I want to remove some elements from my list of objects based on certain conditions. Can I do it with Java 8 streams?
public static void doAction(List<Hunt> list) {
for (ListIterator<Hunt> iter = list.listIterator(); iter.hasNext(); ) {
Hunt h = iter.next();
if (h.getTokens().contains("INC")) {
String[] tags = h.getTokens().split(";");
for (String tag : tags) {
if (tag.contains("INC")) {
String value = tag.substring(tag.length() - 1);
if ("N".equals(value)) {
if (flag) {
if (!h.getPropertyA().equals(anotherObject.getPropertyAValue())) {
iter.remove();
}
}
else {
if (!h.getPropertyB().equals(anotherObject.getPropertyBValue)) {
iter.remove();
}
}
}
}
}
}
}
}
I think you can do it with stream by using removeIf
and some condition :
list.removeIf(h -> h.getTokens().contains("INC") &&
Arrays.stream(h.getTokens().split(";"))
.filter(tag -> tag.contains("INC"))
.map(tag -> tag.substring(tag.length() - 1))
.filter("N"::equals)
.anyMatch(v ->
(flag && !h.getPropertyA().equals(anotherObject.getPropertyAValue())) ||
(!flag && !h.getPropertyB().equals(anotherObject.getPropertyBValue()))));
Or you can separated the condition in a separated method, for example :
static void doAction(List<Hunt> list) {
list.removeIf(MyClass::isCorrect);
}
private static boolean isCorrect(Hunt h) {
return h.getTokens().contains("INC") &&
Arrays.stream(h.getTokens().split(";"))
.filter(tag -> tag.contains("INC"))
.map(tag -> tag.substring(tag.length() - 1))
.filter("N"::equals)
.anyMatch(v ->
(flag && !h.getPropertyA().equals(anotherObject.getPropertyAValue())) ||
(!flag && !h.getPropertyB().equals(anotherObject.getPropertyBValue())));
}
Or as @Tom Hawtin - tackline suggest, you can use :
static void doAction(List<Hunt> list) {
list.removeIf(h -> h.getTokens().contains("INC") &&
Arrays.stream(h.getTokens().split(";"))
.anyMatch(tag -> tag.contains("INC") && tag.endsWith("N")
&& !(flag ? h.getPropertyA().equals(anotherObject.getPropertyAValue())
: h.getPropertyB().equals(anotherObject.getPropertyBValue()))));
}
IMO stream API wont help you in this case! And this style of code is more readable in compared with stream based version. however I think you can make improvement by changing a bit.
Remove temporary variables such as String[] tags = h.getTokens().split(";");
and String value = tag.substring(tag.length() - 1);
Combine some conditions with together.
Use tag.charAt(tag.length() - 1)
instead of tag.substring(tag.length() - 1);
public static void doAction(List<Hunt> list) { for (ListIterator<Hunt> iter = list.listIterator(); iter.hasNext(); ) { Hunt h = iter.next(); if (h.getTokens().contains("INC")) { for (String tag : h.getTokens().split(";")) { if (tag.contains("INC") && tag.charAt(tag.length() - 1) == 'N') { if (flag) { if (!h.getPropertyA().equals(anotherObject.getPropertyAValue())) { iter.remove(); } } else { if (!h.getPropertyB().equals(anotherObject.getPropertyBValue)) { iter.remove(); } } } } } } }
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