KMP Algorithm for Java implementation

 Packagedatastructure;Importjava.util.ArrayList;Importjava.util.List;//implementation of KMP algorithm//The following code is written in conjunction with the Freedom Data Public classDMPtest1 {Private intnext[]; PrivateString Target;//Main string    PrivateString pattern;//Sub-string    Char[] t;//Main string Character    Char[] p;//substring characters    Private StaticList<integer>list;  PublicDMPtest1 () {} PublicDMPtest1 (String pattern,string target) { This. Pattern =pattern;  This. target =Target; P= This. Pattern.tochararray (); T= This. Target.tochararray (); //list = new arraylist<integer> (); //Initializes a collection to hold the index of the matching substring in the main stringNext = This. Getnextarray ( This. pattern);//accept returned arrays that are already well-received            }         Public voidDisplaynext () {//Print Next Array         for(inti=0;i<next.length; i++) {System.out.print (next[i]); }            }         PublicList<integer>Gettargetindex () {List<Integer> list =NewArraylist<integer>(); intNum=0; inti = 0;//Main string Target subscript        intj = 0;//Sub-string pattern subscript        if(t.length>=p.length) { while(i<t.length) {//because the subscript of the main string is constant, only the match exceeds his own length and jumps out of the loop .                                if(p[j]==T[i]) {num++;//For the first time, then num clear 0.J + +; I++; //System.out.println ("a target has been found" +j+p.length);                        if(j>p.length-1) {//if it's the last number.List.add (i-J);//adds a matching string to the list in the main string position (index of the first character)J=0; //indicates that a substring has been matched//J is already equal to the next subscript of the last subscript of the P array.                        }                    }Else {                        //two characters don't match.//the new index of J is directly equal to NEXT[J] The conclusion is written on the paper .                                                if(num==0) {J=0; //the first time is unequal, then I need to self-addi++; //This structure should be careful, be sure to write in front of the next if!                         }                                            if(num>0) {                                                        //The description is not the first time inequality, then the main string subscript does not have to addj=Next[j]; Num=0; }                                                                    //System.out.println (j);                    }            }                                            }Else{System.out.println ("The pattern string must be greater than or equal to the main string!" "); }        returnlist; }            /*** 1, the method is used to return a next[] array, which holds the corresponding t{0~j-1} string of the pattern string (the longest prefix and the number of the same matching characters of the suffix) j is the subscript of the pattern String * 2, pattern is the mode string, to convert to char[] , if you want to search for freedom, it is necessary to convert the freedom to f,r,e,e,d,o,m char type array * * 3, this method is implemented with the idea of recursion, you can write the next array at a glance.     In the back will explain! *       */     Public int[] Getnextarray (String pattern) {intNext[] =New int[P.length]; next[0] = 1; intj = 0;//Next array subscript        intK =-1;//used to temporarily save the value of the next array//because the next array is designed to seek DMP, the entire next array is shifted to the right by 1, so the first bit is generally-1, which means there is no such string//and Next[1]=0, because the second position of the string to be t{0~j-1} prefix and suffix of the longest length of the same value, so 1 characters is an empty set, this will be implemented in the method body//when J assigned the last word, it jumps out of the loop, and if the string has 8 characters, then J must be less than 8-1         while(j<p.length-1) {            if(k==-1| | p[k]==P[j]) {                //If the match succeeds, the J,k two subscript is added to compare the next combination for equalityJ + +; K++; NEXT[J]=K; } Else {                //if it doesn't match, then J still doesn't move, K takes the value of the previous Kk = Next[k];//know K is 1 no match value returned 0            }        }        returnNext; }     Public Static voidMain (String args[]) {DMPtest1 dmp=NewDMPtest1 ("abc", "Afwefwaefaaaaabcawiefjawoijfeioawjofabc");//initialized for next array//Dmp.displaynext ();List = Dmp.gettargetindex ();//iterates through the matching main string and returns the index to the list         for(intI=0;i<list.size (); i++) {System.out.println ("The position of the string in the main string is" +List.get (i)); } System.out.println ("Total {" +list.size () + "} Matching Results"); }}

KMP Algorithm for Java implementation