Java 数组转成集合List三种方法和（数组、集合List、Set相互转换）

朱雀 2020-10-17 16:07 796阅读 0赞

### Java 数组转成集合List 三种方法 ###

package com.list;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;
    
    /**
     * Java 数组转成集合List
     * @author luolei
     * @date 2019年2月18日
     */
    public class ArrayToList {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		//1、new arr[]
    		//String[] arr = {"luo","lei","luolei"};
    		//2、new arr[]
    		/*String[] arr = new String[4];
    		arr[0] = "luo";
    		arr[1] = "lei";
    		arr[2] = "luolei";*/
    		//3 、new arr[]
    		String[] arr= new String[]{"luo","lei","luolei"};
    		
    		//1、拆分数组，逐个添加到List
    		List<String> list = new ArrayList<>(arr.length);
    		for (String str : arr) {
    			list.add(str);
    		}
    		System.out.println("list="+list); //list=[luo, lei, luolei]
    		
    		//2、addAll()
    		List<String> list2 = new ArrayList<>();
    		list2.addAll(list);
    		list2.addAll(list);
    		System.out.println("list2="+list2); //list2=[luo, lei, luolei, luo, lei, luolei]
    		
    		//3、Arrays.asList()
    		List<String> list3= new ArrayList<>(Arrays.asList(arr));
    		System.out.println("list3="+list3); //list3=[luo, lei, luolei]
    	}
    
    }

###  数组、集合List、Set相互转换 ###

package com.list;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.HashSet;
    import java.util.List;
    import java.util.Set;
    /**
     * 数组、List、Set相互转换
     * @author luolei
     * @date 2019年2月18日
     */
    public class ArrayAndListAndSetConvertion {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		
    		String[] arr= new String[]{"luo","lei","luolei"};
    		//数组转List
    		List<String> list= new ArrayList<>(Arrays.asList(arr));
    		System.out.println("list="+list); //list=[luo, lei, luolei]
    		//数组转Set
    		Set<String> set= new HashSet<>(Arrays.asList(arr));
    		System.out.println("set="+set); //set=[luolei, luo, lei]
    		//List转Set
    		Set<String> set2 = new HashSet<String>(list);
    		System.out.println("set2="+set2); //set2=[luolei, luo, lei]
    		//Set转List
    		List<String> list2 = new ArrayList<String>(set2);
    		System.out.println("list2="+list2); //list2=[luolei, luo, lei]
    	}
    
    }