如何遍历数组并找到最大值：Java

Question

在 Bellow 代码中，我应该找到与最大数字相关的月份。

波纹管是我试过的。 但是我相信有一种更简洁的方式来写这个。 我怎样才能做到这一点？

public class HelloWorld{

static int[] array = {3,6,7,3,2,30,9,13,12,1,2,1};
static String[] month = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

static int greatestVal = 0;
static int greatestVal2 = 0;
static String monthChosen = "";

int integer = 0;
static int num = 0;

     public static void main(String []args){
            int number = -1;
            for (int i = 0; i<=11; i++) {
                int currentValue = array[i];
                number += 1;
                //System.out.println(currentValue);
                for (int index = 0; index <=11; index++) {
                    if (currentValue > array[index]) {
                        greatestVal = currentValue;
                        // System.out.println(currentValue +">"+ array[index]);
                        if (greatestVal > greatestVal2) {
                            greatestVal2 = greatestVal;
                            monthChosen = month[number];
                        }
                    } else {
                        // System.out.print("Hgfhdssdgfadkhfdshkjhads");
                    }
                }
        }
            System.out.println(greatestVal2 + " greatest month is: " + monthChosen);
    }
}

Answer 1

使用流：

static int[] array = {3,6,7,3,2,30,9,13,12,1,2,1};
static String[] month = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

public static void main(String[] args) {
    int index = IntStream.range(0, array.length)
            .reduce(0, (a, b) -> array[a] >= array[b] ? a : b);
    System.out.println(array[index] + " greatest month is: " + month[index]);
}

Answer 2

您实际上并不需要为每次迭代跟踪所选月份。 假设月份通过索引与数组元素相关，您只需要找出最大元素的索引 - 您甚至不需要跟踪最大值：

public class HelloWorld {
    static int[] array = {3, 6, 7, 3, 2, 30, 9, 13, 12, 1, 2, 1};
    static String[] month = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

    public static void main(String[] args) {
        int index = 0;
        for (int i = 1; i < array.length; i++)
            if (array[index] < array[i])
                index = i;
        System.out.println(array[index] + " greatest month is: " + month[index]);
    }
}

Answer 3

如果您可以使用Map那么它非常简单。 创建一个HashMap<String, Integer> ，其中key是月份， value是计数。

然后，您可以遍历此映射并找到值最大的键值对。

解决方案 ：

    Map<String, Integer> monthMap = new HashMap<>();
    // initializing the map
    for (int i = 0; i < 12; i++)
        monthMap.put(month[i], array[i]);

    // finding <k, v> pair with highest entry
    Entry<String, Integer> entry = monthMap.entrySet().stream()
             .max(Map.Entry.comparingByValue(Comparator.comparingInt(i -> i.intValue())))
             .get();

Answer 4

仅使用您的 2 个阵列的简化解决方案...

    int max = Arrays.stream(array).max().getAsInt();
    int index = 0;
    for (int i = 0; i < array.length; i++) {
        if (array[i] == max) {
            index = i;
        }
    }
    System.out.println(array[index] + " greatest month is: " + month[index]);

Answer 5

   public static void main(String []args){
        Integer[] array = {3,6,7,3,2,30,9,13,12,1,2,1};
        String[] month = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

        Integer[] copyArr = array.clone();
        Arrays.sort(copyArr);
        int largestNum = copyArr[copyArr.length-1];
        int index = Arrays.binarySearch(array, largestNum);
        System.out.println(month[index]);
     }

输出 -> 六月

Answer 6

在 Java 中，我们有枚举，您可以在其中拥有常量和与之关联的值。 参考https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html

使用该方法，您可以定义一个枚举，其中名称为月份，值可以与它们相关联。

现在在任何其他方法中，您可以继续迭代枚举值，然后找到最大值。 因此，假设 Months 是枚举的名称，那么您可以for-each使用一个简单的for-each循环：

for (Months months:Months.values()){
  //logic for comparison.find the maximum
}

注意：ENUMS 通常用于常量。所以不确定所描述的问题是否总是每个月都有常量值，或者它可能会有所不同。如果它有所不同，那么您可以按照已经给出的答案中的描述使用streams或Maps 。