Java Utililty Methods Map Invert

List of utility methods to do Map Invert

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Description

The list of methods to do Map Invert are organized into topic(s).

Method

MapinvertMap(final Map map)
Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values. 
final Map<V, K> out = new HashMap<V, K>(map.size());
for (final Entry<K, V> entry : map.entrySet()) {
    out.put(entry.getValue(), entry.getKey());
return out;
MapinvertMap(final Map map)
invert Map 
final Map<V, K> inverted = new IdentityHashMap<>(map.size());
for (final Map.Entry<K, V> entry : map.entrySet()) {
    inverted.put(entry.getValue(), entry.getKey());
return Collections.unmodifiableMap(inverted);
MapinvertMap(Map map)
Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values. 
Map out = new HashMap(map.size());
for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
    Map.Entry entry = (Map.Entry) it.next();
    out.put(entry.getValue(), entry.getKey());
return out;
MapinvertMap(Map map)
Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values. 
Map out = new HashMap(map.size());
for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
    Map.Entry entry = (Map.Entry) it.next();
    out.put(entry.getValue(), entry.getKey());
return out;
MapinvertMap(Map map)
invert Map 
Map<V, K> inverted = new HashMap<V, K>();
for (Map.Entry<K, V> entry : map.entrySet()) {
    inverted.put(entry.getValue(), entry.getKey());
return inverted;
MapinvertMap(Map map)
Invert map. 
Map<V, K> inv = new HashMap<V, K>();
for (Entry<K, V> entry : map.entrySet())
    inv.put(entry.getValue(), entry.getKey());
return inv;
MapinvertMap(Map map)
Inverts the given map from key-value mappings to value-key mappings

Note: this may have unintended results if a certain value is included in the map more than once 

Map<V, K> inverted = new HashMap<V, K>();
for (Map.Entry<K, V> entry : map.entrySet()) {
    inverted.put(entry.getValue(), entry.getKey());
return inverted;
HashMapinvertStringMap(Map input)
Inverts Map of Strings (values become keys, keys become values). 
HashMap<String, String> output = new HashMap<String, String>(input.size());
Set<Map.Entry<String, String>> entries = input.entrySet();
for (Map.Entry<String, String> entry : entries) {
    output.put(entry.getValue(), entry.getKey());
return output;