2017-07-10 22:24:57java
blog sitegit
https://github.com/Fiz1994github
package com.learn; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; /** * Created by fiz on 7/10/17. */ public class CollectionTest { public static void main(String[] a){ Collection<String> collection = new ArrayList<>(); // add element collection.add("item1"); collection.add("item2"); collection.add("item3"); collection.add("item4"); // remove collection.remove("item1"); //流輸出打印 collection.forEach(System.out::println); collection.stream().forEach(System.out::println); //for Iterator<String> iterator = collection.iterator(); while (iterator.hasNext()){ System.out.println(iterator.next()); } } }
package com.learn; import java.util.ArrayList; import java.util.List; import java.util.Iterator; import java.util.List; /** * Created by fiz on 7/10/17. */ public class ListTest { public static void main(String[] a) { List<String> list = new ArrayList<>(); // add element list.add("item1"); list.add("item2"); list.add("item3"); list.add("item4"); // remove list.remove("item1"); //流輸出打印 list.forEach(System.out::println); list.stream().forEach(System.out::println); //for Iterator<String> iterator = list.iterator(); while (iterator.hasNext()) { System.out.println(iterator.next()); } // 比collection 新增的方法 System.out.println(list.get(2)); System.out.println(list.set(2,"fiz")); System.out.println(list.get(2)); } }
Set<Integer> set = new HashSet<Integer>(); //添加元素 set.add(1); set.add(2); set.add(3); set.add(4); // 存儲相同的元素不會報錯,會自動去重 set.add(4); // 刪除元素 set.remove(1); set.forEach(System.out::println); // 查找元素 List<Integer> list = new ArrayList<Integer>(set); list.get(10); //經常使用屬性 set.isEmpty(); set.size(); Map; Map<Object,String> map = new HashMap<Object, String>(); // 添加元素 map.put(1,"demo"); map.put(2,"demo"); map.put(3,"demo"); map.put(4,"demo"); // 刪除元素 map.remove(2); map.remove(2,"demo"); //查找元素 map.containsKey("key"); map.containsValue("value"); System.out.println(map.get(1)); Set s = map.entrySet(); // 轉換爲set Iterator iterator = s.iterator(); while (iterator.hasNext()){ System.out.println(iterator.next()); } // 包含的屬性 map.size(); map.isEmpty(); map.put(1,"demo");