Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.8k views
in Technique[技术] by (71.8m points)

what is logic behind this java code

I came across below java line and puzzled about its output. Can you please explain me logic behind this code

System.out.println((int)(char)(byte) -1);

Output:

65535
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Well, it's equivalent to:

byte b = -1;
char c = (char) b; // c = 'uFFFF' - overflow from -1
int i = c; // i = 65535

Really the explicit conversion to int in the original is only to make it call System.out.println(int) instead of System.out.println(char).

I believe the byte to char conversion is actually going through an implicit widening conversion first - so it's like this really:

byte b = -1;
int tmp = b; // tmp = -1
char c = (char) tmp; // c = 'uFFFF'

Does that help at all?


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...