使用索引迭代 Java Map
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Iterate Java Map with index
提问by Sam Joos
How can I iterate a Map to write the content from certain index to another.
如何迭代 Map 以将内容从某个索引写入另一个。
Map<String, Integer> map = new LinkedHashMap<>();
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(file));
for (String string : map.keySet()) {
bufferedWriter.write(string + " " + map.get(string));
bufferedWriter.newLine();
}
bufferedWriter.close();
I have two int values, from and to, how can I now write for example from 10 to 100? is there any possibility to iterate the map with index?
我有两个 int 值，from 和 to，我现在怎么写，例如从 10 到 100？有没有可能用索引迭代地图？
回答by M Anouti
LinkedHashMappreserves the order in which entries are inserted. So you can try to create a list of the keys and loop using an index:
LinkedHashMap保留条目插入的顺序。因此，您可以尝试使用索引创建键列表和循环：
List<String> keyList = new ArrayList<String>(map.keySet());
for(int i = fromIndex; i < toIndex; i++) {
String key = keyList.get(i);
String value = map.get(key);
...
}
Another way without creating a list:
另一种不创建列表的方法：
int index = 0;
for (String key : map.keySet()) {
if (index++ < fromIndex || index++ > toIndex) {
continue;
}
...
}
回答by Sarthak Mittal
You can increase an int variable along with that loop:
您可以在该循环中增加一个 int 变量：
int i = - 1;
for (String string : map.keySet()) {
i++;
if (i < 10) {
// do something
} else {
// do something else
}
bufferedWriter.write(string + " " + map.get(string)); // otherwise...
bufferedWriter.newLine();
}
