@umair.ali 和 @Casper 给出的答案很好,将您的数组转换为 Maps 是要走的路。
我建议使用TreeMap
(或其他SortMap
接口实现)。TreeMap 默认按升序对其键进行排序。这样一来,如果您真的想要节省大量的费用,您就不必在处理后进行任何尴尬的地图排序。
这是完整的示例:
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;
public class SavingsApp {
public Map<Integer, Integer> arraysToMap(int[] years, int[] money) {
Map<Integer, Integer> newMap = new HashMap<Integer, Integer>();
if (years == null || money == null || years.length != money.length) {
throw new IllegalArgumentException();
}
for (int i=0; i< years.length; i++ ) {
newMap.put(years[i], money[i]);
}
return newMap;
}
public Map<Integer, Integer> calculateSavings(Map<Integer, Integer> earningsMap, Map<Integer, Integer>expensesMap) {
Map<Integer, Integer> savingsMap = new TreeMap<Integer, Integer>();
savingsMap.putAll(earningsMap);
for (Entry<Integer, Integer> expensePerYear : expensesMap.entrySet()) {
Integer year = expensePerYear.getKey();
Integer expense = expensePerYear.getValue();
Integer earning = savingsMap.get(year);
if (earning == null) {
earning = 0;
}
savingsMap.put(year, earning-expense);
}
return savingsMap;
}
public static void main(String[] args) {
int[] earningYear = {2012,2013,2014};
int[] earningAmount = {100,150,120};
int[] expenseYear = {2012,2014};
int[] expenseAmount = {50,30};
SavingsApp app = new SavingsApp();
// convert arrays to maps
Map<Integer, Integer> earningsMap = app.arraysToMap(earningYear, earningAmount);
Map<Integer, Integer> expensesMap = app.arraysToMap(expenseYear, expenseAmount);
// compute savings per year
Map<Integer, Integer> savingsMap = app.calculateSavings(earningsMap, expensesMap);
// convert result map to array
List<Integer> savingsList = new ArrayList<Integer>(savingsMap.values());
Integer[] savingsArray = new Integer[savingsList.size()];
savingsList.toArray(savingsArray);
}
}
需要注意的一件事是,savingsArray
它将是Integer[]
type 而不是int[]
.