Java Puzzlers笔记--puzzle 11: The last laugh "" 与''的区别
2007-03-04 10:30
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public class LastLaugh{
public static void main(String[] args){
System.out.println("H" + "a");
System.out.println('H' + 'a');
}
}
Solution:
显示:Ha169
因为'H' + 'a' 不是连接2个字符,而是把H和a转ASC码,再进行加法运算;
TID:
The + operator performs string concatenation if and only if at least one of its operands is of type String;
Correctly:
StringBuffer sb = new StringBuffer();
sb.append('H');
sb.append('a');
System.out.println(sb);
or:
System.out.println("" + 'H' + 'a' );
or:
System.out.println("%c%c", 'H', 'a'); // in release 5.0
public static void main(String[] args){
System.out.println("H" + "a");
System.out.println('H' + 'a');
}
}
Solution:
显示:Ha169
因为'H' + 'a' 不是连接2个字符,而是把H和a转ASC码,再进行加法运算;
TID:
The + operator performs string concatenation if and only if at least one of its operands is of type String;
Correctly:
StringBuffer sb = new StringBuffer();
sb.append('H');
sb.append('a');
System.out.println(sb);
or:
System.out.println("" + 'H' + 'a' );
or:
System.out.println("%c%c", 'H', 'a'); // in release 5.0
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