diff --git a/week_04/42/CopyOnWriteArrayList.xmind b/week_04/42/CopyOnWriteArrayList.xmind
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diff --git a/week_04/42/CopyOnWriteArrayListTest.java b/week_04/42/CopyOnWriteArrayListTest.java
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+package com.jdk.week4;
+
+import java.util.Objects;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+/**
+ * Copyright
+ *
+ * @author conanju
+ * @since 2020/1/5 11:19
+ */
+public class CopyOnWriteArrayListTest {
+    public static void main(String[] args) {
+        Person person = new Person(10, "conan", 20.3);
+        Person person1 = new Person(20, "jmas", 30.3);
+        Person person2 = new Person(10, "conan", 20.3);
+        System.out.println(person == person1);
+        Person[] people = {person, person1, person2};
+        CopyOnWriteArrayList arrayList = new CopyOnWriteArrayList(people);
+        System.out.println(arrayList.contains(person));
+
+        arrayList.remove(1);
+
+    }
+}
+
+class Person {
+    int age;
+    String name;
+    double salary;
+
+    public Person(int age, String name, double salary) {
+        this.age = age;
+        this.name = name;
+        this.salary = salary;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public double getSalary() {
+        return salary;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Person person = (Person) o;
+        return age == person.age &&
+                Double.compare(person.salary, salary) == 0 &&
+                Objects.equals(name, person.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(age, name, salary);
+    }
+
+    public void setSalary(double salary) {
+        this.salary = salary;
+    }
+}