String类题目methods总结

用到的Class和methods：

1. 类String

(1)charAt

String s;

s.charAt(i);

(2)split

分割一个String用split:

public String[] split(String regex)

Regex	Result
:	{ "boo", "and", "foo" }
o	{ "b", "", ":and:f" }

 

(3) trim删除空格

public String trim()

Returns a copy of the string, with leading and trailing whitespace omitted.

 

 

(4)equals

public boolean equals(Object anObject)

Compares this string to the specified object. The result is true if and only if the argument is not null and is a String object that represents the same sequence of characters as this object.

example: http://www.cnblogs.com/hygeia/p/4830911.html

 

 

2. 类Character: http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html

用法类似Character.isLetterOrDigit(s.charAt(i))

（1） isLetterOrDigit(char ch)

Determines if the specified character is a letter or digit.

Return static boolean

example: http://www.cnblogs.com/hygeia/p/4830949.html

 

（2） toLowerCase(char ch)

Converts the character argument to lowercase using case mapping information from the UnicodeData file.

Return static char

 

（3）isWhitespace(char ch)

Determines if the specified character is white space according to Java.

 

（4）isDigit(char ch)

Determines if the specified character is a digit.

 

 

3. 类StringBuilder：http://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html

 

(1) append(char c)

Appends the string representation of the char argument to this sequence.

return StringBuilder

 

(2)toString()

Returns a string representing the data in this sequence.

return String

 

4. 转化

(1) Integer to String


• String.valueOf(number) (my preference)
• "" + number (I don't know how the compiler handles it, perhaps it is as efficient as the above)
• Integer.toString(number)

(2) String to Integer

　　Integer x = Integer.valueOf(str);
　　// or
　　int y = Integer.parseInt(str);