I would like to convert the string containing abc to a list of characters and a hashset of characters. How can I do that in Java ?

List charList = new ArrayList("abc".toCharArray());

解决方案

You will have to either use a loop, or create a collection wrapper like Arrays.asList which works on primitive char arrays (or directly on strings).

List list = new ArrayList();

Set unique = new HashSet();

for(char c : "abc".toCharArray()) {

list.add(c);

unique.add(c);

}

Here is an Arrays.asList like wrapper for strings:

public List asList(final String string) {

return new AbstractList() {

public int size() { return string.length(); }

public Character get(int index) { return string.charAt(index); }

};

}

This one is an immutable list, though. If you want a mutable list, use this with a char[]:

public List asList(final char[] string) {

return new AbstractList() {

public int size() { return string.length; }

public Character get(int index) { return string[index]; }

public Character set(int index, Character newVal) {

char old = string[index];

string[index] = newVal;

return old;

}

};

}

Analogous to this you can implement this for the other primitive types.

Note that using this normally is not recommended, since for every access you

would do a boxing and unboxing operation.