java char encoding length should always be x times 2?

up vote
2
down vote

favorite

java internal encoding for chars are UTF-16 right? While all ASCII uses 2 bytes encoding, then I expect:

     String h="hello"; 

     System.out.println(h.codePointCount(0,h.length())); 

     System.out.println(h.length());

to print 10 and 5, But in fact it prints 5, 5.

Where did I get wrong?

asked Nov 20 at 12:06

Troskyvs

2,25011026

There is the answer for this question stackoverflow.com/questions/5078314/…
– Centos
Nov 20 at 12:16

codePointCount basically is a more exact version of length that works correctly for surrogate pairs. For ASCII characters (more generally BMP characters) there is no difference.
– Henry
Nov 20 at 12:41

add a comment |

up vote
2
down vote

favorite

java internal encoding for chars are UTF-16 right? While all ASCII uses 2 bytes encoding, then I expect:

     String h="hello"; 

     System.out.println(h.codePointCount(0,h.length())); 

     System.out.println(h.length());

to print 10 and 5, But in fact it prints 5, 5.

Where did I get wrong?

asked Nov 20 at 12:06

Troskyvs

2,25011026

There is the answer for this question stackoverflow.com/questions/5078314/…
– Centos
Nov 20 at 12:16

codePointCount basically is a more exact version of length that works correctly for surrogate pairs. For ASCII characters (more generally BMP characters) there is no difference.
– Henry
Nov 20 at 12:41

add a comment |

up vote
2
down vote

favorite

java internal encoding for chars are UTF-16 right? While all ASCII uses 2 bytes encoding, then I expect:

     String h="hello"; 

     System.out.println(h.codePointCount(0,h.length())); 

     System.out.println(h.length());

to print 10 and 5, But in fact it prints 5, 5.

Where did I get wrong?

asked Nov 20 at 12:06

Troskyvs

2,25011026

java internal encoding for chars are UTF-16 right? While all ASCII uses 2 bytes encoding, then I expect:

     String h="hello"; 

     System.out.println(h.codePointCount(0,h.length())); 

     System.out.println(h.length());

to print 10 and 5, But in fact it prints 5, 5.

Where did I get wrong?

java encoding char

asked Nov 20 at 12:06

Troskyvs

2,25011026

asked Nov 20 at 12:06

Troskyvs

2,25011026

asked Nov 20 at 12:06

Troskyvs

2,25011026

asked Nov 20 at 12:06

Troskyvs

2,25011026

asked Nov 20 at 12:06

Troskyvs

2,25011026

There is the answer for this question stackoverflow.com/questions/5078314/…
– Centos
Nov 20 at 12:16

codePointCount basically is a more exact version of length that works correctly for surrogate pairs. For ASCII characters (more generally BMP characters) there is no difference.
– Henry
Nov 20 at 12:41

add a comment |

There is the answer for this question stackoverflow.com/questions/5078314/…
– Centos
Nov 20 at 12:16

codePointCount basically is a more exact version of length that works correctly for surrogate pairs. For ASCII characters (more generally BMP characters) there is no difference.
– Henry
Nov 20 at 12:41

There is the answer for this question stackoverflow.com/questions/5078314/…
– Centos
Nov 20 at 12:16

codePointCount basically is a more exact version of length that works correctly for surrogate pairs. For ASCII characters (more generally BMP characters) there is no difference.
– Henry
Nov 20 at 12:41

add a comment |

1 Answer
1

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oldest

votes

up vote
2
down vote

accepted

Try

String h="hell😀";

System.out.println(h.codePointCount(0,h.length())); 

System.out.println(h.length());

it prints 5, 6.

'😀' is presented by two code units, each of 'h', 'e', 'l', 'l' - by one.

And about UTF-16: "The encoding is variable-length, as code points are encoded with one or two 16-bit code units..."

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

In case it's not clear, the question arises from confusing Unicode codepoints with UTF-16 code units. Codepoints are not encoded.
– Tom Blodget
Nov 20 at 14:43

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

up vote
2
down vote

accepted

Try

String h="hell😀";

System.out.println(h.codePointCount(0,h.length())); 

System.out.println(h.length());

it prints 5, 6.

'😀' is presented by two code units, each of 'h', 'e', 'l', 'l' - by one.

And about UTF-16: "The encoding is variable-length, as code points are encoded with one or two 16-bit code units..."

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

In case it's not clear, the question arises from confusing Unicode codepoints with UTF-16 code units. Codepoints are not encoded.
– Tom Blodget
Nov 20 at 14:43

add a comment |

up vote
2
down vote

accepted

Try

String h="hell😀";

System.out.println(h.codePointCount(0,h.length())); 

System.out.println(h.length());

it prints 5, 6.

'😀' is presented by two code units, each of 'h', 'e', 'l', 'l' - by one.

And about UTF-16: "The encoding is variable-length, as code points are encoded with one or two 16-bit code units..."

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

In case it's not clear, the question arises from confusing Unicode codepoints with UTF-16 code units. Codepoints are not encoded.
– Tom Blodget
Nov 20 at 14:43

add a comment |

up vote
2
down vote

accepted

Try

String h="hell😀";

System.out.println(h.codePointCount(0,h.length())); 

System.out.println(h.length());

it prints 5, 6.

'😀' is presented by two code units, each of 'h', 'e', 'l', 'l' - by one.

And about UTF-16: "The encoding is variable-length, as code points are encoded with one or two 16-bit code units..."

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

Try

String h="hell😀";

System.out.println(h.codePointCount(0,h.length())); 

System.out.println(h.length());

it prints 5, 6.

'😀' is presented by two code units, each of 'h', 'e', 'l', 'l' - by one.

And about UTF-16: "The encoding is variable-length, as code points are encoded with one or two 16-bit code units..."

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

answered Nov 20 at 12:54

Anatoly Samoylenko

32115

In case it's not clear, the question arises from confusing Unicode codepoints with UTF-16 code units. Codepoints are not encoded.
– Tom Blodget
Nov 20 at 14:43

add a comment |

In case it's not clear, the question arises from confusing Unicode codepoints with UTF-16 code units. Codepoints are not encoded.
– Tom Blodget
Nov 20 at 14:43

In case it's not clear, the question arises from confusing Unicode codepoints with UTF-16 code units. Codepoints are not encoded.
– Tom Blodget
Nov 20 at 14:43

add a comment |

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