Java 數組轉成集合List三種方法和（數組、集合List、Set相互轉換）

Java 數組轉成集合List 三種方法

package com.list;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Java 數組轉成集合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、拆分數組，逐個添加到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]
	}

}

 數組、集合List、Set相互轉換

package com.list;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
 * 數組、List、Set相互轉換
 * @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"};
		//數組轉List
		List<String> list= new ArrayList<>(Arrays.asList(arr));
		System.out.println("list="+list); //list=[luo, lei, luolei]
		//數組轉Set
		Set<String> set= new HashSet<>(Arrays.asList(arr));
		System.out.println("set="+set); //set=[luolei, luo, lei]
		//List轉Set
		Set<String> set2 = new HashSet<String>(list);
		System.out.println("set2="+set2); //set2=[luolei, luo, lei]
		//Set轉List
		List<String> list2 = new ArrayList<String>(set2);
		System.out.println("list2="+list2); //list2=[luolei, luo, lei]
	}

}