为什么我的变量不指向同一数组？

Question

I have two classes. One that has the array ( ArrayStorage ) and the other ( ArrayConsumer ) has just a variable that will act as a simple reference to an array.

I add a new element to the array using $my_array . Then I check to see if the new element is visible in the $obtained_array . But the test fails because it cannot find the new element. They act like they were different arrays. Shouldn't they point to the same array?

public function testArrayMadness() {
        $arrayStorage = new ArrayStorage();
        $my_array = $arrayStorage->getArray();

        $arrayConsumer = new ArrayConsumer($my_array);
        $obtained_array = $arrayConsumer->getArray();

        $my_array[3]='c';
        $this->assertContains('c', $obtained_array);
    }
}
class ArrayStorage {
    private $my_array=[1=>'a',2=>'b'];
    function getArray() { return $this->my_array; }
}
class ArrayConsumer {
    private $obtained_array;
    function __construct($array) { $this->obtained_array=$array; }
    function getArray() { return $this->obtained_array; }
}

Update: I did the same on test in Java, it gives me an indexOutOfBoundsException. Does that mean both php and java works the same way in this aspect or is there something wrong with my code?

@Test
    public void testArrayMadness() {
        ArrayStorage arrayStorage = new ArrayStorage();
        List<String> my_list = arrayStorage.getList();

        ArrayConsumer arrayConsumer = new ArrayConsumer(my_list);
        List<String> obtained_array = arrayConsumer.getList();

        my_list.add("c");
        assertEquals("c", obtained_array.get(3));
    }
}

class ArrayStorage {
    private List<String> my_list;
    public ArrayStorage() {
        my_list = new ArrayList<>();
        my_list.add("a");
        my_list.add("b");
    }
    public List<String> getList() { return my_list; }
}
class ArrayConsumer {
    private List<String> obtained_list;
    public ArrayConsumer(List<String> list) {
        this.obtained_list = list;
    }
    public List<String> getList() { return this.obtained_list; }
}

Answer 1

PHP arrays are not objects, they are assigned by value:

$a = [1,2,3];
$b = $a;
$b[2] = 99;

print_r($b); // 1,2,99
print_r($a); // 1,2,3

A workaround is to use reference signs & (a bad idea generally) or ArrayObject s:

$a = new ArrayObject([1,2,3]);
$b = $a;
$b[2] = 99;

print_r($b); // 1,2,99
print_r($a); // 1,2,99

Answer 2

使用＆运算符返回引用数组，例如return &$this->my_array;