显示集合接口使用的Java程序
Collection 框架是用于表示和操作集合的统一架构,使集合能够独立于实现细节进行操作。
集合框架的用途和优势:
- 这通过提供数据结构和算法减少了程序员的工作,因此我们不必编写它们。
- 这通过提供数据结构和算法的高性能实现来提高性能。
- 这通过建立一种公共语言来来回传递集合,从而在不相关的 API 之间提供互操作性。
- 通过要求您学习多个临时集合 API 来减少学习 API 所需的工作量。
- 这提供了对集合执行有用功能的静态方法,例如对列表进行排序。
- 这提供了 Wrapper 实现,它向其他实现添加了功能,例如同步。
它为我们提供了使用和解决发展问题的更多优势。
用法:下面给出了不同类型接口的示例:
- 列表界面
- 喜欢的列表
- 地图界面
- 堆栈
用例 1:列表接口
Java
// Java Program that Shows Use of Collection Interface
// ArrayList
import java.util.*;
class GFG {
public static void main(String args[])
{
ArrayList list = new ArrayList();
list.add("Geeks");
list.add("areyou");
list.add("working");
list.add("hard?");
Iterator itr = list.iterator();
while (itr.hasNext()) {
System.out.println(itr.next());
}
}
}
Java
// Java Program that Shows Use of Collection Interface
// LinkedList
import java.util.*;
// Class testing java Collection
public class GFG {
// Main driver method
public static void main(String args[])
{
// Creating a LinkedList
LinkedList al = new LinkedList();
// Adding elements to above linked list
al.add("Geeks");
al.add("areyou");
al.add("working");
al.add("hard?");
// Iterator
Iterator itr = al.iterator();
// Condition check over elements inside using
// hasNext() method which holds true till there is
// element inside list
while (itr.hasNext()) {
// Printing elements of LinkedList
System.out.println(itr.next());
}
}
}
Java
// Java Program that Shows Use of Collection Interface
// Hash-Map
import java.util.*;
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Creating a Map
Map map = new HashMap<>();
// Adding elements to map
map.put(1, "Geeks");
map.put(2, "are");
map.put(3, "you");
map.put(4, "working");
// Traversing Map
// Converting to Set so that traversal is accessed
Set set = map.entrySet();
// Iterator
Iterator itr = set.iterator();
// Condition check over elements inside using
// hasNext() method which holds true till there is
// element inside list
while (itr.hasNext()) {
// Converting to Map.Entry so that we can get
// key and value separately
Map.Entry entry = (Map.Entry)itr.next();
// Printing elements inside HashMap
System.out.println(entry.getKey() + " "
+ entry.getValue());
}
}
}
Java
// Java Program that Shows Use of Collection Interface
// Stack
import java.util.*;
public class GFG {
// Main driver method
public static void main(String args[])
{
// Creating a stack in memory
Stack stack = new Stack();
// Adding elements to stack
stack.push("Geeks");
stack.push("are");
stack.push("you");
stack.push("working");
stack.push("hard?");
// pop() returns all elements of stack
stack.pop();
//. iterator
Iterator itr = stack.iterator();
// Condition check over elements inside using
// hasNext() method which holds true till there is
// element inside list
while (itr.hasNext()) {
// Print all popped elements
System.out.println(itr.next());
}
}
}
输出
Geeks
areyou
working
hard?
用例 2:链表
Java
// Java Program that Shows Use of Collection Interface
// LinkedList
import java.util.*;
// Class testing java Collection
public class GFG {
// Main driver method
public static void main(String args[])
{
// Creating a LinkedList
LinkedList al = new LinkedList();
// Adding elements to above linked list
al.add("Geeks");
al.add("areyou");
al.add("working");
al.add("hard?");
// Iterator
Iterator itr = al.iterator();
// Condition check over elements inside using
// hasNext() method which holds true till there is
// element inside list
while (itr.hasNext()) {
// Printing elements of LinkedList
System.out.println(itr.next());
}
}
}
输出
Geeks
areyou
working
hard?
用例 3:地图界面
Java
// Java Program that Shows Use of Collection Interface
// Hash-Map
import java.util.*;
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Creating a Map
Map map = new HashMap<>();
// Adding elements to map
map.put(1, "Geeks");
map.put(2, "are");
map.put(3, "you");
map.put(4, "working");
// Traversing Map
// Converting to Set so that traversal is accessed
Set set = map.entrySet();
// Iterator
Iterator itr = set.iterator();
// Condition check over elements inside using
// hasNext() method which holds true till there is
// element inside list
while (itr.hasNext()) {
// Converting to Map.Entry so that we can get
// key and value separately
Map.Entry entry = (Map.Entry)itr.next();
// Printing elements inside HashMap
System.out.println(entry.getKey() + " "
+ entry.getValue());
}
}
}
输出
1 Geeks
2 are
3 you
4 working
用例 4:堆栈
Java
// Java Program that Shows Use of Collection Interface
// Stack
import java.util.*;
public class GFG {
// Main driver method
public static void main(String args[])
{
// Creating a stack in memory
Stack stack = new Stack();
// Adding elements to stack
stack.push("Geeks");
stack.push("are");
stack.push("you");
stack.push("working");
stack.push("hard?");
// pop() returns all elements of stack
stack.pop();
//. iterator
Iterator itr = stack.iterator();
// Condition check over elements inside using
// hasNext() method which holds true till there is
// element inside list
while (itr.hasNext()) {
// Print all popped elements
System.out.println(itr.next());
}
}
}
输出
Geeks
are
you
working