[英]How to sort items of List in ascending order of function in java?
Input:输入:
["-5", "-12", "0", "20", "9", "-20", "37"]
Output: Output:
["0", "-5", "9", "-12", "-20", "20", "37"]
What logic should I use in order to get minimum of function result?我应该使用什么逻辑来获得最少 function 结果?
I have a class with function which compares 2 items (int) and returns min of them:我有一个 class 和 function,它比较 2 个项目 (int) 并返回其中的最小值:
class ListComparator implements Comparator<String> {
@Override
public int compare(String a, String b) {
int intA = Integer.parseInt(a);
int intB = Integer.parseInt(b);
int calculatedA = calc(intA);
int calculatedB = calc(intB);
return (calculatedA < calculatedB) ? intA : intB;
}
private int calc(int x) {
double form = Math.pow(5*x, 2) + 3;
int result = (int) form;
return result;
}
}
Looks like you need to sort the array or list based on the modulus (the function Math.abs()).看起来您需要根据模数(function Math.abs())对数组或列表进行排序。
String[] ss = {"-5", "-12", "0", "20", "9", "-20", "37"};
List<String> strings = Arrays.asList(ss);
Collections.sort(strings, new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
int intA = Integer.parseInt(o1);
int intB = Integer.parseInt(o2);
return Integer.compare(Math.abs(intA), Math.abs(intB));
}
});
I resolved this by returning我通过返回解决了这个问题
return calculatedA > calculatedB ? -1 : (calculatedA < calculatedB) ? 1 : 0;
and after I used Collections.sort():在我使用 Collections.sort() 之后:
public void sort(List<String> sourceList) {
Collections.sort(sourceList, new ListComparator());
Collections.reverse(sourceList);
}
I tried to use this in order to get it in ascending order but it can't help:我试图使用它来按升序排列它,但它无济于事:
return calculatedA > calculatedB ? 1 : (calculatedA < calculatedB) ? -1 : 0;
Any idea how to get it in ascending order, so that I don't use Collections.reverse(sourceList);
知道如何按升序获取它,这样我就不会使用
Collections.reverse(sourceList);
? ?
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