Sample code for article - JIRA: (BAEL-1079) Java 8 Streams distinctBy() some property(+ external tools)

2017-08-15 23:48:47 -03:00
parent bcc122b724
commit 7ec1db1be2
8 changed files with 260 additions and 8 deletions
@@ -0,0 +1,15 @@
+package com.baeldung.distinct;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+public class DistinctWithJavaFunction {
+
+    public static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
+        Map<Object, Boolean> seen = new ConcurrentHashMap<>();
+        return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
+    }
+
+}
@@ -0,0 +1,65 @@
+package com.baeldung.distinct;
+
+public class Person {
+    int age;
+    String name;
+    String email;
+
+    public Person(int age, String name, String email) {
+        super();
+        this.age = age;
+        this.name = name;
+        this.email = email;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Person [age=");
+        builder.append(age);
+        builder.append(", name=");
+        builder.append(name);
+        builder.append(", email=");
+        builder.append(email);
+        builder.append("]");
+        return builder.toString();
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((email == null) ? 0 : email.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Person other = (Person) obj;
+        if (email == null) {
+            if (other.email != null)
+                return false;
+        } else if (!email.equals(other.email))
+            return false;
+        return true;
+    }
+
+}