Question

我是ArrayLists，数据包括2015年，2016年和2017年的几个月。

数据分组为 - 2015年，月份为05至12 - 2016年，月份从01到12 - 2017年，01至06月 - 月份依次为：

 [05, 05, 05, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 07, 07, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 06, 07, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 08, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 09, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 02, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 03, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 04, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05, 05]

我想做的是：在阵列的连续单元格中重复计算月数。例如，05个月重复3次，第6个月重复25次，依此类推。但它给了我以下错误：

java.lang.IndexOutOfBoundsException: Index: 534, Size: 534
Execution Completed
    at java.util.ArrayList.rangeCheck(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at yearandmonth.task(yearandmonth.java:84)

这是我的方法

int counter = 1;
                    ArrayList<Integer> monthCounterArray = new ArrayList<Integer>();
                    for(int mn = 0; mn <= monitoringMonthArray.size(); mn++){
                        if(monitoringMonthArray.get(mn).equals(monitoringMonthArray.get(mn + 1))){
                            counter++;
                        }
                        else {
                            System.out.println("Month " + monitoringMonthArray.get(mn)+ " Repeated " + counter);
                            monthCounterArray.add(counter);
                            counter = 1;
                        }
                    }

在我的案例中，BTW monitoningMonthArray大小为534

希望我提供了足够的信息

提前致谢

Answer 1

在for循环检查mn <= monitoringMonthArray.size()中，您的情况mn等于列表的大小。 java中的List（和数组）从0索引到size - 1。

因此，如果您有size==1的列表，则调用get(1)会尝试获取第二个元素。

另一件事是monitoringMonthArray.get(mn + 1)也可能超出你的规模。

你的条件应该是：

for(int mn = 0; mn < monitoringMonthArray.size() - 1; mn++)

Answer 2

这种情况没有意义：

 for(int mn = 0; mn <= monitoringMonthArray.size(); mn++){

monitoringMonthArray为ArrayList，get(int)为参数，List的大小超出ArrayList的范围。

所以你在循环中写道：

monitoringMonthArray.get(mn)

你必须以抛出的IndexOutOfBoundsException完成。

此外，循环体中的这个条件：

if(monitoringMonthArray.get(mn).equals(monitoringMonthArray.get(mn + 1))){

要求你最多迭代，直到最后一个元素出于同样的原因：

所以循环条件应该是：

 for(int mn = 0; mn < monitoringMonthArray.size()-1; mn++){

Answer 3

create()这将迭代大小+ 1次。

(int mn = 0; mn <= monitoringMonthArray.size(); mn++)

迭代大小时间，

但是由于您正在访问(int mn = 0; mn < monitoringMonthArray.size(); mn++)项，因此您应该循环mn +1次。

size -1

这应该有效。

Answer 4

如果我的问题是正确的，这是解决方案：

public static void main(String[] args) {
    List<String> monthCounterArray = Arrays.asList(new String[] { "05", "05", "05", "06", "06", "06", "06", "06", "06", "06", "06", 
        ... <your array> 
    "05", "05" });

    List<String> monthCounterArray_1 = Arrays.asList(new String[]{ "05", "05", "05", "06", "06", "06", "07", "07", "08", "09", "09", "10", "10",
            "11", "12", "12", "12", "01", "01", "01", "01", "01", "02", "03", "04", "04", "04", "04", "04", "05",
            "05", "05", "05", "06", "07", "08", "09", "10", "11", "12", "01", "01", "01", "01", "01"});

    List<String> monthCounterArray_2 = Arrays.asList(new String[] {});

    List<Integer> output = countOccurences(monthCounterArray);
    List<Integer> output_1 = countOccurences(monthCounterArray_1);
    List<Integer> output_2 = countOccurences(monthCounterArray_2);

    System.out.println(Arrays.toString(output.toArray()));
    System.out.println(Arrays.toString(output_1.toArray()));
    System.out.println(Arrays.toString(output_2.toArray()));
}

private static List<Integer> countOccurences(List<String> input) {
    List<Integer> output = new ArrayList<>();
    String previousValue = "-1";
    int k = 0;

    for (String fromInput : input) {
        if (previousValue.equals("-1")) {
            output.add(k, 1);
            previousValue = fromInput;
        } else if (previousValue.equalsIgnoreCase(fromInput)) {
            output.set(k, output.get(k) + 1);
        } else {
            if (k != 0) {
                output.set(k, output.get(k) + 1);
            }
            previousValue = "-1";
            k++;
        }
    }
    return output;
}

输出：

[3, 25, 2, 15, 25, 25, 25, 25, 21, 21, 25, 25, 25, 15, 26, 25, 25, 25, 25, 21, 21, 25, 25, 24]
[3, 3, 2, 3, 2, 4, 5, 2, 5, 4, 2, 2, 2, 5]
[]

ArrayList元素计数

4 个答案: