1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
import org.checkerframework.checker.nullness.qual.*;
// This is the example from manual section:
// "Generics (parametric polymorphism or type polymorphism)"
// whose source code is ../../../docs/manual/advanced-features.tex
class GenericsExampleMin {
class MyList1<@Nullable T> {
T t;
@Nullable T nble;
@NonNull T nn;
public MyList1(T t, @Nullable T nble, @NonNull T nn) {
this.t = t;
this.nble = nble;
this.nn = nn;
this.t = this.nble;
}
T get(int i) {
return t;
}
// This method works.
// Note that it fails to work if it is moved after m2() in the syntax tree.
// TODO: the above comment seems out-of-date, as method
// m3 below works.
void m1() {
t = this.get(0);
nble = this.get(0);
}
// When the assignment to nn is added, the assignments to t and nble also fail, which is
// unexpected.
void m2() {
// :: error: (assignment.type.incompatible)
nn = null;
t = this.get(0);
nble = this.get(0);
}
void m3() {
t = this.get(0);
nble = this.get(0);
}
}
class MyList2<@NonNull T> {
T t;
@Nullable T nble;
public MyList2(T t, @Nullable T nble) {
// :: error: (assignment.type.incompatible)
this.t = this.nble; // error
// :: error: (assignment.type.incompatible)
this.t = nble; // error
}
}
class MyList3<T extends @Nullable Object> {
T t;
@Nullable T nble;
@NonNull T nn;
public MyList3(T t, @Nullable T nble, @NonNull T nn) {
// :: error: (assignment.type.incompatible)
this.t = nble;
this.t = nn;
// :: error: (assignment.type.incompatible)
this.nn = t;
// :: error: (assignment.type.incompatible)
this.nn = nble;
this.nn = nn;
}
}
class MyList4<T extends @NonNull Object> {
T t;
@Nullable T nble;
@NonNull T nn;
public MyList4(T t, @Nullable T nble, @NonNull T nn) {
// :: error: (assignment.type.incompatible)
this.t = nble;
this.t = nn;
this.nn = t;
// :: error: (assignment.type.incompatible)
this.nn = nble;
this.nn = nn;
this.nn = t;
this.nble = t;
}
}
}
|
