java.lang.String 不能转换为 java.util.Map$Entry
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时间：2020-08-12 19:12:37 来源:igfitidea点击:
java.lang.String cannot be cast to java.util.Map$Entry
提问by
public static void main(String[] args) {
// TODO Auto-generated method stub
Map<String,String> map = new HashMap<String,String>();
Iterator itr = null;
StringBuffer sb = null;
Entry entry = null;
String key = null;
String val = null;
map.put("1", "Rakesh");
map.put("2", "Amal");
map.put("3", "Nithish");
itr = map.keySet().iterator();
sb = new StringBuffer();
while(itr != null && itr.hasNext()) {
try {
entry = (Entry) itr.next();
key = (String) entry.getKey();
val = (String) entry.getValue();
System.out.println(key);
System.out.println(val);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Map$Entry
at com.sixdee.prepaidwork.MapZ.main(MapZ.java:38)
java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Map$Entry
at com.sixdee.prepaidwork.MapZ.main(MapZ.java:38)
java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Map$Entry
at com.sixdee.prepaidwork.MapZ.main(MapZ.java:38)
回答by Louis Wasserman
itr = map.keySet().iterator();
should be
应该
itr = map.entrySet().iterator();
...as you would have noticed if you'd used generics properly throughout your program, by giving itrtype Iterator<Map.Entry<String, String>>and entrytype Map.Entry<String, String>.
...正如您所注意到的，如果您在整个程序中正确使用泛型，通过提供itrtypeIterator<Map.Entry<String, String>>和entrytype Map.Entry<String, String>。
