Topic: Is a Java String really immutable?

+Anonymous A — 12.6 years ago #31,485

We all know that String is immutable in Java, but check the following code:

String s1 = "Hello World";  

String s2 = "Hello World";  

String s3 = s1.substring(6);  

System.out.println(s1); // Hello World  

System.out.println(s2); // Hello World  

System.out.println(s3); // World  



Field field = String.class.getDeclaredField("value");  

field.setAccessible(true);  

char[] value = (char[])field.get(s1);  

value[6] = 'J';  

value[7] = 'a';  

value[8] = 'v';  

value[9] = 'a';  

value[10] = '!';  



System.out.println(s1); // Hello Java!  

System.out.println(s2); // Hello Java!  

System.out.println(s3); // World

Why does this program operate like this? Why is the value of s1 and s2 changed and not changed for s3?

Well?

C͙̱̪̦͎͖i̼̜̮͓ao̬̼,̘͈͇̗̞ ̰T͕͔̫̦͔͍h͉̲͍̠̭e͎̪̖͕̲̞̭ ͔͓̭̰̘D̥͓̘o̝̖͍̩̰͈c̭̳͈̗t͈͉̰͉̞o̞͔̥r.̦̦̙̼͉͍͕

Poll option	Votes	Percentage	Graph
Sprite.	-	0%
Boners.	-	0%

+Anonymous B — 12.6 years ago, 1 minute later[T] [B] #362,955

Hello World

·Anonymous A (OP) — 12.6 years ago, 1 minute later, 3 minutes after the original post[T] [B] #362,956

@previous (B)
> mad as hell

C̩̳̼̤̭̞̪i͎a̗̹̜̝̪o̹̺,̭̟ ͖̩T̥͇̪h̙̺͈̮͓̩ͅe̹̼ͅ D͓̮̙̞̗̹̣o̮̫̗̝̘ct̰̺ͅo͙r.̥̲̳̖

+Anonymous C — 12.6 years ago, 1 minute later, 4 minutes after the original post[T] [B] #362,957

no1 cars

·Anonymous B — 12.6 years ago, 9 minutes later, 14 minutes after the original post[T] [B] #362,958

@362,956 (A)
Field field = mad

+Anonymous D — 12.6 years ago, 7 hours later, 7 hours after the original post[T] [B] #363,043

Not doing your Java homework for you.

+Anonymous E — 12.6 years ago, 1 hour later, 8 hours after the original post[T] [B] #363,052

Want my notes?

+The Doctor !7MHPahvoGY — 12.6 years ago, 11 minutes later, 8 hours after the original post[T] [B] #363,055

@OP

Get laid, poindexter.

+Anonymous G — 12.6 years ago, 3 hours later, 12 hours after the original post[T] [B] #363,106

java sucks, i prefer c#
t(-___-t)

+Anonymous H — 12.6 years ago, 37 minutes later, 12 hours after the original post[T] [B] #363,108

@363,055 (The Doctor !7MHPahvoGY)

> Get laid, poindexter.

-----------
As a doctor, I support The Doctor's suicide.

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