Junit test for method java

How can i write a JUnit test for this method

public E get(int index) { if(index< 0 || index>=array.length) throw new IndexOutOfBoundsException(); return array[index]; }

i tried this test but it return NullPointerException

@Test
public void test() {
    int expected_value = 7;
    int actual_value = arr.get(7);
    assertEquals("Error failed:",expected_value, actual_value);
}