Java Learning Lesson 30th (often using object APIs)-String class: Class method Exercises

Intern method

public class Main{public static void Main (string[] args) {string str1 = new String ("ASD"); String str2 = Str1.intern ();/* string constant in the pool, returns a string without creating a */system.out.println (STR2); System.out.println (str1 = = str2);}}

Exercise 1: Sorting a string array

Import java.util.scanner;/* * Given an array of strings, sorted ascending by dictionary order */public class main {public static void Main (string[] args) {Stringsort () ;} public static void Stringsort () {string[] str = new STRING[10]; Scanner in = new Scanner (system.in), for (int i = 0; i < str.length; i++) {Str[i] = In.nextline ();} System.out.println (str.length); for (int i = 0, i < str.length-1; i++) {for (int j = 0; J < str.length-1-I; J + +) {if (Str[j].compareto (Str[j + 1]) > 0) {String t = str[j];str[j] = str[j + 1];str[j + 1] = t;}}} for (String istring:str) {System.out.println (istring);}}}

Exercise 2: Count the number of times a substring appears in a string

IndexOf's application, record the current subscript a. And then from the A + substring length continued after indexof, using the loop to achieve this function

Import java.util.scanner;/* * Number of occurrences of a substring in a string */public class main {public static void Main (string[] args) {count ()} public static void Count () {String str = "ABCDEFABCGHIABCSDABCHZABC"; int num = 0,WZ = 0;for (int i = 0; i < str.length ( ); i++) {int t = str.indexof ("abc", WZ), if (t!=-1) {wz = t+ "abc". Length (); num++;} else break;} SYSTEM.OUT.PRINTLN (num);}}

Exercise 3: The maximum number of identical strings for a two string

Import java.util.scanner;/* * The longest common substring in two strings */public class main {public static void Main (string[] args) {string tstring = Compare (); System.out.println (tstring);} public static string compare () {string str1 = "VBABCDEFGSDFG"; String str2 = "ASDABCDEFGDF"; int mlen = Str1.length (); int zlen = Str2.length (); int len = (Mlen > Zlen)?
zlen:mlen;//find a shorter string, the maximum public length will not exceed the len//common substring may be present in the middle for (int i = 0; i < len; i++)//control maximum length {for (int j = 0, k = len-i; k <= Len; k++, J + +)//J control several satisfies, K control substring the last element subscript does not cross the bounds {String sub = str2.substring (j, k); if (Str1.contains (sub)) return sub;}} return null;}}

Exercise 4: Remove both spaces (simulate trim method)

public class Main {public static void main (string[] args) {string string = "    ASD fs FG H   "; int st = 0,en = string. Length () -1;for (; st<=en && String.charat (st) = = "; st++); for (; st<=en && string.charat (en) = ="; en--); String sub = string.substring (St, en+1); System.out.println (sub);}}

Java Learning Lesson 30th (often using object APIs)-String class: Class method Exercises