Package COM. yang. ex17; import Java. util. arraylist; import Java. util. arrays; import Java. util. list;/* Arrays: the tool class used to operate arrays * contains static methods * aslist: convert the array to the list set *****/public class arraydemo {public static void main (string [] ARGs) {// todo auto-generated method stub string [] arr = {"ABC", "DDD", "KKKK"}; // converts an array to a list set: /** you can use the collection idea to operate arrays * Note: changing an array into a set does not allow the addition or deletion of a set because the array length * is fixed. * Contains * Get * indexof * If added or deleted, an unsupported operation exception occurs. ** // ** if all elements in the array are of the basic data type, this array will be used as an element in the set. * if all elements in the array are objects, the array will become a set, the elements in the array are directly converted into elements in the Set *****/list <string> List = arrays. aslist (ARR); system. out. println (list. contains ("cc"); system. out. println (list);} public static Boolean mycontains (string [] arr, string key) {for (INT x = 0; x <arr. length; X ++) {If (ARR [X]. equals (key) {return true;} return True ;}} package COM. yang. ex17; import Java. util. arraylist; import Java. util. collection; import Java. util. collections; import Java. util. comparator; import Java. util. iterator; import Java. util. list; import Java. util. stack; import Java. util. treeset; import COM. yang. exspe01.treeset;/* collections: class used to operate the set *****/public class demo {public static void main (string ARGs []) {// sortdemo (); // maxdemo (); // B Inarysearchdemo (); // filldemo (); // replaceall (); // orderdemo (); shuffledemo ();} public static void sortdemo () {list <string> List = new arraylist <string> (); list. add ("ABCD"); list. add ("AAAAA"); list. add ("dddd"); list. add ("ppppp"); list. add ("Rrrr"); list. add ("llll"); system. out. println (list); collections. sort (list); system. out. println (list);} class srtlencomparator implements comparator <string> {public int Co Mpare (string S1, string S2) {If (s1.length ()> s2.length () {return 1;} If (s1.length () <s2.length () {return-1 ;} return 0 ;}} public static void binarysearchdemo () {list <string> List = new arraylist <string> (); list. add ("ABCD"); list. add ("AAAAA"); list. add ("dddd"); list. add ("ppppp"); list. add ("qrrrr"); list. add ("fdsfsllll"); collections. sort (list); system. out. println (list); int Index = collections. binarysear CH (list, "qrrrr"); system. out. println (INDEX);} public static void maxdemo () {list <string> List = new arraylist <string> (); list. add ("ABCD"); list. add ("AAAAA"); list. add ("dddd"); list. add ("ppppp"); list. add ("qrrrr"); list. add ("fdsfsllll"); collections. sort (list); system. out. println (list); string max = collections. max (list); system. out. println (max); collections. max (list); system. out. println (list);} public static voi D filldemo () {list <string> List = new arraylist <string> (); list. add ("ABCD"); list. add ("AAAAA"); list. add ("dddd"); list. add ("ppppp"); list. add ("qrrrr"); list. add ("fdsfsllll"); system. out. println (list); collections. fill (list, "PP"); // replace all elements in the set with system. out. println (list);} public static void replaceall () {list <string> List = new arraylist <string> (); list. add ("ABCD"); list. add ("AAAAA"); list. add ("dddd"); list. add ("Ppppp"); list. add ("qrrrr"); list. add ("fdsfsllll"); system. out. println (list); collections. replaceall (list, "AAAAA", "KK"); system. out. println (list); collections. reverse (list); system. out. println (list);} public static void orderdemo () {treeset <string> treeset = new treeset <string> (collections. reverseorder (); // reverse the treeset. add ("ABCD"); treeset. add ("AAAAA"); treeset. add ("dddd"); treeset. add ("ppppp"); treeset. add ("Qrrrr"); treeset. add ("fdsfsllll"); iterator <string> iterator = treeset. iterator (); While (iterator. hasnext () {system. out. println (iterator. next () ;}} class strcomparator implements comparator <string >{ public int compare (string S1, string S2) {// int num = s1.compareto (S1 ); // If (Num> 0) {// return-1; //} // If (Num <0) {// return 1; return s2.compareto (S1 );}} public static void shuffledemo () {// sort Lis randomly T <string> List = new arraylist <string> (); list. add ("ABCD"); list. add ("AAAAA"); list. add ("dddd"); list. add ("ppppp"); list. add ("qrrrr"); list. add ("fdsfsllll"); system. out. println (list); collections. shuffle (list); system. out. println (list);} // public static <t extends comparable <? Extends T> void sort (list <t> List) {//} // Arrays: used to operate the array}
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