List:[“a”,“b”,“c”]
转换后：a,b,c
1、String.join
// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);String join = String.join(",", list);//join = a,b,cSystem.out.println("join = " + join);
2、谷歌工具类 Joiner
import com.google.common.base.Joiner;
// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);String join = Joiner.on(",").join(list);//join = a,b,cSystem.out.println("join = " + join);3、forEach
// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);StringBuffer join = new StringBuffer();//和list.forEach没啥区别//list.stream().forEach(s -> join.append(s).append(","));//可以并行处理//list.parallelStream().forEach(s -> join.append(s).append(","));list.forEach(s -> join.append(s).append(","));//join = a,b,cSystem.out.println("join = " + join);
4、list.stream
// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);//map(String::toString)将流中的每个元素转换为字符串String join = list.stream().map(String::toString).collect(Collectors.joining(","));//map(String::valueOf)也将流中的每个元素转换为字符串，但对于非字符串类型的元素，会先调用toString()方法转换为字符串String join1 = list.stream().map(String::valueOf).collect(Collectors.joining(","));//join = a,b,cSystem.out.println("join = " + join);
5、apache 工具类
import org.apache.tomcat.util.buf.StringUtils;
// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);String join = StringUtils.join(list, ',');//join = a,b,cSystem.out.println("join = " + join);
import org.apache.commons.lang.StringUtils;
// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);//String join = StringUtils.join(list, ","); 单引号，双引号都可以String join = StringUtils.join(list, ',');//join = a,b,cSystem.out.println("join = " + join);
6、for 循环
StringBuffer join = new StringBuffer();// 1. 创建一个List集合 数量不可变List<String> list = List.of("a", "b", "c");//list = [a, b, c]System.out.println("list = " + list);for (int i = 0; i < list.size(); i++) {join.append(list.get(i));if (i != list.size() - 1) {join.append(",");}}//join = a,b,cSystem.out.println("join = " + join);
)
