RTpublic class MapTest2 {
public Map<String, Integer> putkey(String string, Integer integer) {
Map<String, Integer> tempMap = new HashMap<String, Integer>();
tempMap.put("a", 1);
tempMap.put("b", 2);
tempMap.put("c", 3);
return tempMap; } public static void main(String[] args) {
Map map = new HashMap();
MapTest2 mt = new MapTest2();
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Entry) it.next();
Object key = entry.getKey();
Object value = entry.getValue();
System.out.println(" key " + key + " value " + value);
}
}
}
public Map<String, Integer> putkey(String string, Integer integer) {
Map<String, Integer> tempMap = new HashMap<String, Integer>();
tempMap.put("a", 1);
tempMap.put("b", 2);
tempMap.put("c", 3);
return tempMap; } public static void main(String[] args) {
Map map = new HashMap();
MapTest2 mt = new MapTest2();
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Entry) it.next();
Object key = entry.getKey();
Object value = entry.getValue();
System.out.println(" key " + key + " value " + value);
}
}
}
是new HashMap();
还是 new MapTest2();
putkey方法 前加个static
public static Map<String, Integer> putkey(String string, Integer integer) {
Map<String, Integer> tempMap = new HashMap<String, Integer>();
tempMap.put("a", 1);
tempMap.put("b", 2);
tempMap.put("c", 3);
return tempMap; } public static void main(String[] args) {
Map map = putkey("",0);
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Entry) it.next();
Object key = entry.getKey();
Object value = entry.getValue();
System.out.println(" key " + key + " value " + value);
}
}
}
key c value 3
key b value 2
Map map = mt.putkey(null, null);
Iterator it = map.entrySet().iterator();
...
为啥也可以了?
谁帮忙解释下