Question

void displayFeedback(){
    Map<String, Integer> maths = new HashMap<String, Integer>();
    maths.put("Nirmala", 70);
    maths.put("Subaksha", 80);
    Map<String, Integer> english = new HashMap<String, Integer>();
    english.put("Nirmala", 75);
    english.put("Subaksha", 60);
    //same staffs taking two different subjects maths and english 
    //values taken as feedback for each subject
    // i need to compare both subject feedback and print only max as o/p
    System.out.println(maths);
    System.out.println(maths.entrySet());
    //maths.
    //maths.entrySet();
    //Collections.max(coll, comp)
    Map<String, Integer> top = new HashMap<String, Integer>();
    System.out.println(maths.size());
    for (Map.Entry<String, Integer> math: maths.entrySet()){
        for (Map.Entry<String, Integer> eng: english.entrySet()){   
        //for(int i = 0;i<maths.size();i++){
            //math.comparingByValue()
            System.out.println(math.getValue()+" "+eng.getValue());
            //Collections.max(math.getValue(), eng.getValue());
        if(math.getValue() <= eng.getValue()){
            //System.out.println(" math <= eng");

        }else
        {
            //System.out.println("math > eng");
        }

在这两种地图中，老师是共同的，他们同时处理数学和英语科目并把它们反馈到每个下颈作为两个对象的值

我需要比较并找到最大反馈值，并仅将最大值打印到每个老师.... t 老师是这两个图中的共同键

Answer 1

您可以使用math entrySet（）迭代器键获取英文反馈图的值并选择最大值

        Map<String, Integer> maths = new HashMap<String, Integer>();
        maths.put("Nirmala", 70);
        maths.put("Subaksha", 80);
        Map<String, Integer> english = new HashMap<String, Integer>();
        english.put("Nirmala", 75);
        english.put("Subaksha", 60);

        System.out.println(english.entrySet());
        System.out.println(maths.entrySet());

        Map<String, Integer> top = new HashMap<String, Integer>();
        for (Map.Entry<String, Integer> math: maths.entrySet()){    
            System.out.println( "Teacher : " +math.getKey() + " Max Feedback :" + Math.max(math.getValue(), english.get(math.getKey())));
          }

Answer 2

这是我的建议；）

private void printMaxValues(Map<String, Integer> first, Map<String, Integer> second) {
    Set<String> keys = first.keySet();
    for (String s : keys) {
        Integer val1 = first.get(s);
        Integer val2 = second.get(s);
        if (val1 == null && val2 == null) {
            System.out.println("No values for key: " + s);
        } else if (val1 == null) {
            System.out.println(s + "=" + val2);
        } else if (val2 == null) {
            System.out.println(s + "=" + val1);
        } else {
            System.out.println(s + "=" + Math.max(val1, val2));
        }
    }
}

Answer 3

您可以执行以下操作：

1。。因为关键是老师，而价值就是它的全部回报

map

2。从反馈中获取一个Map<String, List<Integer>> feedbacks = Stream.of(maths, english) .flatMap(map -> map.entrySet().stream()) .collect(Collectors.toMap(e -> e.getKey(), e -> new ArrayList<Integer>(Arrays.asList(e.getValue())), (l1, l2)-> {l1.addAll(l2); return l1;})); System.out.println(feedbacks); //{Subaksha=[80, 60], Nirmala=[70, 75]}，因为关键是老师，而值是其反馈的最大值

map

Answer 4

您可以尝试以下操作：

static <V extends Comparable<V>>
boolean valuesEquals(Map<?,V> map1, Map<?,V> map2) {
    List<V> values1 = new ArrayList<V>(map1.values());
    List<V> values2 = new ArrayList<V>(map2.values());
    Collections.sort(values1);
    Collections.sort(values2);
    return values1.equals(values2);
}

或

map1.keySet().equals(map2.keySet())

比较值。如果equals为true，则可以找到两个值中的更大Key。

引用：http://thelogofthewook.blogspot.com/2011/12/hashmap-comparison-how-to-compare-two.html

Answer 5

您可以通过迭代两个现有地图，然后将分数放入其中，为您填写的每个教师钥匙（Map<String, Collection<Integer>>）创建一个助手集合。

或者您可以在两个地图的entrySets上创建Java 8 Stream，然后通过调用Collectors utils将它们合并为一个Map：

Map<String, Optional<Integer>> data = Arrays.asList( map1.entrySet(), map2.entrySet() )
            .stream()
            .flatMap( Set::stream )
            .collect( Collectors.groupingBy( Entry::getKey, HashMap::new, Collectors.mapping( Entry::getValue, Collectors.maxBy( Integer::compare ) ) ) );

    for( Entry<String, Optional<Integer>> entry : data.entrySet() )
    {
        System.out.println( entry.getKey() + ": " + entry.getValue().orElse( 0 ) );
    }

Answer 6

如果您确定将获得针对每个学科的每位老师的反馈，则可以使用以下内容。

Map<String, Integer> maths = new HashMap<String, Integer>();
maths.put("T1", 75);
maths.put("T2", 68);
maths.put("T3", 80);

Map<String, Integer> english = new HashMap<String, Integer>();
english.put("T1",60);
english.put("T2",70);
english.put("T3",79);

for(String s:maths.keySet())
    System.out.println("Teacher "+s+" with max feedback:"+Math.max(maths.get(s),english.get(s)));

如何通过两个地图的值比较两个地图并为每个键打印最大值（两个地图中的键都相同）

6 个答案: