Common methods of the String class:
int length (): returns the length of a string: return value.length
char the charAt (int index) : Returns the character return value [index] index of a
boolean isEmpty (): determining whether an empty string is: return value.length = 0 =
string toLowerCase (): use the default locale, all characters are converted to lowercase string
string toUpperCase (): use the default locale, string converts all characters to uppercase
string trim (): returns a copy of the string , ignores leading and trailing whitespace
boolean equals (Object obj): compare string contents are the same
boolean equalsIgnoreCase (string anotherString): similar to the equals method, the content is the same as comparing strings ignoring case
String concat (String str): The specified string is connected to this end of the string. Is equivalent to a "+"
int the compareTo (String anotherString): Compares two strings size
String substring (int beginIndex): Returns a new string, this string which is taken from the start to the last beginIndex a child string. (To the current character in the string)
String the substring (int beginIndex, int endIndex): Returns a new string, this string which is taken to start from beginIndex endIndex (not included) of a substring.
@Test public void test2(){ String s1="HelloWorld"; String s2="helloworld"; System.out.println (s1.equals (S2)); // if the contents of the string comparison same System.out.println (s1.equalsIgnoreCase (S2)); // the comparison string is the same as the contents ignore case String s3 = "ABC" ; S4 String = s3.concat ( "DEF"); // the specified string is connected to the end of the string System.out.println (s4); String s5="abc"; String s6=new String("abe"); System.out.println (s5.compareTo (S6)); // compare the size of the two strings S7 String = "I am a chicken dish java ohh ohh hum" ; S8 String = s7.substring (2); // start from a position intercepting the string System.out.println (s8); S9 String = s7.substring (3,12); // start capturing from a position to the end position System.out.println (s9); } @Test public void test1(){ String s1="HelloWrold"; System.out.println(s1.length()); System.out.println(s1.charAt(0)); System.out.println(s1.charAt(9)); System.out.println(s1.isEmpty()); S2 String = s1.toLowerCase (); // character lowercase System.out.println ( "s1 is not made or the original" + s1); // or the original string s1 immutable System.out. println ( "after the change lowercase string:" + S2); // string lowercase after change String s3=" he llo world "; S4 String = s3.trim (); // end-users to register for the blank usually account when System.out.println ( "------" + s3 + "----------" ); // go blank before System.out.println ( "------" + S4 + "----------"); // the table to empty }
boolean endsWith (String suffix): Tests if this string ends with the specified suffix
boolean startsWith (String prefix): Tests if this string to the specified prefix beginning
boolean startsWith (String prefix, int toffset ): Tests if this string from the specified whether substring based index starts with the specified prefix
boolean contains (CharSequence s): if and only if this string contains the specified sequence of char values, return to true
int indexOf (String STR): Returns the index of the substring in the first occurrence of this string
int indexOf (string str, int fromIndex): returns the substring index within this string of the first occurrence, starting at the specified index
int lastIndexOf (string str): returns a substring in this string of the rightmost index appear at the
int lastIndexOf (string str, int fromIndex ): returns a substring index within this string of the last occurrence, starting at the specified index of reverse search
Note: indexOf and lastIndexOf method returns -1 if not found all
@Test public void test3(){ Str1 String = "HelloWorld" ; // test whether this string ending specified suffix Boolean B1 = str1.endsWith ( "RLD" ); System.out.println(b1); boolean b2=str1.startsWith("he"); System.out.println(b2); // test whether this string substring from the specified index starting with the prefix specified Boolean B3 = str1.startsWith ( "LL", 2 ); System.out.println(b3); String str2="wor"; System.out.println (str1.contains (str2)); // if str1 contains str2 will return to true System.out.println (str1.indexOf ( "lol" )); System.out.println(str1.indexOf("lo",5)); String str3 = "hellorworld"; System.out.println(str3.lastIndexOf("or")); System.out.println(str3.lastIndexOf("or",6)); // What happens next, indexOf (str) and lastIndexOf (str) return the same value? // Case 1: there is only one str. Scenario 2: There is no str }
Alternatively:
String Replace (oldChar char, char newChar): Returns a new string, which is obtained by replacing all oldChar this string with newChar obtained.
String replace (CharSequence target, CharSequence replacement ): specified literal replacement sequence replacement substring of this string literal match all of the target sequence.
String replaceAll (String regex, String replacement ): given this string of all replacement alternative matches the given regular expression substring.
String replaceFirst (String regex, String replacement ): using the given first sub-alternative replacement of this string matches the given regular expression.
Matching:
boolean The matches (String regex): Tell whether this string matches the given regular expression.
Slice:
String [] Split (String REGEX): The given regular expression matching split this string.
String [] split (String regex, int limit): According to match a given regular expression to split this string, no more than a limit, if exceeded, all the rest are placed in the last element.
@Test public void test4(){ Str String = "I am a java dish chicken dish chicken dishes chicken dish chicken dishes chicken" ; Str2 String = str.replace ( 'vegetables', 'weak' ); System.out.println(str); System.out.println(str2); Str3 String = str.replace ( "I", "you are" ); System.out.println(str); System.out.println(str3); System.out.println("*************************"); Str1 String = "12hello34world5java7891mysql456" ; // digital string replaced, that if there is the beginning and end result, then remove String string = str1.replaceAll ( "\\ d +", ",") replaceAll ( ". ^, |, $ "," " ); System.out.println(string); System.out.println("*************************"); str1 = "12345" ; // determines whether all the string str digital composition, that is 1-n digits Boolean The matches str1.matches = ( "\\ + D" ); System.out.println(matches); Tel String = "0571-4534289" ; // determines whether this is a fixed telephone Hangzhou Boolean Result = tel.matches ( "0571 - \\ D {7, 8}" ); System.out.println(result); System.out.println("*************************"); str1 = "hello|world|java"; String[] strs = str1.split("\\|"); for (int i = 0; i < strs.length; i++) { System.out.println(strs[i]); } System.out.println(); str2 = "hello.world.java"; String[] strs2 = str2.split("\\."); for (int i = 0; i < strs2.length; i++) { System.out.println(strs2[i]); } }
Complete code:
package String; import org.junit.Test; /** * Created with IntelliJ IDEA. * User: Guo Jinrong * Date: 2020/3/7 0007 * Time: 22:27 * E-mail: [email protected] * Class Description: */ public class StringMethodTest { /* replace: String replace (char oldChar, char newChar): Returns a new string, which is obtained by replacing all oldChar this string with newChar obtained. String replace (CharSequence target, CharSequence replacement): specified literal replacement sequence replacement substring of this string literal match all of the target sequence. String replaceAll (String regex, String replacement): replacing the given replacement string matches all given regular expression substring. String replaceFirst (String regex, String replacement): using the given first sub-alternative replacement of this string matches the given regular expression. match: boolean matches (String regex): inform this string matches the given regular expression. slice: String [] split (String regex): The given regular expression matching split this string. String [] split (String regex, int limit): According to match a given regular expression to split this string, no more than a limit, if exceeded, all the rest are placed in the last element. */ @Test public void test4 () { Str String = "I am a java dish chicken dish chicken dishes chicken dish chicken dishes chicken" ; Str2 String = str.replace ( 'vegetables', 'weak' ); System.out.println(str); System.out.println(str2); Str3 String = str.replace ( "I", "you are" ); System.out.println(str); System.out.println(str3); System.out.println("*************************"); Str1 String = "12hello34world5java7891mysql456" ; // digital string replaced, that if there is the beginning and end result, then remove String string = str1.replaceAll ( "\\ d +", ",") replaceAll ( ". ^, |, $ "," " ); System.out.println(string); System.out.println("*************************"); str1 = "12345" ; // determines whether all the string str digital composition, that is 1-n digits Boolean The matches str1.matches = ( "\\ + D" ); System.out.println(matches); Tel String = "0571-4534289" ; // determines whether this is a fixed telephone Hangzhou Boolean Result = tel.matches ( "0571 - \\ D {7, 8}" ); System.out.println(result); System.out.println("*************************"); str1 = "hello|world|java"; String[] strs = str1.split("\\|"); for (int i = 0; i < strs.length; i++) { System.out.println(strs[i]); } System.out.println(); str2 = "hello.world.java"; String[] strs2 = str2.split("\\."); for (int i = 0; i < strs2.length; i++) { System.out.println(strs2[i]); } } /* boolean endsWith (String suffix): Tests if this string ends with the specified suffix boolean startsWith (String prefix): Tests if this string to the specified prefix beginning boolean startsWith (String prefix, int toffset): Tests if this string substring from the specified whether the index starts with the specified prefix boolean contains (CharSequence s): if and only if this string contains the specified sequence of char values, return true int indexOf (String str): Returns the index of the substring in the first occurrence of the string int indexOf (String str, int fromIndex): Returns the substring index within this string of the first occurrence, starting at the specified index int lastIndexOf (String str): Returns a substring index within this string of the rightmost occurrence int lastIndexOf (String str, int fromIndex): Returns a substring index within this string of the last occurrence, starting at the specified index of reverse search Note: indexOf and lastIndexOf method returns -1 if not found all */ @Test public void test3 () { Str1 String = "HelloWorld" ; // test whether this string ending specified suffix Boolean B1 = str1.endsWith ( "RLD" ); System.out.println(b1); boolean b2=str1.startsWith("he"); System.out.println(b2); // test whether this string substring from the specified index starting with the prefix specified Boolean B3 = str1.startsWith ( "LL", 2 ); System.out.println(b3); String str2="wor"; System.out.println (str1.contains (str2)); // if str1 contains str2 will return to true System.out.println (str1.indexOf ( "lol" )); System.out.println(str1.indexOf("lo",5)); String str3 = "hellorworld"; System.out.println(str3.lastIndexOf("or")); System.out.println(str3.lastIndexOf("or",6)); // What happens next, indexOf (str) and lastIndexOf (str) return the same value? // Case 1: there is only one str. Scenario 2: There is no str } /* int length (): returns the length of a string: return value.length char charAt (int index): Returns the index of the character of a return value [index] boolean isEmpty (): determining whether an empty string is: return value.length == 0 String toLowerCase (): Use the default locale, String Converts all characters to lowercase String toUpperCase (): Use the default locale, all characters are converted to uppercase String String trim (): Returns a string copy ignores leading and trailing whitespace boolean equals (Object obj): compare the contents of the string are the same boolean equalsIgnoreCase (String anotherString): Similar to the equals method, the content is the same as comparing strings ignoring case String concat (String str): The specified string is connected to this end of the string. It is equivalent to using the "+" int compareTo (String anotherString): compare the size of two strings String substring (int beginIndex): Returns a new string, this string which is taken from the start to the last beginIndex a substring. String substring (int beginIndex, int endIndex): Returns a new string, which is taken from this string starts beginIndex to endIndex (not included) of a substring. */ @Test public void test2 () { String s1="HelloWorld"; String s2="helloworld"; System.out.println (s1.equals (S2)); // if the contents of the string comparison same System.out.println (s1.equalsIgnoreCase (S2)); // the comparison string is the same as the contents ignore case String s3 = "ABC" ; S4 String = s3.concat ( "DEF"); // the specified string is connected to the end of the string System.out.println (s4); String s5="abc"; String s6=new String("abe"); System.out.println (s5.compareTo (S6)); // compare the size of the two strings S7 String = "I am a chicken dish java ohh ohh hum" ; S8 String = s7.substring (2); // start from a position intercepting the string System.out.println (s8); S9 String = s7.substring (3,12); // start capturing from a position to the end position System.out.println (s9); } @Test public void test1(){ String s1="HelloWrold"; System.out.println(s1.length()); System.out.println(s1.charAt(0)); System.out.println(s1.charAt(9)); System.out.println(s1.isEmpty()); S2 String = s1.toLowerCase (); // character lowercase System.out.println ( "s1 is not made or the original" + s1); // or the original string s1 immutable System.out. println ( "after the change lowercase string:" + S2); // string lowercase after change String s3=" he llo world "; S4 String = s3.trim (); // end-users to register for the blank usually account when System.out.println ( "------" + s3 + "----------" ); // go blank before System.out.println ( "------" + S4 + "----------"); // the table to empty } }