Array to a string java8

 

 

public static String arrayToString(int[] arr) { // 1,2,3...
        StringBuffer sb = new StringBuffer();
        for (int k : arr) {
            if (sb.length() < 1) {
                sb.append(String.format("%d", k));
            } else {
                sb.append(String.format(",%d", k));
            }
        }
        return sb.toString();
    }

//         int [] = {1,2,3,4} ARR; 
        String [] = {ARR "0", ". 1", "2", ". 3", ". 4", ". 5" };
 // 
        // use StringUtils join method, a string array to a org.apache.commons.lang3.StringUtils 
        string Str3 = StringUtils.join (ARR); // array to a string, in fact, is used to traverse 
        System.out.println (str3 ); // 012345 
        string str4 = StringUtils.join (ARR, ","); // array to a string (comma delimited) (recommended) 
        System.out.println (str4); // 0,1,2,3 , 4,5 

        // use ArrayUtils toString method, a string array to a org.apache.commons.lang3.ArrayUtils 
        string str2 = ArrayUtils.toString (ARR, ",");// array to a string (comma separated, inclusive increase parentheses)
        System.out.println(str2); // {0,1,2,3,4,5}

 

 

Without delimiters

　　

        int[] arr = {1,2,3,4};
//
        String str1 = Arrays.stream(arr).boxed().map(i -> i.toString()) //必须将普通数组 boxed才能 在 map 里面 toString
                .collect(Collectors.joining(""));
        System.out.println(str1);

        String str2 = Arrays.stream(arr).boxed().map(i -> i.toString()).reduce("", String::concat);
        System.out.println(str2);

        String str3 = Arrays.stream(arr).boxed().map(Object :: toString).reduce("", String::concat); // 方法引用Object：：toString
        System.out.println(str3);

 

list -> string delimited

List<String> list = Arrays.asList("北京","南京","重庆","西安");

        String str1 = String.join(",",list);
        System.out.println(str1);

        String str2 = list.stream().collect(Collectors.joining(","));
        System.out.println(str2);