Comparator.nullsLast does not avoid NullPointerException
4
I want to sort a list of objects by one of nullable fields.
In order to avoid NullPointerexception I use Comparator.nullsLast. But the exception still occurs:
public class Test {
public static void main(String args) {
List<Bean> l = new ArrayList<>();
for (int i=0;i<5;i++) {
Bean b = new Bean("name_"+i,i);
l.add(b);
}
l.get(2).setVal(null);
System.out.println(l);
Collections.sort(l, Comparator.nullsLast(Comparator.comparing(Bean::getVal)));
System.out.println(l);
}
static class Bean{
String name;
Integer val;
// omit getters & setters & constructor
}
}
How can I sort this kind of list?
java collections java-8 java-stream comparator
edited Nov 15 '18 at 10:37
ETO
1,976422
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
add a comment |
4
I want to sort a list of objects by one of nullable fields.
In order to avoid NullPointerexception I use Comparator.nullsLast. But the exception still occurs:
public class Test {
public static void main(String args) {
List<Bean> l = new ArrayList<>();
for (int i=0;i<5;i++) {
Bean b = new Bean("name_"+i,i);
l.add(b);
}
l.get(2).setVal(null);
System.out.println(l);
Collections.sort(l, Comparator.nullsLast(Comparator.comparing(Bean::getVal)));
System.out.println(l);
}
static class Bean{
String name;
Integer val;
// omit getters & setters & constructor
}
}
How can I sort this kind of list?
java collections java-8 java-stream comparator
edited Nov 15 '18 at 10:37
ETO
1,976422
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
@rellocswood Please, post your solution as an answer instead of editing the question.
– Tomasz Linkowski
Nov 15 '18 at 7:39
add a comment |
4
4
4
I want to sort a list of objects by one of nullable fields.
In order to avoid NullPointerexception I use Comparator.nullsLast. But the exception still occurs:
public class Test {
public static void main(String args) {
List<Bean> l = new ArrayList<>();
for (int i=0;i<5;i++) {
Bean b = new Bean("name_"+i,i);
l.add(b);
}
l.get(2).setVal(null);
System.out.println(l);
Collections.sort(l, Comparator.nullsLast(Comparator.comparing(Bean::getVal)));
System.out.println(l);
}
static class Bean{
String name;
Integer val;
// omit getters & setters & constructor
}
}
How can I sort this kind of list?
java collections java-8 java-stream comparator
edited Nov 15 '18 at 10:37
ETO
1,976422
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
I want to sort a list of objects by one of nullable fields.
In order to avoid NullPointerexception I use Comparator.nullsLast. But the exception still occurs:
public class Test {
public static void main(String args) {
List<Bean> l = new ArrayList<>();
for (int i=0;i<5;i++) {
Bean b = new Bean("name_"+i,i);
l.add(b);
}
l.get(2).setVal(null);
System.out.println(l);
Collections.sort(l, Comparator.nullsLast(Comparator.comparing(Bean::getVal)));
System.out.println(l);
}
static class Bean{
String name;
Integer val;
// omit getters & setters & constructor
}
}
How can I sort this kind of list?
java collections java-8 java-stream comparator
java collections java-8 java-stream comparator
edited Nov 15 '18 at 10:37
ETO
1,976422
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
edited Nov 15 '18 at 10:37
ETO
1,976422
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
edited Nov 15 '18 at 10:37
ETO
1,976422
edited Nov 15 '18 at 10:37
ETO
1,976422
edited Nov 15 '18 at 10:37
ETO
1,976422
1,976422
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
asked Nov 15 '18 at 7:15
rellocs woodrellocs wood
252214
252214
@rellocswood Please, post your solution as an answer instead of editing the question.
– Tomasz Linkowski
Nov 15 '18 at 7:39
add a comment |
@rellocswood Please, post your solution as an answer instead of editing the question.
– Tomasz Linkowski
Nov 15 '18 at 7:39
@rellocswood Please, post your solution as an answer instead of editing the question.
– Tomasz Linkowski
Nov 15 '18 at 7:39
@rellocswood Please, post your solution as an answer instead of editing the question.
– Tomasz Linkowski
Nov 15 '18 at 7:39
add a comment |
2 Answers
2
active
oldest
votes
6
You should use Comparator.nullsLast twice:
list.sort(nullsLast(comparing(Bean::getVal, nullsLast(naturalOrder()))));
- First
nullsLastwill handle the cases when theBeanobjects are null. - Second
nullsLastwill handle the cases when the return value ofBean::getValis null.
In case you're sure there aren't any null values in your list then you can omit the first nullsLast (as noted by @Holger) :
list.sort(comparing(Bean::getVal, nullsLast(naturalOrder())));
answered Nov 15 '18 at 8:31
ETOETO
1,976422
1
Or omit the outernullsLastif the beans are nevernull, i.e. only the property values might benull.
– Holger
Nov 15 '18 at 8:40
add a comment |
2
You can possibly use :
Collections.sort(l, Comparator.comparing(Bean::getVal,
Comparator.nullsLast(Comparator.naturalOrder())));
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
6
You should use Comparator.nullsLast twice:
list.sort(nullsLast(comparing(Bean::getVal, nullsLast(naturalOrder()))));
- First
nullsLastwill handle the cases when theBeanobjects are null. - Second
nullsLastwill handle the cases when the return value ofBean::getValis null.
In case you're sure there aren't any null values in your list then you can omit the first nullsLast (as noted by @Holger) :
list.sort(comparing(Bean::getVal, nullsLast(naturalOrder())));
answered Nov 15 '18 at 8:31
ETOETO
1,976422
1
Or omit the outernullsLastif the beans are nevernull, i.e. only the property values might benull.
– Holger
Nov 15 '18 at 8:40
add a comment |
6
You should use Comparator.nullsLast twice:
list.sort(nullsLast(comparing(Bean::getVal, nullsLast(naturalOrder()))));
- First
nullsLastwill handle the cases when theBeanobjects are null. - Second
nullsLastwill handle the cases when the return value ofBean::getValis null.
In case you're sure there aren't any null values in your list then you can omit the first nullsLast (as noted by @Holger) :
list.sort(comparing(Bean::getVal, nullsLast(naturalOrder())));
answered Nov 15 '18 at 8:31
ETOETO
1,976422
1
Or omit the outernullsLastif the beans are nevernull, i.e. only the property values might benull.
– Holger
Nov 15 '18 at 8:40
add a comment |
6
6
6
You should use Comparator.nullsLast twice:
list.sort(nullsLast(comparing(Bean::getVal, nullsLast(naturalOrder()))));
- First
nullsLastwill handle the cases when theBeanobjects are null. - Second
nullsLastwill handle the cases when the return value ofBean::getValis null.
In case you're sure there aren't any null values in your list then you can omit the first nullsLast (as noted by @Holger) :
list.sort(comparing(Bean::getVal, nullsLast(naturalOrder())));
answered Nov 15 '18 at 8:31
ETOETO
1,976422
You should use Comparator.nullsLast twice:
list.sort(nullsLast(comparing(Bean::getVal, nullsLast(naturalOrder()))));
- First
nullsLastwill handle the cases when theBeanobjects are null. - Second
nullsLastwill handle the cases when the return value ofBean::getValis null.
In case you're sure there aren't any null values in your list then you can omit the first nullsLast (as noted by @Holger) :
list.sort(comparing(Bean::getVal, nullsLast(naturalOrder())));
answered Nov 15 '18 at 8:31
ETOETO
1,976422
edited Nov 15 '18 at 16:52
answered Nov 15 '18 at 8:31
ETOETO
1,976422
answered Nov 15 '18 at 8:31
ETOETO
1,976422
answered Nov 15 '18 at 8:31
ETOETO
1,976422
1,976422
1
Or omit the outernullsLastif the beans are nevernull, i.e. only the property values might benull.
– Holger
Nov 15 '18 at 8:40
add a comment |
1
Or omit the outernullsLastif the beans are nevernull, i.e. only the property values might benull.
– Holger
Nov 15 '18 at 8:40
1
1
Or omit the outer
nullsLast if the beans are never null, i.e. only the property values might be null.– Holger
Nov 15 '18 at 8:40
Or omit the outer
nullsLast if the beans are never null, i.e. only the property values might be null.– Holger
Nov 15 '18 at 8:40
add a comment |
2
You can possibly use :
Collections.sort(l, Comparator.comparing(Bean::getVal,
Comparator.nullsLast(Comparator.naturalOrder())));
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
add a comment |
2
You can possibly use :
Collections.sort(l, Comparator.comparing(Bean::getVal,
Comparator.nullsLast(Comparator.naturalOrder())));
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
add a comment |
2
2
2
You can possibly use :
Collections.sort(l, Comparator.comparing(Bean::getVal,
Comparator.nullsLast(Comparator.naturalOrder())));
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
You can possibly use :
Collections.sort(l, Comparator.comparing(Bean::getVal,
Comparator.nullsLast(Comparator.naturalOrder())));
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
answered Nov 15 '18 at 7:28
nullpointernullpointer
44.1k1095182
44.1k1095182
add a comment |
add a comment |
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@rellocswood Please, post your solution as an answer instead of editing the question.
– Tomasz Linkowski
Nov 15 '18 at 7:39