Map的迭代方式

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class TestMap {
public static void main(String[] args) {
Map<Integer, String> map = new HashMap<>();
map.put(1, "a");
map.put(2, "b");
map.put(3, "c");
map.put(4, "d");
map.put(5, "e");

// 使用map.keySet();
Set<Integer> set = map.keySet();
// for-each循环迭代
for (Integer integer : set) {
System.out.print(map.get(integer) + "\t");
}
System.out.println();
// Iterator迭代器迭代
Iterator<Integer> it = set.iterator();
while (it.hasNext()) {
System.out.print(map.get(it.next()) + "\t");
}
// 使用map.entrySet();
System.out.println();
Set<Entry<Integer, String>> set2 = map.entrySet();
// Iterator迭代器迭代
Iterator<Entry<Integer, String>> it2 = set2.iterator();
while (it2.hasNext()) {
Entry<Integer, String> e = it2.next();
System.out.print(e.getKey() + "\t" + e.getValue() + "\n");
}
// for-each循环迭代
for (Entry<Integer, String> entry : set2) {
System.out.print(entry.getKey() + "\t" + entry.getValue() + "\n");
}
}
}