Java String
String widely used Java programming again, strings belong to the object to provide a String class to create and manipulate strings
- Creating strings
- String length
- Connection String
- Create a format string
- String Methods
Creating strings
Syntax:String str ="hello world !;
And other objects, you can use keywords and construction methods to create Stirng objects, String There are 11 constructors provide different parameters to initialization string.
Examples
public class StringDemo{
public static void main(String[] args) { char[] helloArr={'n','i','h','a','o'}; String helloStr = new String(helloArr); System.out.println(helloStr); } }
Note : String class is not the hundred years, once created, the value can not be changed.
String length
String class by a method length (), it returns the number of characters contained in the string objects.
helloStr.length();
Connection String
String provided a method of connecting two strings:
-
concat();
stirng1.concat(string2) -
More often by "+" connected to concatenate strings
"Name"+" : "+"张三"
Create a format string
Method format Stirng static class () can be used to create a formatted string reusable, and not just for printout.
Examples
String FS ;
FS = String . The format ( "float variable value" + "% F, the value of the integer variable" + "D%, the string variable value" + "% S" , floatVar , IntVar , strinVar ) ;
String Methods
| Numbering | The method described |
|---|---|
| 1 | char cahrAt (int index) Returns the char value at the specified index |
| 2 | int compareTo (Object o) comparing the string to another object |
| 3 | int compareTo (String anotherString) lexicographically compare two strings |
| 4 | int compareTolgnoreCase (String str) lexicographically compare two strings, ignoring case |
| 5 | String concat (Object o) the specified string is connected to this end of the string |
| 6 | boolean contentEquals (StringBuffer sb) if and only if the specified character string when the character has the same sequence StringBuffer returns true |
| 7 | static String copyValueOf (char [] data ) array specified String representing the character sequence |
| 8 | static String copyValueOf (char [] data , int offset, int count) array specified sequence of characters representing a String |
| 9 | boolean endsWith (String suffix) Tests if this string ends with the specified suffix |
| 10 | boolean equals (Object anObject) this string with the development of object comparison |
| 11 | boolean equalsgnoreCase (String anotherString) this String comparison with another String, ignoring case considerations |
| 12 | byte [] the getBytes () using the platform's default character set encoding this String is byte sequence, and stores a new byte array to the result |
| 13 | byte [] getBytes (String charsetName) the specified character set coding this String is byte sequence, and storing the result into a new byte array |
| 14 | void getChars (int srcBegin, int srcEnd , char [] dst, int dstBegin) the string from the string copied to the target character array |
| 15 | int hashCode Returns a hash code string |
| 16 | int indexOf (int ch) Returns the index of the specified character in this string of the first occurrence of |
| 17 | int indexOf (int ch, int fromIndex ) Returns the index at a specified character appears in this string for the first time, start the search from the specified index |
| 18 | int indexOf (String str) Returns the index of the substring occurs in the first time this string |
| 19 | int indexOf (String str, int fromIdex ) Returns the substring position in the first occurrence of this string, starting at the specified index |
| 20 | String intern () return a String object normalized display |
| 21 | int lastIndexOf (int ch) Returns the specified character position in this string of the last displayed |
| 22 | int lastIndexOf (int ch, int fromIndex ) Returns the position of the last occurrence of the specified character at the specified index |
| 23 | int lastIndexOf (String str) Returns the substring index within this string of the rightmost occurrence of |
| 24 | int lastIndexOf (String str, int fromIndex ) Returns the index of the last substring in this string appears, starting at the specified index reverse lookup |
| 25 | int length() 返回此字符串的长度。 |
| 26 | boolean matches(String regex) 告知此字符串是否匹配给定的正则表达式 |
| 27 | boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len) 测试两个字符串区域是否相等 |
| 28 | boolean regionMatches(int toffset, String other, int ooffset, int len) 测试两个字符串区域是否相等 |
| 29 | String replace(char oldChar, char newChar) 返回一个新的字符串，它是通过用 newChar 替换此字符串中出现的所有 oldChar 得到的 |
| 30 | String replaceAll(String regex, String replacement) 使用给定的 replacement 替换此字符串所有匹配给定的正则表达式的子字符串 |
| 31 | String replaceFirst(String regex, String replacement) 使用给定的 replacement 替换此字符串匹配给定的正则表达式的第一个子字符串 |
| 32 | String[] split(String regex) 根据给定正则表达式的匹配拆分此字符串 |
| 33 | String[] split(String regex, int limit) 根据匹配给定的正则表达式来拆分此字符串 |
| 34 | boolean startsWith(String prefix) 测试此字符串是否以指定的前缀开始 |
| 35 | boolean startsWith(String prefix, int toffset) 测试此字符串从指定索引开始的子字符串是否以指定前缀开始 |
| 36 | CharSequence subSequence(int beginIndex, int endIndex) 返回一个新的字符序列，它是此序列的一个子序列 |
| 37 | String substring(int beginIndex, int endIndex) 把这个字符串和另一个对象比较 |
| 38 | int compareTo(Object o) 返回一个新字符串，它是此字符串的一个子字符串 |
| 39 | char[] toCharArray() 将此字符串转换为一个新的字符数组 |
| 40 | String toLowerCase() 使用默认语言环境的规则将此 String 中的所有字符都转换为小写 |
| 41 | String toLowerCase(Locale locale) 使用给定 Locale 的规则将此 String 中的所有字符都转换为小写 |
| 42 | String toString() 返回此对象本身（它已经是一个字符串！） |
| 43 | String toUpperCase() 使用默认语言环境的规则将此 String 中的所有字符都转换为大写 |
| 44 | String toUpperCase(Locale locale) 使用给定 Locale 的规则将此 String 中的所有字符都转换为大写 |
| 45 | String trim() 返回字符串的副本，忽略前导空白和尾部空白 |
| 46 | static String valueOf(primitive data type x) 返回给定data type类型x参数的字符串表示形式 |