List转换成String字符串三种方式

List转换成String字符串思路分析：
1.List转化成String[],再通过String[]数组遍历拼接成String字符串;
2.List转化成String存到StringBuffer中,再通过StringButter中的append()方法拼接成String字符串;
注意：StringBuffer字符串变量、StringBuilder字符串变量在方式二和方式三种可以把StringBuffer换成StringBuilder，但需要了解二者之间的区别，网址：https://blog.csdn.net/u013131716/article/details/99628104

package com.test01.listtostring;

import java.util.ArrayList;
import java.util.List;
import org.junit.Test;

public class ListToStringTest {

/*
 * List转换成String字符串
 * 方式一：
 * 	分析：List转化成String[],再通过String[]数组遍历拼接成String字符串
 * 
 * List内容：[laoyi, laoer, laosan]
 * 结果：laoyi,laoer,laosan
 * */
@SuppressWarnings({ "rawtypes", "unchecked", "unused" })
@Test
public void listToString01(){
	
	List list = new ArrayList<>();
	list.add("laoyi");
	list.add("laoer");
	list.add("laosan");
	
	System.out.println("List数组："+list);
	if(list == null && list.size() == 0){
		System.out.println("list中的内容为空！");
	}else{
		
		String[] strArrStrings = new String[list.size()];
		String resultString = "";
		
		for(int i=0;i<=list.size()-1;i++){
			strArrStrings[i] = (String) list.get(i);
		}

		for(int j=0;j<=strArrStrings.length-1;j++){
			if(j < strArrStrings.length-1){
				resultString += strArrStrings[j] + ",";
			}else{
				resultString += strArrStrings[j];	
			}
		}
		System.out.println("最后拼接的字符串：" + resultString);
	}
}


/*
 * List转换成String字符串
 * 方式二：
 * 	分析：List转化成String存到StringBuilder中,再通过StringBuilder中的append()方法拼接成String字符串
 * 
 * List内容：[laoyi, laoer, laosan]
 * 结果：laoyi,laoer,laosan
 * */
@SuppressWarnings({ "unused" })
@Test
public void listToString03(){
	List list = new ArrayList<>();
	list.add("laoyi");
	list.add("laoer");
	list.add("laosan");
	
	if(null ==list && list.size()<=0){
		System.out.println("list内容为空！");
	}else{
		
		StringBuilder sb = new StringBuilder();
		String resultString = "";
		
		for(int i=0;i list = new ArrayList<>();
	list.add("laoyi");
	list.add("laoer");
	list.add("laosan");
	
	if(null ==list && list.size()<=0){
		System.out.println("list内容为空！");
	}else{
		
		StringBuilder sb = new StringBuilder();
		String resultString = "";
		boolean flag = false;
		for(String str : list){
			if(flag){
				sb.append(",");
			}else{
				flag = true;
			}
			sb.append(str);
		}	
		resultString = sb.toString();
		System.out.println("最后拼接的字符串结果：" + resultString);
	}	
}

}