Since Java 9, we can use aList<E>.of(E… elements)static factory method to create an immutable list: @Test(expected = UnsupportedOperationException.class)publicfinalvoidgivenUsingTheJava9_whenUnmodifiableListIsCreated_thenNotModifiable(){finalList<String> list =newArrayList<>(Arrays.asList("one...
ImmutableSet<String> imSet = ImmutableSet.of("seven","lisa","seven1","lisa1");System.out.println("imSet:"+ imSet);//[seven, lisa, seven1, lisa1]ImmutableList<String> imlist = ImmutableList.copyOf(imSet);System.out.println("imlist:"+ imlist);//[seven, lisa, seven1, lisa1]Im...
Take the example ofjava.lang.Stringclass which is an immutable class. Once a String is created, there is no way we can change the content of that String. Every public API inStringclass returns a new String with the modified content. The originalStringalways remains the same. Stringstring="t...
在Java中测试不可变类(Immutable Class)时,我们需要确保类的实例在创建后不能被修改。下面是一个详细的步骤指南,包括如何创建一个不可变类、编写测试用例,并验证不可变类的行为。 1. 创建一个不可变类 首先,我们需要一个不可变类的示例。以下是一个简单的不可变类Person的实现: java public final class Person ...
* In practice, you should use the List's own iterator * object, returned by its iterator() method. */ public class MyIterator { private final List<String> list; private int index; // list[index] is the next element that will be returned // by next() // index == list.size() me...
Next, let’s wrap it up withCollections.unmodifiableSet(): Set<String> unmodifiableSet = Collections.unmodifiableSet(set); Finally, to make sure ourunmodifiableSetinstance is immutable, let’s create a simple test case: @Test(expected = UnsupportedOperationException.class) public void testUnmodifiableSet...
There is a list of rules that we need to apply to make the above class immutable. Let me first list them down: I first remove all thesettermethods to restrict the modification of fields. I will make all fieldsfinalandprivate. I will make the classfinalto restrict mutable subclasses and us...
In a typical class, this validate() method would be called anytime a user’s balance is changed. If the user makes a withdrawl, pays their debt, or transfers money from their account we would have to call the validate method. However, with an immutable class we only have to call the...
16/10/09 23:36:21 ERROR Executor: Exception in task 2.3 in stage 0.0 (TID 21) java.lang.ClassCastException: cannot assign instance of scala.collection.immutable.List$SerializationProxy to field org.apache.spark.rdd.RDD.org$apache$spark$rdd$RDD$$dependencies_ of type scala.collection.Seq in...
Immutable中的Collection是一个基类,放在后端语言Java中来说就是一个抽象类,其中定义了很多方法,提供给子类来实现。因此Collection不能直接使用其构造函数。其中它又分成了几个子类,分别是Collection.Keyed,Collection.Indexed, orCollection.Set,List/Map/Set/Stack分别都是继承他们而来。