I have an Map Map1 and another Map Map2..
Map<Key,ProductEntity> Map1;
Map<Key, ProductEntitySecond> Map2;
I want to iterate in map1 and check if that particular key of Map1 is present in Map2. if it is then return the value .
Can someone please give me an idea to solve that type of problem.
Maybe you can do something like this:
map1
.entrySet()
.stream()
.filter(e -> map2.containsKey(e.getKey()))
.findFirst()
.map(e -> e.getValue())
.orElse(null);
So if the key is present in map2 it'll return the value from map1 otherwise, it'll return null
You can use the Stream API.
public class Application {
public static void main(String[] args) {
var map1 = new HashMap<Square, String>();
map1.put(new Square(2), "two");
map1.put(new Square(3), "three");
map1.put(new Square(4), "four");
map1.put(new Square(5), "five");
var map2 = new HashMap<Square, String>();
map2.put(new Square(2), "two");
map2.put(new Square(3), "three");
var valuesAlsoInMap2 = map1.entrySet().stream()
.filter(it -> map2.containsKey(it.getKey()))
.map(Map.Entry::getValue)
.toList();
System.out.println(valuesAlsoInMap2);
}
}
Expected result:
[two, three]
This is using a simple POJO Square to show you it does work with non-primitive types. To see which methods HashMap relies on have a look at this thread.
import java.util.Objects;
class Square extends shape{
private int side;
public Square(int side) {
this.side = side;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Square square = (Square) o;
return side == square.side;
}
#Override
public int hashCode() {
return Objects.hash(side);
}
#Override
public double Area() {
return side*side;
}
public int getSide() {
return side;
}
public void setSide(int side) {
this.side = side;
}
}
Here's another approach using an intersection operation (retainAll()) on the two maps' key sets.
Map<Key, ProductEntity> map1 = ...;
Map<Key, ProductEntitySecond> map2 = ...;
Map<Key, ProductionEntity> tmp = new HashMap<>(map1);
tmp.keySet().retainAll(map2.keySet());
Collection<ProductionEntity> shared = tmp.values();
This is simple and clean, but it's not the most efficient solution, if that matters in this case.
I will leave you with a very, very simplified example.
If you choose to go with a solution similar to this one I would strongly recommend you to read about how to overwrite Equals and Hashcode: https://www.baeldung.com/java-equals-hashcode-contracts
import java.util.Map;
import java.util.HashMap;
public class HelloWorld{
public static void main(String []args) {
Entity entity1 = new Entity();
entity1.id = 1L;
Entity entity2 = new Entity();
entity2.id = 1L;
Map map1 = new HashMap<Entity, String>();
map1.put(entity1, "one");
Map map2 = new HashMap<Entity, String>();
map2.put(entity2, "two");
System.out.println(map1.get(entity1));
System.out.println(map2.get(entity1));
}
private static class Entity {
public Long id;
#Override
public boolean equals(Object o) {
return ((Entity) o).id.equals(this.id);
}
}
}
As you can see even two different references but with same id are now considered equals.
for Any java version 8+
List<String> valuesFromMap2WhenKeysAreCommon =
map1.keySet().stream().filter(map1::containsKey).map(map2::get).collect(Collectors.toList());
I have a TreeMap<Integer, TreeMap<int[][], Integer>> jungle. When I try to execute the statements
TreeMap<int[][], Integer> tempMap = new TreeMap();
int[][] matrix = {{1}};
tempMap.put(matrix, 4);
this last line gives me the
java.lang.ClassCastException: [[I cannot be cast to java.base/java.lang.Comparable at java.base/java.util.TreeMap.compare
exception. Am I not allowed to use an int[][] as a key in a treeMap?
The purpose of a TreeMap is to have an ordered collection
A Red-Black tree based NavigableMap implementation. The map is sorted according to the natural ordering of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.
You must pass a Comparator that deals with int[][]; here an example with one that sorted based on the full sum of the array
class Custom2DArrayComparator implements Comparator<int[][]> {
private static int sum(int[][] v) {
return Arrays.stream(v).map(arr -> Arrays.stream(arr).sum())
.mapToInt(Integer::intValue).sum();
}
#Override
public int compare(int[][] o1, int[][] o2) {
return Integer.compare(sum(o1), sum(o2));
}
}
Use
public static void main(String[] args) {
TreeMap<int[][], Integer> tempMap = new TreeMap<>(new Custom2DArrayComparator());
int[][] matrix = {{1}};
tempMap.put(matrix, 4);
}
You can use the anonymous class to avoid creating a one outside
public static void main(String[] args) {
TreeMap<int[][], Integer> tempMap = new TreeMap<>(new Comparator<>() {
#Override
public int compare(int[][] o1, int[][] o2) {
return Integer.compare(sum(o1), sum(o2));
}
int sum(int[][] v) {
return Arrays.stream(v).map(arr -> Arrays.stream(arr).sum())
.mapToInt(Integer::intValue).sum();
}
});
int[][] matrix = {{1}};
tempMap.put(matrix, 4);
}
You'll need to implement your own logic in order for your key to be Comparable, as Johannes' comment points out. You could create a class that implements Comparator and pass it as argument at the initialization of the TreeMap.
Note that the default/overriden compare method would also be valid, as arrays are just Objects.
You could even implement all the logics for non-comparable Object keys you wish to insert in different Maps in a single class:
public class NonCompObjectKeyComparator implements Comparator<Object>
{
#Override
public int compare(Object o1, Object o2)
{
if (o1 instanceof int[][])
{
//((int[][])o1),((int[][])o2)//
}
else if (o1 instanceof String[])
{
//((String[])o1),((String[])o2)//
}
else if (o1 instanceof <OtherNonComparableObjType>)
{
//...
}
//...
return 0;
}
}
And then you got your überComparator there:
Comparator<Object> maCompa = new NonCompObjectKeyComparator();
TreeMap<int[][], Integer> tempMap = new TreeMap(maCompa);
TreeMap<String[], String> sArrayMap = new TreeMap(maCompa);
int[][] matrix = {{1}};
tempMap.put(matrix, 4);
String[] sKey = {"a"};
sArrayMap.put(sKey, "anotherWierdMap");
In order to create an specific int[][] comparator, just:
public class CustomKeyComparator implements Comparator<int[][]> {
public int compare(int[][] a1, int[][] a2) {
//your logic here
return 0;
}
}
and
TreeMap<int[][], Integer> tempMap = new TreeMap(new CustomKeyComparator());
int[][] matrix = {{1}};
tempMap.put(matrix, 4);
I have a HashMap with the following structure,
{val1#val2=val3#val4-val5}
where key = val1#val2 and value=val3#val4-val5 ,
HashMap<String, String> h = new HashMap<String, String>();
h.put("aaa#bbb", "111#444-555");
h.put("bbb#aaa", "222#ddd-222");
h.put("111#999", "000#213-aaa");
I have three conditions where I have to sort the map as,
1. By val1.
2. By val2.
3. By val3.
HashMaps don't guarantee order, in order to get sorted map you need to use LinkedHashMap.
To sort the keys you could use the java stream api, sort the map entries and the insert them in LinkedHashMap.
Map<String, String> h = new HashMap<>();
h.put("aaa#bbb", "111#444-555");
h.put("bbb#aaa", "222#ddd-222");
h.put("111#999", "000#213-aaa");
LinkedHashMap<String, String> linkedHashMap = new LinkedHashMap<>();
h.entrySet().stream()
.sorted(Comparator.comparing(e -> e.getKey().split("#")[0]))// sort by val1
.sorted(Comparator.comparing(e -> e.getKey().split("#")[1]))// sort by val2
.sorted(Comparator.comparing(e -> e.getValue().split("#")[0]))// sort by val3
.forEach(e -> {
linkedHashMap.put(e.getKey(), e.getValue());
});
This should work:
public static void main(String[] args) {
LinkedHashMap<String, String> map = new LinkedHashMap<>();
map.put("aa#bb", "11111#44-5555555");
map.put("bb#aa", "22222#ddd-222");
map.put("11#99", "00000#213-aaa");
Function<Map.Entry<String, String>, String> byVal1 =
entry -> entry.getKey().substring(0, entry.getKey().indexOf('#'));
Function<Map.Entry<String, String>, String> byVal2 =
entry -> entry.getKey().substring(entry.getKey().indexOf('#') + 1);
Function<Map.Entry<String, String>, String> byVal3 =
entry -> entry.getValue().substring(0, entry.getValue().indexOf('#'));
// Just change this value to sort by a different value
Function<Map.Entry<String, String>, String> value = byVal3;
List<Map.Entry<String, String>> asList = map.entrySet().stream().sorted(Comparator.comparing(value)).collect(Collectors.toList());
map.clear();
asList.forEach(entry -> map.put(entry.getKey(), entry.getValue()));
map.entrySet().stream().forEach(entry -> System.out.println(entry));
}
You of course don't have to create the byValX functions in the method and could use method references instead.
No idea if that is what you want to accomplish (clarify what needs to be done and I can adapt the solution), but you can use a TreeMap:
import java.util.Map;
import java.util.Objects;
import java.util.TreeMap;
public class TestDictionary {
public static void main(String[] args) {
Map<Key, Object> map = new TreeMap<>(new Comparator<Key>() {
#Override
public int compare(Key o1, Key o2) {
// do whatever you want here
return 0;
}
});
map.put(new Key("a", "b", "c"), new Value());
map.put(new Key("b", "c", "a"), new Value());
map.put(new Key("c", "b", "a"), new Value());
System.out.println(map);
}
static class Key {
String val1;
String val2;
String val3;
public Key(String val1, String val2, String val3) {
this.val1 = val1;
this.val2 = val2;
this.val3 = val3;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Key key = (Key) o;
return val1.equals(key.val1) &&
val2.equals(key.val2) &&
val3.equals(key.val3);
}
#Override
public int hashCode() {
return Objects.hash(val1, val2, val3);
}
}
static class Value {
int number;
}
}
How can I sort a LinkedHashMap based on its values given that the LinkedHashMap contains of String and Integer. So I need to sort it based on the Values which are Integers.
Thanks a lot
List<Map.Entry<String, Integer>> entries =
new ArrayList<Map.Entry<String, Integer>>(map.entrySet());
Collections.sort(entries, new Comparator<Map.Entry<String, Integer>>() {
public int compare(Map.Entry<String, Integer> a, Map.Entry<String, Integer> b){
return a.getValue().compareTo(b.getValue());
}
});
Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
for (Map.Entry<String, Integer> entry : entries) {
sortedMap.put(entry.getKey(), entry.getValue());
}
This is now quite a bit easier with Java 8 streams: you don't need the intermediate map to sort:
map.entrySet().stream()
.sorted(Map.Entry.comparingByValue())
.forEach(entry -> ... );
LinkedHashMap just maintains insertion order. If you want to sort based on value, you may need to write your own comparator.
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NavigableMap;
import java.util.SortedMap;
import java.util.TreeMap;
public class HashMapTest {
public static void main(String[] args) {
Map<String, Integer> map=new LinkedHashMap<String, Integer>();
map.put("a", 11);
map.put("B", 12);
map.put("c", 3);
map.put("d", 4);
map.put("e", 5);
map.put("f", 6);
map.put("g", 7);
map.put("h", 8);
map.put("i", 9);
map.put("j", 3);
map.put("k", 2);
map.put("l", 1);
List<Map.Entry<String, Integer>> entries = new
ArrayList<Map.Entry<String, Integer>>(map.entrySet());
Collections.sort(entries,new CustomizedHashMap());
Map<String, Integer> sortedMap = new LinkedHashMap<String,
Integer>();
for (Map.Entry<String, Integer> entry : entries) {
sortedMap.put(entry.getKey(), entry.getValue());
System.out.print( sortedMap.put(entry.getKey(),
entry.getValue())+" ");
}
}
}
class CustomizedHashMap implements Comparator<Map.Entry<String, Integer>> {
#Override
public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
// TODO Auto-generated method stub
return -o1.getValue().compareTo(o2.getValue());
}
}
This question already has answers here:
Sort a Map<Key, Value> by values
(64 answers)
Closed 6 years ago.
I need to sort my HashMap according to the values stored in it. The HashMap contains the contacts name stored in phone.
Also I need that the keys get automatically sorted as soon as I sort the values, or you can say the keys and values are bound together thus any changes in values should get reflected in keys.
HashMap<Integer,String> map = new HashMap<Integer,String>();
map.put(1,"froyo");
map.put(2,"abby");
map.put(3,"denver");
map.put(4,"frost");
map.put(5,"daisy");
Required output:
2,abby;
5,daisy;
3,denver;
4,frost;
1,froyo;
A generic version of a method to sort a Map resembles:
private static <K extends Comparable<K>, V extends Comparable<V>> Map<K, V> sort(
final Map<K, V> unsorted,
final boolean order) {
final var list = new LinkedList<>(unsorted.entrySet());
list.sort((o1, o2) -> order
? o1.getValue().compareTo(o2.getValue()) == 0
? o1.getKey().compareTo(o2.getKey())
: o1.getValue().compareTo(o2.getValue())
: o2.getValue().compareTo(o1.getValue()) == 0
? o2.getKey().compareTo(o1.getKey())
: o2.getValue().compareTo(o1.getValue()));
return list.stream().collect(
Collectors.toMap(
Entry::getKey, Entry::getValue, (a, b) -> b, LinkedHashMap::new
)
);
}
The following code offers ascending and descending sorting by value:
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
public class SortMapByValue
{
public static final boolean ASC = true;
public static final boolean DESC = false;
public static void main(String[] args)
{
// Creating dummy unsorted map
Map<String, Integer> unsortMap = new HashMap<String, Integer>();
unsortMap.put("B", 55);
unsortMap.put("A", 80);
unsortMap.put("D", 20);
unsortMap.put("C", 70);
System.out.println("Before sorting......");
printMap(unsortMap);
System.out.println("After sorting ascending order......");
Map<String, Integer> sortedMapAsc = sortByComparator(unsortMap, ASC);
printMap(sortedMapAsc);
System.out.println("After sorting descindeng order......");
Map<String, Integer> sortedMapDesc = sortByComparator(unsortMap, DESC);
printMap(sortedMapDesc);
}
private static Map<String, Integer> sortByComparator(Map<String, Integer> unsortMap, final boolean order)
{
List<Entry<String, Integer>> list = new LinkedList<Entry<String, Integer>>(unsortMap.entrySet());
// Sorting the list based on values
Collections.sort(list, new Comparator<Entry<String, Integer>>()
{
public int compare(Entry<String, Integer> o1,
Entry<String, Integer> o2)
{
if (order)
{
return o1.getValue().compareTo(o2.getValue());
}
else
{
return o2.getValue().compareTo(o1.getValue());
}
}
});
// Maintaining insertion order with the help of LinkedList
Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
for (Entry<String, Integer> entry : list)
{
sortedMap.put(entry.getKey(), entry.getValue());
}
return sortedMap;
}
public static void printMap(Map<String, Integer> map)
{
for (Entry<String, Integer> entry : map.entrySet())
{
System.out.println("Key : " + entry.getKey() + " Value : "+ entry.getValue());
}
}
}
Using newer Java features:
import java.util.*;
import java.util.Map.Entry;
import java.util.stream.Collectors;
public class SortMapByValue
{
private static final boolean ASC = true;
private static final boolean DESC = false;
public static void main(String[] args)
{
// Creating dummy unsorted map
Map<String, Integer> unsortMap = new HashMap<>();
unsortMap.put("B", 55);
unsortMap.put("A", 20);
unsortMap.put("D", 20);
unsortMap.put("C", 70);
System.out.println("Before sorting......");
printMap(unsortMap);
System.out.println("After sorting ascending order......");
Map<String, Integer> sortedMapAsc = sortByValue(unsortMap, ASC);
printMap(sortedMapAsc);
System.out.println("After sorting descending order......");
Map<String, Integer> sortedMapDesc = sortByValue(unsortMap, DESC);
printMap(sortedMapDesc);
}
private static Map<String, Integer> sortByValue(Map<String, Integer> unsortMap, final boolean order)
{
List<Entry<String, Integer>> list = new LinkedList<>(unsortMap.entrySet());
// Sorting the list based on values
list.sort((o1, o2) -> order ? o1.getValue().compareTo(o2.getValue()) == 0
? o1.getKey().compareTo(o2.getKey())
: o1.getValue().compareTo(o2.getValue()) : o2.getValue().compareTo(o1.getValue()) == 0
? o2.getKey().compareTo(o1.getKey())
: o2.getValue().compareTo(o1.getValue()));
return list.stream().collect(Collectors.toMap(Entry::getKey, Entry::getValue, (a, b) -> b, LinkedHashMap::new));
}
private static void printMap(Map<String, Integer> map)
{
map.forEach((key, value) -> System.out.println("Key : " + key + " Value : " + value));
}
}
In Java 8:
Map<Integer, String> sortedMap =
unsortedMap.entrySet().stream()
.sorted(Entry.comparingByValue())
.collect(Collectors.toMap(Entry::getKey, Entry::getValue,
(e1, e2) -> e1, LinkedHashMap::new));
Assuming Java, you could sort hashmap just like this:
public LinkedHashMap<Integer, String> sortHashMapByValues(
HashMap<Integer, String> passedMap) {
List<Integer> mapKeys = new ArrayList<>(passedMap.keySet());
List<String> mapValues = new ArrayList<>(passedMap.values());
Collections.sort(mapValues);
Collections.sort(mapKeys);
LinkedHashMap<Integer, String> sortedMap =
new LinkedHashMap<>();
Iterator<String> valueIt = mapValues.iterator();
while (valueIt.hasNext()) {
String val = valueIt.next();
Iterator<Integer> keyIt = mapKeys.iterator();
while (keyIt.hasNext()) {
Integer key = keyIt.next();
String comp1 = passedMap.get(key);
String comp2 = val;
if (comp1.equals(comp2)) {
keyIt.remove();
sortedMap.put(key, val);
break;
}
}
}
return sortedMap;
}
Just a kick-off example. This way is more useful as it sorts the HashMap and keeps the duplicate values as well.
map.entrySet().stream()
.sorted((k1, k2) -> -k1.getValue().compareTo(k2.getValue()))
.forEach(k -> System.out.println(k.getKey() + ": " + k.getValue()));
You don't, basically. A HashMap is fundamentally unordered. Any patterns you might see in the ordering should not be relied on.
There are sorted maps such as TreeMap, but they traditionally sort by key rather than value. It's relatively unusual to sort by value - especially as multiple keys can have the same value.
Can you give more context for what you're trying to do? If you're really only storing numbers (as strings) for the keys, perhaps a SortedSet such as TreeSet would work for you?
Alternatively, you could store two separate collections encapsulated in a single class to update both at the same time?
package com.naveen.hashmap;
import java.util.*;
import java.util.Map.Entry;
public class SortBasedonValues {
/**
* #param args
*/
public static void main(String[] args) {
HashMap<String, Integer> hm = new HashMap<String, Integer>();
hm.put("Naveen", 2);
hm.put("Santosh", 3);
hm.put("Ravi", 4);
hm.put("Pramod", 1);
Set<Entry<String, Integer>> set = hm.entrySet();
List<Entry<String, Integer>> list = new ArrayList<Entry<String, Integer>>(
set);
Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
public int compare(Map.Entry<String, Integer> o1,
Map.Entry<String, Integer> o2) {
return o2.getValue().compareTo(o1.getValue());
}
});
for (Entry<String, Integer> entry : list) {
System.out.println(entry.getValue());
}
}
}
As a kind of simple solution you can use temp TreeMap if you need just a final result:
TreeMap<String, Integer> sortedMap = new TreeMap<String, Integer>();
for (Map.Entry entry : map.entrySet()) {
sortedMap.put((String) entry.getValue(), (Integer)entry.getKey());
}
This will get you strings sorted as keys of sortedMap.
I extends a TreeMap and override entrySet() and values() methods. Key and value need to be Comparable.
Follow the code:
public class ValueSortedMap<K extends Comparable, V extends Comparable> extends TreeMap<K, V> {
#Override
public Set<Entry<K, V>> entrySet() {
Set<Entry<K, V>> originalEntries = super.entrySet();
Set<Entry<K, V>> sortedEntry = new TreeSet<Entry<K, V>>(new Comparator<Entry<K, V>>() {
#Override
public int compare(Entry<K, V> entryA, Entry<K, V> entryB) {
int compareTo = entryA.getValue().compareTo(entryB.getValue());
if(compareTo == 0) {
compareTo = entryA.getKey().compareTo(entryB.getKey());
}
return compareTo;
}
});
sortedEntry.addAll(originalEntries);
return sortedEntry;
}
#Override
public Collection<V> values() {
Set<V> sortedValues = new TreeSet<>(new Comparator<V>(){
#Override
public int compare(V vA, V vB) {
return vA.compareTo(vB);
}
});
sortedValues.addAll(super.values());
return sortedValues;
}
}
Unit Tests:
public class ValueSortedMapTest {
#Test
public void basicTest() {
Map<String, Integer> sortedMap = new ValueSortedMap<>();
sortedMap.put("A",3);
sortedMap.put("B",1);
sortedMap.put("C",2);
Assert.assertEquals("{B=1, C=2, A=3}", sortedMap.toString());
}
#Test
public void repeatedValues() {
Map<String, Double> sortedMap = new ValueSortedMap<>();
sortedMap.put("D",67.3);
sortedMap.put("A",99.5);
sortedMap.put("B",67.4);
sortedMap.put("C",67.4);
Assert.assertEquals("{D=67.3, B=67.4, C=67.4, A=99.5}", sortedMap.toString());
}
}
found a solution but not sure the performance if the map has large size, useful for normal case.
/**
* sort HashMap<String, CustomData> by value
* CustomData needs to provide compareTo() for comparing CustomData
* #param map
*/
public void sortHashMapByValue(final HashMap<String, CustomData> map) {
ArrayList<String> keys = new ArrayList<String>();
keys.addAll(map.keySet());
Collections.sort(keys, new Comparator<String>() {
#Override
public int compare(String lhs, String rhs) {
CustomData val1 = map.get(lhs);
CustomData val2 = map.get(rhs);
if (val1 == null) {
return (val2 != null) ? 1 : 0;
} else if (val1 != null) && (val2 != null)) {
return = val1.compareTo(val2);
}
else {
return 0;
}
}
});
for (String key : keys) {
CustomData c = map.get(key);
if (c != null) {
Log.e("key:"+key+", CustomData:"+c.toString());
}
}
}
package SortedSet;
import java.util.*;
public class HashMapValueSort {
public static void main(String[] args){
final Map<Integer, String> map = new HashMap<Integer,String>();
map.put(4,"Mango");
map.put(3,"Apple");
map.put(5,"Orange");
map.put(8,"Fruits");
map.put(23,"Vegetables");
map.put(1,"Zebra");
map.put(5,"Yellow");
System.out.println(map);
final HashMapValueSort sort = new HashMapValueSort();
final Set<Map.Entry<Integer, String>> entry = map.entrySet();
final Comparator<Map.Entry<Integer, String>> comparator = new Comparator<Map.Entry<Integer, String>>() {
#Override
public int compare(Map.Entry<Integer, String> o1, Map.Entry<Integer, String> o2) {
String value1 = o1.getValue();
String value2 = o2.getValue();
return value1.compareTo(value2);
}
};
final SortedSet<Map.Entry<Integer, String>> sortedSet = new TreeSet(comparator);
sortedSet.addAll(entry);
final Map<Integer,String> sortedMap = new LinkedHashMap<Integer, String>();
for(Map.Entry<Integer, String> entry1 : sortedSet ){
sortedMap.put(entry1.getKey(),entry1.getValue());
}
System.out.println(sortedMap);
}
}
public static TreeMap<String, String> sortMap(HashMap<String, String> passedMap, String byParam) {
if(byParam.trim().toLowerCase().equalsIgnoreCase("byValue")) {
// Altering the (key, value) -> (value, key)
HashMap<String, String> newMap = new HashMap<String, String>();
for (Map.Entry<String, String> entry : passedMap.entrySet()) {
newMap.put(entry.getValue(), entry.getKey());
}
return new TreeMap<String, String>(newMap);
}
return new TreeMap<String, String>(passedMap);
}
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map.Entry;
public class CollectionsSort {
/**
* #param args
*/`enter code here`
public static void main(String[] args) {
// TODO Auto-generated method stub
CollectionsSort colleciotns = new CollectionsSort();
List<combine> list = new ArrayList<combine>();
HashMap<String, Integer> h = new HashMap<String, Integer>();
h.put("nayanana", 10);
h.put("lohith", 5);
for (Entry<String, Integer> value : h.entrySet()) {
combine a = colleciotns.new combine(value.getValue(),
value.getKey());
list.add(a);
}
Collections.sort(list);
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
public class combine implements Comparable<combine> {
public int value;
public String key;
public combine(int value, String key) {
this.value = value;
this.key = key;
}
#Override
public int compareTo(combine arg0) {
// TODO Auto-generated method stub
return this.value > arg0.value ? 1 : this.value < arg0.value ? -1
: 0;
}
public String toString() {
return this.value + " " + this.key;
}
}
}