Arrays.asList vs Collections.singletonsList about immutable.. in Java [duplicate]

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doc says Collections.singletonList is immutable so i test about Arrays.asList and Collections.singletonsList.

First Test

    List<Student> asList = Arrays.asList(new Student(10));      Student student = asList.get(0);      student.setAge(20);      System.out.println(asList); // 20        List<Student> singletonList = Collections.singletonList(new Student(10));      Student student1 = singletonList.get(0);      student1.setAge(20);      System.out.println(singletonList); // 20  

it is not immutable.

Second Test

    List<Student> asList = Arrays.asList(new Student(10));      Student student = asList.get(0);      student = null;      System.out.println(asList); // 10        List<Student> singletonList = Collections.singletonList(new Student(10));      Student student1 = singletonList.get(0);      student1 = null;      System.out.println(singletonList) ; // 10  

can not change reference.

Third Test

    List<Student> asList = Arrays.asList(new Student(10));      asList.remove(0); // UnsupportedOperationException        List<Student> singletonList = Collections.singletonList(new Student(10));      singletonList.remove(0); // UnsupportedOperationException  

so what is difference??

https://stackoverflow.com/questions/65433098/arrays-aslist-vs-collections-singletonslist-about-immutable-in-java December 24, 2020 at 09:58AM