代码： 

public static void main(String[] args) {
        List<String> mobileList=new ArrayList<>();
        mobileList.add("110");
        mobileList.add("120");
        mobileList.add("119");
        String mobileStr= StringUtils.strip(mobileList.toString(),"[]").replace(" ", "");
        System.out.println(mobileStr);
    }

结果：

依赖：

<!-- commons-lang3 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.7</version>
        </dependency>