Given list of strings like this:
"Y:Yes",
"N:No",
"A:Apple"
I have something like
Map updated = values.stream().map(v -> v.split(":")).collect(Collectors.toMap(v1 -> v1[0],v1->v1.length>1?v1[1]:v1[0]));
But this gives me map as:
{
"Y":"Yes",
"N":"No",
"A":"Apple"
}
How can I get a list of maps as such:
[
{
name:"Y",
display:"Yes"
},
{
name:"N",
display:"No"
},
{
name:"A",
display:"Apple"
}
]
If you are using Java 9, you can use the new immutable map static factory methods, as follows:
List<Map<String, String>> updated = values.stream()
.map(v -> v.split(":"))
.map(a -> Map.of("name", a[0], "display", a[1]))
.collect(Collectors.toList());
As you want to get a List, not a map, your last function call cannot be Collectors.toMap, needs to be Collectors.toList. Now, each invocation to the map method should generate a new Map, so something like this would do:
List updated = values.stream()
.map(v -> {
String[] parts = v.split(":");
Map<String, String> map = new HashMap<>();
map.put("name", parts[0]);
map.put("display", parts[1]);
return map;
)
.collect(Collectors.toList());
Some people would prefer:
List updated = values.stream()
.map(v -> {
String[] parts = v.split(":");
return new HashMap<>() {{
put("name", parts[0]);
put("display", parts[1]);
}};
)
.collect(Collectors.toList());
which creates an extra helper class. Or if you can use Guava:
List updated = values.stream()
.map(v -> {
String[] parts = v.split(":");
return ImmutableMap.of("name", parts[0], "display", parts[1]);
)
.collect(Collectors.toList());
BTW: In the examples I used Listbut the complete type of what you describe would be List<Map<String, String>>.
You can use following if you're still using Java8, if you happen to use Java9 then have a look at Federicos answer:
final List<Map<String,String>> updated = values.stream()
.map(v -> v.split(":"))
.map(arr -> {
Map<String, String> map = new HashMap<>();
map.put("name", arr[0]);
map.put("display", arr[1]);
return map;
})
.collect(Collectors.toList());
List<>and outputList<>types and what's the error with your piece of code as well.