首先,打开你喜欢的集成开发环境(IDE),比如Eclipse、IntelliJ IDEA等。 Step 2: Create a new Java project 在IDE中创建一个新的Java项目,命名为任意想要的名字,比如"EmptyListProject"。 Step 3: Create a new Java class 在项目中创建一个新的Java类,命名为Main或者其他你喜欢的名字。 Step 4: Import the L...
importjava.util.ArrayList;importjava.util.HashMap;importjava.util.HashSet;importjava.util.List;importjava.util.Map;importjava.util.Set;// 创建工具类 CollectionUtilpublicclassCollectionUtil{// 创建List类型的空集合publicstaticList<String>createEmptyList(){returnnewArrayList<>();}// 创建Set类型的空集合...
* This example illustrates the type-safe way to obtain an empty list: * * List<String> s = Collections.emptyList(); * * Implementation note: Implementations of this method need not * create a separate List object for each call. Using this * method is likely to have comparable cost t...
* List<String> s = Collections.emptyList();* * Implementation note: Implementations of this method need not * create a separate List object for each call. Using this * method is likely to have comparable cost to using the like-named * field. (Unlike this method, the field doe...
创建空集合 Collections.emptyList(); 创建单元素集合 Collections.singletonList("apple"); 排序Collections.sort(list); 创建不可变集合 Collections.unmodifiableList(mutable); 创建线程安全集合 Collections.synchronizedList(list); ... Guava 沿着 Collections 的思路 提供了 更多的工具方法,适用于所有集合的静态方法,...
* List<String> s = Collections.emptyList(); * * Implementation note: Implementations of this method need not * create a separate List objectforeachcall. Using this * method is likely to have comparable cost to using the like-named * field. (Unlike this...
* List<String> s = Collections.emptyList(); * * Implementation note: Implementations of this method need not * create a separate List object for each call. Using this * method is likely to have comparable cost to using the like-named * field. (Unlike this...
void addToList(Object x) { getOrCreateList().add(x); } private list getOrCreateList() { // To conserve memory, we don't create the list until the first use if (list == null) list = new ArrayList(); return list; } 请记住,您有时需要采取额外的措施来解决可能的并发问题。例如,如果...
CREATE TABLE customer ( id VARCHAR(40) PRIMARY KEY, name VARCHAR(20) NOT NULL, gender VARCHAR(10) NOT NULL, birthday DATE, cellphone VARCHAR(30) NOT NULL, email VARCHAR(30), preference VARCHAR(200), type VARCHAR(20), description VARCHAR(255) ...
(Collectors.toList())转换成数组if(createTempTable(tableName,columns)){//创建临时表表List<Map<String,String>>temp=records;SQLsqlTemplate=newSQL();//sql模板sqlTemplate.INSERT_INTO(tableName);//表名sqlTemplate.INTO_COLUMNS(columns.toArray(newString[]{}));//列sqlTemplate.INTO_VALUES(columns....