immutability

问题 This question already has an answer here: Immutability of Strings in Java 26 answers I wrote the following code on immutable Strings. public class ImmutableStrings { public static void main(String[] args) { testmethod(); } private static void testmethod() { String a = \"a\"; System.out.println(\"a 1-->\" + a); a = \"ty\"; System.out.println(\"a 2-->\" + a); } } Output: a 1-->a a 2-->ty Here the value of variable a has been changed (while many say that contents of the immutable objects cannot

问题 I\'m trying to remove specific characters from a string using Python. This is the code I\'m using right now. Unfortunately it appears to do nothing to the string. for char in line: if char in \" ?.!/;:\": line.replace(char,\'\') How do I do this properly? 回答1: Strings in Python are immutable (can't be changed). Because of this, the effect of line.replace(...) is just to create a new string, rather than changing the old one. You need to rebind (assign) it to line in order to have that variable

问题 I\'m confused on what an immutable type is. I know the float object is considered to be immutable, with this type of example from my book: class RoundFloat(float): def __new__(cls, val): return float.__new__(cls, round(val, 2)) Is this considered to be immutable because of the class structure / hierarchy?, meaning float is at the top of the class and is its own method call. Similar to this type of example (even though my book says dict is mutable): class SortedKeyDict(dict): def __new__(cls,