Java数据结构---基于数组的表

引章小姐

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; [1] [2] [3] 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<length;i ){ list=otherList.list.getCopy(); } } //methods public boolean isEmpty(){ return (length==0); } public boolean isFull(){ return (length==maxSize); } public int listSize(){ return length; } public int maxListSize(){ return maxSize; } public void print(){ for(int i=0;i<length;i ){ System.out.print(list " "); } System.out.println(); } public boolean isItemAtEqual(int location,DataElement item){ return(list[location].equals(item)); } public void insrtAt(int location,DataElement insertItem){ if(location<0||location> 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=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<0||location>=length){ System.err.println("The location you want to remove is out of range!!"); } else{ for(int i=location;i<length-1;i ){ list=list[i 1]; } list[length]=null; length--; } } public DataElement retrieveAt(int location){ if(location<0||location>=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<0||location>=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;i<length;i ){ list=null; } length=0; System.gc(); } 上一页 [1] [2] [3] public void copyList(ArrayListClass otherList){ if(this!=otherList){ for(int i=0;i<length;i ) list=null; System.gc(); maxSize=otherList.maxSize; length=otherList.length; list=new DataElement[maxSize]; for(int j=0;j<length;j ) list[j]=otherList.list[j].getCopy(); } } public abstract int seqSearch(DataElement seqItem); public abstract void insert(DataElement insertItem); public abstract void remove(DataElement removeItem); } 看到代码的最后你回发现这个类其实是一个抽象类,为什么要这样定义呢?之所以这样我们是为了针对不同是类型:顺序表和非顺序表.不难想象他们的一些方法是存在差异的,先看一下非顺序表: public class UnorderedArrayList extends ArrayListClass{ /** * */ public UnorderedArrayList() { super(); // TODO Auto-generated constructor stub } /* (non-Javadoc) * @see ArrayListClass#seqSearch(DataElement) */ public int seqSearch(DataElement seqItem) { // TODO Auto-generated method stub int loc; boolean found=false; for(loc=0;loc<length;loc ) if(list[loc].equals(seqItem)) { found=true; break; } if(found) return loc; else return -1; } /* (non-Javadoc) * @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. 上一页 [1] [2] [3]