String class: can not be modified (with a final modification)
(1) Constructor
public String () public String ( byte [] bytes): the byte to a string array to a public String ( byte [] bytes, int index, int length): a part of the byte array translated into strings public String ( char [] value, int index, int COUNT): a part of the array of characters is translated into strings public string (string Original): a string object initialization newly created, it represents the same sequence of characters parameter; in other words, the newly created string is a copy of the parameter string.
(2) The method of Example
1) determining function
public Boolean the equals (Object anObject) determines whether the character string as public Boolean equalsIgnoreCase (String anotherString) determines whether the same string, ignoring case public Boolean the contains (CharSequence S) which determines whether a string contains the string, CharSequence is an interface, String class implements the interface, so the types of parameters can be passed Sting public Boolean whether startsWith (string prefix) to nothing at the beginning of the string is determined public Boolean endsWith (string suffix) determines whether the end of the string in what public Boolean isEmpty () determines string is empty string
2) acquisition function
int length (): Get the length of the string char the charAt ( int index): Gets a character specified index int the indexOf ( int CH): Get the specified character appears in the index of the first string int the indexOf (String STR) : returns the string index within this string of the first occurrence of int indexOf ( int CH, int fromIndex): returns the character index of the first occurrence of the specified position in this string int indexOf (string str , int returns the index of the string in the string after the first occurrence of the specified location: fromIndex) int position lastIndexOf () appears in the last The substring String ( int Start): Start from the specified location string taken, not by default to the end The substring String ( int Start, int End): starting at the specified position to a specified position of the end of characters, taken FIG.
3) conversion function
byte [] the getBytes (): the string into a byte array char [] toCharArray (): converts a string to a character array static String valueOf ( char [] CHS): the array of characters translated into strings static String valueOf ( int I): the int type data into a string Note: valueOf String class method can be any type of data into a string String toLowerCase (): string to lower case String toUpperCase (): turn a string to uppercase String concat (String str): The string concatenation, and only string concatenation. + When spliced string may be any type
4) Other
public String Replace ( char occurrences of oldChar in, char newChar) // replacement character public String Replace (CharSequence target, CharSequence Replacement) // replacement string String TRIM (); // longitudinal removing spaces public int the compareTo (String anotherString) // comparison, were compared according to the ASCII code table public int compareToIgnoreCase (String str) // Compare
About compareTo () method: character by character as the difference when the difference is zero when compared to compare the next character to know the end.
String s1 = "abc"; String s2 = "ABC"; int b = s1.compareTo(s2); System.out.println(b); //32 ==> 'a'-'A' ==> 97-65=32
public int compareTo(String anotherString) { int len1 = value.length; int len2 = anotherString.value.length; int lim = Math.min(len1, len2); char v1[] = value; char v2[] = anotherString.value; int k = 0; while (k < lim) { char c1 = v1[k]; char c2 = v2[k]; if (c1 != c2) { return c1 - c2; } k++; } return len1 - len2; }
StringBuffer class: You can modify, thread-safe, the parent class is AbstractStringBuilder.
Internal StringBuffer class has a character buffer array, the array is actually operated. And String class also has a character array, but the array with a final modification, and initialized in the constructor, it can not be modified.
(1) Constructor
public the StringBuffer (): null constructor parameters, a default capacity is 16 public the StringBuffer ( int Capacity): specified capacity public the StringBuffer (String STR): the given initial character string array
(2) a method of adding
public synchronized StringBuffer append public synchronized StringBuffer insert
(3) Delete method
deleteCharAt ( int index) Delete character at the specified index the Delete ( int Start, int End): delete the beginning to the end position of the character
(4) inversion method
public synchronized StringBuffer reverse()
(5) intercepting function, the return value is String
public String the substring ( int Start): intercepted from the specified position to the end of public String the substring ( int Start, int End): taken at the specified position to the end position, comprising a start position, end position is not included
(6) String and StringBuffer conversion
String transfer StringBuffer: . 1) constructor new new StringBuffer (String STR) 2 the append method) using the StringBuffer StringBuffer转String: 1) String class constructor new new String (StringBuffer S) 2 ) The method of StringBuffer toString substring methods. 3) of StringBuffer