如何在 Java 中按值对树形图进行排序？
在 Java 语言中，树形图总是存储键-值对，这些键-值对在键的基础上按排序顺序排列。TreeMap 实现了导航地图接口，扩展了抽象地图类。TreeMap 包含唯一的键。
在 Java 中按值排序树形图
- 树形图中的元素是根据关键字排序的。
- 所以，我们需要发展自己的逻辑，在价值的基础上进行排序。我们可以使用比较器类来实现
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to Sort a TreeMap By Value
import java.util.*;
class GFG {
public static <K, V extends Comparable<V> > Map<K, V>
valueSort(final Map<K, V> map)
{
// Static Method with return type Map and
// extending comparator class which compares values
// associated with two keys
Comparator<K> valueComparator = new Comparator<K>() {
// return comparison results of values of
// two keys
public int compare(K k1, K k2)
{
int comp = map.get(k1).compareTo(
map.get(k2));
if (comp == 0)
return 1;
else
return comp;
}
};
// SortedMap created using the comparator
Map<K, V> sorted = new TreeMap<K, V>(valueComparator);
sorted.putAll(map);
return sorted;
}
public static void main(String[] args)
{
TreeMap<String, Integer> map = new TreeMap<String, Integer>();
// Put elements to the map
map.put("Anshu", 2);
map.put("Rajiv", 4);
map.put("Chhotu", 3);
map.put("Golu", 5);
map.put("Sita", 1);
// Calling the method valueSort
Map sortedMap = valueSort(map);
// Get a set of the entries on the sorted map
Set set = sortedMap.entrySet();
// Get an iterator
Iterator i = set.iterator();
// Display elements
while (i.hasNext()) {
Map.Entry mp = (Map.Entry)i.next();
System.out.print(mp.getKey() + ": ");
System.out.println(mp.getValue());
}
}
}
Output
Sita: 1
Anshu: 2
Chhotu: 3
Rajiv: 4
Golu: 5
例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to Sort a TreeMap By Value
import java.util.*;
class GFG {
// Method for sorting the TreeMap based on values
public static <K, V extends Comparable<V> > Map<K, V>
valueSort(final Map<K, V> map)
{
// Static Method with return type Map and
// extending comparator class which compares values
// associated with two keys
Comparator<K> valueComparator = new Comparator<K>()
{
public int compare(K k1, K k2)
{
int comp = map.get(k1).compareTo(map.get(k2));
if (comp == 0)
return 1;
else
return comp;
}
};
// SortedMap created using the comparator
Map<K, V> sorted = new TreeMap<K, V>(valueComparator);
sorted.putAll(map);
return sorted;
}
public static void main(String[] args)
{
TreeMap<Integer, String> map
= new TreeMap<Integer, String>();
// Put elements to the map
map.put(1, "Anshu");
map.put(5, "Rajiv");
map.put(3, "Chhotu");
map.put(2, "Golu");
map.put(4, "Sita");
// Calling the method valueSort
Map sortedMap = valueSort(map);
// Get a set of the entries on the sorted map
Set set = sortedMap.entrySet();
// Get an iterator
Iterator i = set.iterator();
while (i.hasNext())
{
Map.Entry mp = (Map.Entry)i.next();
System.out.print(mp.getKey() + ": ");
System.out.println(mp.getValue());
}
}
}
Output
1: Anshu
3: Chhotu
2: Golu
5: Rajiv
4: Sita
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