@ -17,7 +17,9 @@
  */
 package org.fuin.objects4j.core;
 
+import nl.jqno.equalsverifier.EqualsVerifier;
 import org.fuin.objects4j.common.ConstraintViolationException;
+import org.fuin.utils4j.Utils4J;
 import org.junit.jupiter.api.Test;
 
 import java.util.ArrayList;
@@ -54,6 +56,21 @@ void testCreateInvalidKey() {
 
     }
 
+    @Test
+    void testEqualHashCode() {
+        EqualsVerifier.forClass(KeyValue.class).withIgnoredFields("value").verify();
+    }
+
+    @Test
+    void testSerializeDeserialize() {
+        final KeyValue original = new KeyValue("one", 1);
+        final KeyValue copy = Utils4J.deserialize(Utils4J.serialize(original));
+        assertThat(copy).isEqualTo(original);
+        assertThat(copy.getKey()).isEqualTo(original.getKey());
+        assertThat(copy.getValue()).isEqualTo(original.getValue());
+        assertThat(copy.getValueString()).isEqualTo("1");
+    }
+
     @Test
     void testReplaceVarsNull() {
         assertThat(KeyValue.replace(null)).isNull();