一、List(有序,可重复)
1.Foreach
public class TestCase {
public class St(){
public int id;
public String name;
St(int id, String name){this.id=id;this.name=name}
}//构造函数
public static void main(String[] args) {
St st=new St(1,"Jack");
St st1=new St(3,"Jack5");
St st2=new St(2,"Jack7");
ArrayList<St>list=new ArrayList();
list.add(st);list.add(st1);list.add(st2);
for (St s:list){
System.out.println(s);
}
}`
2.For循环
public class TestCase {
public class St(){
public int id;
public String name;
St(int id, String name){this.id=id;this.name=name}
}
public static void main(String[] args) {
St st=new St(1,"Jack");
St st1=new St(3,"Jack5");
St st2=new St(2,"Jack7");
ArrayList<St>list=new ArrayList();
list.add(st);list.add(st1);list.add(st2);
for (int i=1;i<=list.size();i++){
System.out.println(list.get(i));
}
}}
3.迭代器
public class TestCase {
public class St(){
public int id;
public String name;
St(int id, String name){this.id=id;this.name=name}`
` }
public static void main(String[] args) {
St st=new St(1,"Jack");
St st1=new St(3,"Jack5");
St st2=new St(2,"Jack7");
ArrayList<St>list=new ArrayList();
list.add(st);list.add(st1);list.add(st2);
for (ListIterator iterator=list.listIterator();iterator.hasNext();)
{
System.out.println(iterator.next());
}
for (ListIterator iterator1=list.listIterator();iterator1.hasPrevious();)
{
System.out.println(iterator1.Previous()); //Listiterator可以对集合进行双向遍历
}
}
}
二、Set(无序,不可重复)
1.迭代器
public class TestCase {
public class St(){
public int id;
public String name;
St(int id, String name){this.id=id;this.name=name}`
` }
public static void main(String[] args) {
St st=new St(1,"Jack");
St st1=new St(3,"Jack5");
St st2=new St(2,"Jack7");
Set<St>set=new Hashset()
set.add(st);set.add(st1);set.add(st2);
for (ListIterator iterator=list.listIterator();iterator.hasNext();)
{
System.out.println(iterator.next());
}
}
2.Foreach
public class TestCase {
public class St(){
public int id;
public String name;
St(int id, String name){this.id=id;this.name=name}//构造函数`
` }
public static void main(String[] args) {
St st=new St(1,"Jack");
St st1=new St(3,"Jack5");
St st2=new St(2,"Jack7");
Set<St>set=new Hashset()
set.add(st);set.add(st1);set.add(st2);
for(St s1:set){
Object o=(Object)s1;
System.out.println(o)
}
}}
三、Map(无序,重复覆盖)
迭代器
(1) 通过Set容器(keyset)
public class TestCase {
public static void main(String[] args) {
Map<String,String>map=new Hashmap();
map.put("1","a");
map.put("2","b");
map.put("3","c");
Set<String>set=map.keyset();
iterator it=set.iterator();
while(it.hasNext()){
String c=it.next();
System.out.println(c+map.get(c));
}
}
}}
(2) 通过Set容器(Entryset)
public class TestCase {
public static void main(String[] args) {
Map<String,String>map=new Hashmap();
map.put("1","a");
map.put("2","b");
map.put("3","c");
Set<Map.Entry<String,String>>set=map.Entryset();
iterator<Map.Entry<String,String> it=set.iterator();
while(it.hasNext())
{
Object c=it.next();
System.out.println(c);
}
}
}