we have this string: String input1 = "abbccd";

expected output: ab2c2d (note: if count=1, it shouldn't show in output).

the following code outputs a1,b2 c2 d2 on separate lines. Any suggestion to fix and improve?

input1.chars()
      .mapToObj(s -> Character.toLowerCase(Character.valueOf((char) s)))
      .collect(Collectors.groupingBy(Function.identity(), LinkedHashMap::new, Collectors.counting()))
      .entrySet().stream()
      .forEach(n -> {System.out.println(n.getKey() "" n.getValue());});

CodePudding user response：

Make the last forEach a map instead.

Instead of n.getValue() only add that part if n.getValue is not 1.

Then collect by joining.

At that point you will have a string you can print.

So, assuming we don't want to change your first part:

"abbccd".chars()
        .mapToObj(s -> Character.toLowerCase((char)s)) // notice here Character.valueOf was redundant, we're already dealing with a char
        .collect(Collectors.groupingBy(Function.identity(), LinkedHashMap::new, Collectors.counting()))
        .entrySet().stream()
        .map(n -> n.getKey() "" (n.getValue() == 1 ? "" : n.getValue()))
        .collect(Collectors.joining());

Results in ab2c2d.

CodePudding user response：

Unfortunately, the other two Answers both fail with most characters.

Avoid legacy type char

The char type is legacy, essentially broken since Java 2, legacy since Java 5. As a 16-bit value, char is physically incapable of representing most of the 144,697 characters defined in Unicode.

See one Answer’s code break:

String input = "