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java数据结构——基于数组的表
我没看过 其他语言版的数据结构,但觉得java的实现方法很巧妙--用类和对象来实现.基于数组的表,思想很简单就是定义一个类用来存储一组数据,我定义的是arraylistclass类,在类中定义用来操作数组的方法.其实就是 这么简单,但具体操作起来就会遇到很多麻烦了!我们这个arraylistclass类中首先应该包括一个数组型的域list,用来存放数据,这样放在同一数组中数据之间就产生了位置上的联系,使对数据的操作便的简单.然而这个数组到底是什么数据类型的,我们期望这个表能用于所有的数据类型,我们不能将他单纯的固定成某一种.所以我们必须将这个数据普通化,解决的办法就是定义一个类,作为所有数据类型的超类.看这个dataelement: public abstract class dataelement { public abstract boolean equals(dataelement otherelement); public abstract int compareto(dataelement otherelement); public abstract void makecopy(dataelement otherelement); public abstract dataelement getcopy();}将他定义成为抽象的,再在定义其他数据类型时继承并实现它,我定义了两个数据类型intelement和stringelement:intelement:public class intelement extends dataelement { protected int num; //constructors public intelement(){ num=0; } public intelement(int number){ num=number; } public intelement(intelement otherelement){ num=otherelement.num; } ///get-set methods public void setnum(int number){ num=number; } public int getnum(){ return num; } /* (non-javadoc) * @see dataelement#equals(dataelement) */ public boolean equals(dataelement otherelement) { // todo auto-generated method stub intelement newe=(intelement)otherelement; return (this.num==newe.num); } /* (non-javadoc) * @see dataelement#compareto(dataelement) */ public int compareto(dataelement otherelement) { // todo auto-generated method stub intelement newe=(intelement)otherelement; if(this.num==newe.num) return 0; else if(this.num>newe.num) return 1; else return -1; } /* (non-javadoc) * @see dataelement#makecopy(dataelement) */ public void makecopy(dataelement otherelement) { // todo auto-generated method stub intelement newe=(intelement)otherelement; this.num=newe.num; } /* (non-javadoc) * @see dataelement#getcopy() */ public dataelement getcopy() { // todo auto-generated method stub intelement newelement=new intelement(); newelement.num=this.num; return newelement; } public string tostring(){ return string.valueof(num); }}stringelement:public class stringelement extends dataelement { /** * */ private string str; //constructors public stringelement() { str=null; } public stringelement(string string){ str=string; } public stringelement(stringelement otherelement){ str=otherelement.str; } //get-set methods public void setstr(string string){ str=string; } public string getstr(){ return str; } /* (non-javadoc) * @see dataelement#equals(dataelement) */ public boolean equals(dataelement otherelement) { // todo auto-generated method stub stringelement newe=(stringelement)otherelement; return (str==newe.str); } /* (non-javadoc) * @see dataelement#compareto(dataelement) */ public int compareto(dataelement otherelement) { // todo auto-generated method stub stringelement newe=(stringelement)otherelement; return (str.compareto(newe.str)); } /* (non-javadoc) * @see dataelement#makecopy(dataelement) */ public void makecopy(dataelement otherelement) { // todo auto-generated method stub stringelement newe=(stringelement)otherelement; str=newe.str; } /* (non-javadoc) * @see dataelement#getcopy() */ public dataelement getcopy() { // todo auto-generated method stub stringelement othere=new stringelement(); othere.str=str; return othere; } public string tostring(){ return str; }}已经定义好了数据类型,所以list的数据类型我们就可以定义为dateelement[]了,这样就可以包括所以你想要的了,只要你在用的时候定义一个dataelement的子类就行了,这正是java继承的精髓所在.我们接着定义arraylistclass类: protected int length; protected int maxsize; protected dataelement[] list;这就是它的所有域了.接下来就是它的方法了,我们对表的操作应该有很多种,比如插入、查询、删减等等,我们要逐个的实现,具体方法不再赘述,且看最后完成代码public abstract class arraylistclass { //fields protected int length; protected int maxsize; protected dataelement[] list; //defalt constructors public arraylistclass(){ length=0; maxsize=100; list=new dataelement[maxsize]; } //constructors public arraylistclass(int size){ if(size<=0){ system.err.println("the arry size must be positive.creating an array of size 100."); maxsize=100; } else maxsize=size; length=0; list=new dataelement[maxsize]; } public arraylistclass(arraylistclass otherlist){ maxsize=otherlist.maxsize; length=otherlist.length; list=new dataelement[maxsize]; for(int i=0;i+maxsize){ system.out.println("the position of the item to be inserted is out of range!!"); } else if(length>=maxsize) system.err.println("can't insert in a full list!!"); else{ for(int i=length;i>location;i--){ list[i]=list[i-1]; } list[location]=insertitem.getcopy(); length++; } } public void insertend(dataelement insertitem){ if(length>=maxsize){ system.err.println("can't insert in a full list!!"); } else{ list[length]=insertitem.getcopy(); length++; } } public void removeat(int location){ if(location<0location>=length){ system.err.println("the location you want to remove is out of range!!"); } else{ for(int i=location;i=length){ system.err.println("the location of item to be retrieved is out of range!!"); return null; } else{ return list[location].getcopy(); } } public void replacat(int location,dataelement repitem){ if(location<0location>=length) system.out.println("the position of item to be replaced is out of range!!"); else list[location]=repitem.getcopy(); } public void clearlist(){ for(int i=0;ijavadoc) * @see arraylistclass#seqsearch(dataelement) */ public int seqsearch(dataelement seqitem) { // todo auto-generated method stub int loc; boolean found=false; for(loc=0;locjavadoc) * @see arraylistclass#insert(dataelement) */ public void insert(dataelement insertitem) { // todo auto-generated method stub int loc; if(length==0) list[length++]=insertitem.getcopy(); else if(length==maxsize) system.err.println("can't insert in a full list!!"); else{ loc=seqsearch(insertitem); if(loc==-1) list[length++]=insertitem.getcopy(); else system.err.println("the item to be inserted is allready in the list!!"); } } /* (non-javadoc) * @see arraylistclass#remove(dataelement) */ public void remove(dataelement removeitem) { // todo auto-generated method stub int loc; if(length==0) system.err.println("can't delete from a empty list!!"); else{ loc=seqsearch(removeitem); if(loc!=-1) removeat(loc); else system.err.println("the item to be deleted is not in the list!!"); } }}就是这么简单!!相信顺序表也可以轻松高顶了.
