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[英]“Warning: [unchecked] unchecked cast” when casting Object to ArrayList<String[]>
[英]object to ArrayList<String> unchecked cast
使用-Xlint編譯我的代碼我發現了這個:
warning: [unchecked] unchecked cast
found : java.lang.Object
required: java.util.ArrayList<java.lang.String>
ArrayList<String> msgData = (ArrayList<String>)element;
這是代碼:
ArrayList<ArrayList<String>> msg = new ArrayList<ArrayList<String>>();
//add some data to msg
Iterator i = msg.iterator();
while(i.hasNext()) {
Object element = i.next();
ArrayList<String> msgData = (ArrayList<String>)element;
}
演員怎么辦?
你的迭代器也需要一個類型,如下所示:
ArrayList<ArrayList<String>> msg = new ArrayList<ArrayList<String>>();
//add some data to msg
Iterator<ArrayList<String>> i = msg.iterator();
while(i.hasNext()) {
ArrayList<String> element = i.next();
}
另外,最好是編程接口,而不是實現。 因此,你寫道:
List<List<String>> msg = new ArrayList<List<String>>();
//add some data to msg
Iterator<List<String>> i = msg.iterator();
while(i.hasNext()) {
List<String> element = i.next();
}
你的迭代器應該是這樣的
Iterator<ArrayList<String>> i = msg.iterator();
順便說一句,你可以使用for-each循環:
for (ArrayList<String> sublist : msg) {
....
}
ArrayList<ArrayList<String>> msg = new ArrayList<ArrayList<String>>();
//add some data to msg
for (ArrayList<String> msgData : msg) {
//do something
}
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