Nga Huarahi rereke ki te Whakauru Ma te Mahere i Java

Kei te tarai i te Mahere i Java. I tenei panui, ka tirohia e wha nga momo huarahi e taea ai te whakamarama ma te mapi i Java. I te Java 8, ka taea e taatau te whakamahi i te tikanga forEach me te karaehe tautuhi hei koropiko i runga i te mapi.

Me Pehea te Whakauru i nga Whakauru Mahere (Kī me nga Uara)

Map map = new HashMap(); for (Map.Entry entry : map.entrySet()) {
System.out.println('Key = ' + entry.getKey() + ', Value = ' + entry.getValue()); }

Me Pehea te Whakauru i Nga Kī Mahere anake

Map map = new HashMap(); for (Integer key : map.keySet()) {
System.out.println('Key = ' + key); }

Me Pehea Te Whakauru I Nga Uara Mahere anake

for (Integer value : map.values()) {
System.out.println('Value = ' + value); }

E pā ana:

• Me pehea te huri i nga Raarangi Array i Java

Te whakamahi i a Iterator

Ma te whakamahi i nga Generics:

Map map = new HashMap(); Iterator entries = map.entrySet().iterator(); while (entries.hasNext()) {
Map.Entry entry = entries.next();
System.out.println('Key = ' + entry.getKey() + ', Value = ' + entry.getValue()); }

Kaore he Generics:

Map map = new HashMap(); Iterator entries = map.entrySet().iterator(); while (entries.hasNext()) {
Map.Entry entry = (Map.Entry) entries.next();
Integer key = (Integer)entry.getKey();
Integer value = (Integer)entry.getValue();
System.out.println('Key = ' + key + ', Value = ' + value); }

Te taatai ​​i nga taviri me te rapu uara

Map map = new HashMap(); for (Integer key : map.keySet()) {
Integer value = map.get(key);
System.out.println('Key = ' + key + ', Value = ' + value); }

Te whakamahi i te Java 8 Mo Ia Tahi

Map items = new HashMap();
items.put('key 1', 1);
items.put('key 2', 2);
items.put('key 3', 3);
items.forEach((k,v)->System.out.println('Item : ' + k + ' Count : ' + v));