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package
com.shellway.javase;
import
java.util.ArrayList;
import
java.util.Collection;
import
java.util.HashSet;
import
java.util.Iterator;
import
java.util.List;
import
java.util.Map;
import
java.util.Set;
import
java.util.TreeMap;
import
org.junit.Test;
public
class
TestCollection {
public
static
void
print(Collection
extends
Object> c){
Iterator
extends
Object> it = c.iterator();
while
(it.hasNext()) {
Object object = (Object) it.next();
System.out.println(object);
}
}
@Test
public
void
demo1(){
Set
new
HashSet
set.add(
"AAA"
);
set.add(
"BBB"
);
set.add(
"CCC"
);
print(set);
//Set的第一种遍历方式:利用Iterator
Iterator
for
(String ss : set) {
System.out.println(ss);
}
//Set的第一种遍历方式:利用foreach
for
(String sss : set) {
System.out.println(sss);
}
List
new
ArrayList
list.add(
"DDDDD"
);
list.add(
"EEEEE"
);
list.add(
"FFFFF"
);
print(list);
//List的第一种遍历方式:因为list有顺序,利用size()和get()方法获取
for
(
int
i =
0
; i < list.size(); i++) {
System.out.println(list.get(i));
}
//List的第二种遍历方式:利用Iterator
Iterator
while
(it.hasNext()) {
System.out.println(it.next());
}
//List的第三种遍历方式:利用foreach
for
(String s2 : list) {
System.out.println(s2);
}
Map
new
TreeMap
map.put(
"Jerry"
,
"10000"
);
map.put(
"shellway"
,
"20000"
);
map.put(
"Kizi"
,
"30000"
);
print(map.entrySet());
//Map的第一种遍历方式:先获得key,再获得值value
Set
for
(String s : sett) {
System.out.println(s+
":"
+map.get(s));
}
//Map的第二种遍历方式:获得键值对
for
(Map.Entry
System.out.println(entry.getKey()+
" : "
+entry.getValue());
}
}
}
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