Collection_Compare
冒泡
package com.bjsxt.sort.bubble; import java.util.Arrays; public class BubbleSort1 { /** * @param args */ public static void main(String[] args) { int[] arr ={9,8,7,6,5}; sort(arr); } //第一版本，很简单 public static void sort(int[] arr){ int len =arr.length; for(int j=0;j<len-1;j++){ System.out.println("第"+(j+1)+"趟"); for(int i=0;i<len-1;i++){ System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } } } public static void sortSecond(int[] arr){ System.out.println("第一趟"); for(int i=0;i<arr.length-1;i++){ System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } System.out.println("第二趟"); for(int i=0;i<arr.length-1;i++){ System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } System.out.println("第三趟"); for(int i=0;i<arr.length-1;i++){ System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } System.out.println("第四趟"); for(int i=0;i<arr.length-1;i++){ System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } } public static void sortFirst(int[] arr){ System.out.println("第一趟"); for(int i=0;i<arr.length-1;i++){ System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } /* //第一趟 第一次 System.out.println("第一趟 第一次"); int i=0; if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); System.out.println("第一趟 第二次"); i++; if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); System.out.println("第一趟 第三次"); i++; if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); System.out.println("第一趟 第四次"); i++; if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); */ } }
package com.bjsxt.sort.bubble; import java.util.Arrays; public class BubbleSort2 { /** * @param args */ public static void main(String[] args) { int[] arr ={9,8,7,6,5}; sort(arr); } //第二版本，减少每一趟的次数 public static void sort(int[] arr){ int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 System.out.println("第"+(j+1)+"趟"); for(int i=0;i<len-1-j;i++){ //次数 System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } } } }
package com.bjsxt.sort.bubble; import java.util.Arrays; /** * 最终版本：考虑存在顺序 * @author Administrator * */ public class BubbleSort { /** * @param args */ public static void main(String[] args) { int[] arr ={1,2,9,3,4}; sort1(arr); System.out.println("==========final============"); arr =new int[]{9,1,2,3,4}; sortFinal(arr); } //第二版本，减少每一趟的次数 public static void sortFinal(int[] arr){ boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } System.out.println(Arrays.toString(arr)); } if(sorted){ //减少趟数 break; } } } //第二版本，减少每一趟的次数 public static void sort1(int[] arr){ int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 System.out.println("第"+(j+1)+"趟"); for(int i=0;i<len-1-j;i++){ //次数 System.out.print("第"+(i+1)+"次"); if(arr[i]>arr[i+1]){ int temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; } System.out.println(Arrays.toString(arr)); } } } }
引用数据类型：
1.整数小数Integer Float Double直接比较基本数据类型的大小
2.比较unicode码之差
3.字符串：
package com.bjsxt.sort.innerType; /** * 内置引用数据类型(常用)的比较 * @author Administrator * */ public class Demo01 { /** * @param args */ public static void main(String[] args) { Integer a ; //根据基本数据类型大小 Character ch; //根据Unicode编码顺序 String str="abc"; //如果其中一个是例外一个起始开始的子串，返回长度之差 String str2 ="abcd123"; //否则返回第一个不相等的unicode码之差 System.out.println(str.compareTo(str2)); str ="abc"; str2 ="aad"; System.out.println(str.compareTo(str2)); java.util.Date d ; //根据日期的长整形数比较 } }
字符串的冒泡：
/** * @param args */ public static void main(String[] args) { String[] arr ={"a","abcd","abc","def"}; //从到小排序 降序 boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(((Comparable)arr[i]).compareTo(arr[i+1])<0){ String temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } } if(sorted){ //减少趟数 break; } } System.out.println(Arrays.toString(arr)); }
时间的冒泡：
/** * @param args */ public static void main(String[] args) { Date[] arr =new Date[3]; arr[0] =new Date(); arr[1] =new Date(System.currentTimeMillis()-1000*60*60); arr[2] =new Date(System.currentTimeMillis()+1000*60*60); //降序 //从大到小排序 降序 boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(((Comparable)arr[i]).compareTo(arr[i+1])<0){ Date temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } } if(sorted){ //减少趟数 break; } } System.out.println(Arrays.toString(arr)); }
封装+泛型之后：
package com.bjsxt.sort.innerType; import java.util.Comparator; import java.util.List; /** * 排序 * @author Administrator * */ public class Utils { /** * List的排序+比较器 * @param list * @param com */ public static <T> void sort(List<T> list,Comparator<T> com){ //第一步:转成数组 Object[] arr =list.toArray(); sort(arr,com); //第二步:改变容器中对应的值 for(int i=0;i<arr.length;i++){ list.set(i, (T)(arr[i])); } } /** * 数组的排序 （降序）+Comparator接口 * @param arr */ public static <T> void sort(Object[] arr,Comparator<T> com){ //从大到小排序 降序 boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(com.compare((T)arr[i], (T)arr[i+1])<0){ Object temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } } if(sorted){ //减少趟数 break; } } } /** * 容器排序 (使用泛型方法) */ public static <T extends Comparable<T>> void sort(List<T> list){ //第一步:转成数组 Object[] arr =list.toArray(); sort(arr); //第二步:改变容器中对应的值 for(int i=0;i<arr.length;i++){ list.set(i, (T)(arr[i])); } } /** * 数组排序 (使用泛型方法) */ public static <T extends Comparable<T>> void sort(T[] arr){ //从大到小排序 降序 boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(((Comparable)arr[i]).compareTo(arr[i+1])<0){ T temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } } if(sorted){ //减少趟数 break; } } } /** * 数组的排序 （降序） * @param arr */ public static void sort(Object[] arr){ //从大到小排序 降序 boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(((Comparable)arr[i]).compareTo(arr[i+1])<0){ Object temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } } if(sorted){ //减少趟数 break; } } } }
实例：
package com.bjsxt.sort.innerType; import java.util.ArrayList; import java.util.Arrays; import java.util.Date; import java.util.List; public class Demo04 { /** * @param args */ public static void main(String[] args) { Date[] arr =new Date[3]; arr[0] =new Date(); arr[1] =new Date(System.currentTimeMillis()-1000*60*60); arr[2] =new Date(System.currentTimeMillis()+1000*60*60); Utils.sort(arr); //降序 System.out.println(Arrays.toString(arr)); //字符串 String[] arr2 ={"a","abcd","abc","def"}; Utils.sort(arr2); System.out.println(Arrays.toString(arr2)); System.out.println("==========List排序==========="); //存放容器中 List<String> list =new ArrayList<String>(); list.add("a"); list.add("abcd"); list.add("abc"); list.add("def"); Utils.sort(list); System.out.println(list); System.out.println("==========使用Comparator 排序数组==============="); arr2 =new String[]{"a","abcd","abc","def"}; Utils.sort(arr2,new StringComp()); System.out.println(Arrays.toString(arr2)); System.out.println("==========List排序+比较器==========="); list =new ArrayList<String>(); list.add("a"); list.add("abcd"); list.add("abc"); list.add("def"); Utils.sort(list,new StringComp()); System.out.println(list); } }
方法而：实现java.util.Comparator接口
package com.bjsxt.sort.innerType; /** * 排序规则的业务类 * @author Administrator * */ public class StringComp implements java.util.Comparator<String>{ /** * 按长度比较大小 * 正数 > * 负数 < * 0 == */ @Override public int compare(String o1, String o2) { int len1 =o1.length(); int len2 =o2.length(); return -(len1-len2); } }
package com.bjsxt.sort.innerType; import java.util.ArrayList; import java.util.Collections; import java.util.List; /** * 使用Collections对容器的比较 * 1、 public static <T> void sort(List<T> list, Comparator<? super T> c) * 2、public static <T extends Comparable<? super T>> void sort(List<T> list) * void sort(List<T> list) * @author Administrator * */ public class Demo05 { /** * @param args */ public static void main(String[] args) { List<String> list =new ArrayList<String>(); list.add("a"); list.add("abcd"); list.add("abc"); list.add("def"); Collections.sort(list,new StringComp()); System.out.println(list); list =new ArrayList<String>(); list.add("a"); list.add("abcd"); list.add("abc"); list.add("def"); Collections.sort(list); System.out.println(list); } }
新闻条目的排序：
package com.bjsxt.sort.refType; import java.text.SimpleDateFormat; import java.util.Date; /** * 新闻条目实体类 * @author Administrator * */ public class NewsItem implements java.lang.Comparable<NewsItem>{ //标题 private String title; //点击量 private int hits; //时间 private Date pubTime; public NewsItem() { } public NewsItem(String title, int hits, Date pubTime) { super(); this.title = title; this.hits = hits; this.pubTime = pubTime; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public int getHits() { return hits; } public void setHits(int hits) { this.hits = hits; } public Date getPubTime() { return pubTime; } public void setPubTime(Date pubTime) { this.pubTime = pubTime; } //时间降序 +点击量升序+标题降序 @Override public int compareTo(NewsItem o) { int result =0; //比较 时间 result =-this.pubTime.compareTo(o.pubTime); //降序 if(0==result){ //时间相同 //点击量 result =this.hits-o.hits; //升序 if(0==result){ //点击量相同 //标题 result=-this.title.compareTo(o.title);//降序 } } return result; } @Override public String toString() { StringBuilder sb =new StringBuilder(); sb.append("标题:").append(this.title); sb.append(",时间:").append(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(this.pubTime)); sb.append(",点击量:").append(this.hits).append("\n"); return sb.toString(); } }
package com.bjsxt.sort.refType; import java.util.ArrayList; import java.util.Collections; import java.util.Date; import java.util.List; import com.bjsxt.sort.innerType.Utils; /** * 使用Collections * @author Administrator * */ public class NewsItemApp { /** * @param args */ public static void main(String[] args) { List<NewsItem> news=new ArrayList<NewsItem>(); news.add(new NewsItem("美国后怕了，逃跑了悲剧了",50,new Date(System.currentTimeMillis()-1000*60*60))); news.add(new NewsItem("中国登上钓鱼岛了，全国欢呼了",100,new Date())); news.add(new NewsItem("小日本终于听话了，泪流满面笑了",60,new Date(System.currentTimeMillis()-1000*60*60))); System.out.println("排序前:"+news); //排序 //Collections.sort(news); Utils.sort(news); System.out.println("排序后"+news); } }
商品的排序：
package com.bjsxt.sort.refType; /** * 实体类 * @author Administrator * */ public class Goods { //商品名称 private String name; //价格 private double price; //收藏量 private int fav; public Goods() { // TODO Auto-generated constructor stub } public Goods(String name, double price, int fav) { super(); this.name = name; this.price = price; this.fav = fav; } public String getName() { return name; } public void setName(String name) { this.name = name; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } public int getFav() { return fav; } public void setFav(int fav) { this.fav = fav; } @Override public String toString() { return "商品名:"+name+",收藏量"+this.fav+",价格:"+this.price+"\n"; } }
package com.bjsxt.sort.refType; /** * 按价格排序的业务类 （降序） * @author Administrator * */ public class GoodsPriceComp implements java.util.Comparator<Goods> { @Override public int compare(Goods o1, Goods o2) { return -(o1.getPrice()-o2.getPrice()>0?1:(o1.getPrice()==o2.getPrice()?0:-1)); } }
package com.bjsxt.sort.refType; /** * 按收藏量排序的业务类 （升序） * @author Administrator * */ public class GoodsFavComp implements java.util.Comparator<Goods> { @Override public int compare(Goods o1, Goods o2) { return o1.getFav()-o2.getFav(); } }
package com.bjsxt.sort.refType; import java.util.ArrayList; import java.util.Collections; import java.util.List; public class GoodsApp { /** * @param args */ public static void main(String[] args) { List<Goods> list =new ArrayList<Goods>(); list.add(new Goods("老马视频",100,2000)); list.add(new Goods("老高视频",50,2000)); list.add(new Goods("老裴视频",1000,1000)); System.out.println("排序前:"+list); // Collections.sort(list,new GoodsPriceComp()); Collections.sort(list,new GoodsFavComp()); System.out.println("排序后:"+list); } }
TreeSet：
注意：在添加数据是排序，数据更改不会影响原来的属性
package com.bjsxt.sort.col; import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Person { private final String name;//名称 private final int handsome;//帅气指数 public Person() { name =null; handsome =0; } public Person(String name, int handsome) { super(); this.name = name; this.handsome = handsome; } public String getName() { return name; } public int getHandsome() { return handsome; } @Override public String toString() { return "姓名:"+this.name+",帅气指数:"+this.handsome+"\n"; } }
package com.bjsxt.sort.col; import java.util.Set; import java.util.TreeMap; public class TreeMapDemo { /** * @param args */ public static void main(String[] args) { Person p1 =new Person("您",100); Person p2 =new Person("刘德华",1000); Person p3 =new Person("梁朝伟",1200); Person p4 =new Person("老裴",50); TreeMap<Person,String> map =new TreeMap<Person,String>(new java.util.Comparator<Person>(){ @Override public int compare(Person o1, Person o2) { return -(o1.getHandsome()-o2.getHandsome()); } } ); map.put(p1, "bjsxt"); map.put(p2, "bjsxt"); map.put(p3, "bjsxt"); map.put(p4, "bjsxt"); //查看键 Set<Person> persons =map.keySet(); System.out.println(persons); } }
package com.bjsxt.sort.col; public class Worker implements java.lang.Comparable<Worker> { //工种 private String type; //工资 private double salary; public Worker() { // TODO Auto-generated constructor stub } public Worker(String type, double salary) { super(); this.type = type; this.salary = salary; } public String getType() { return type; } public void setType(String type) { this.type = type; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } /** * 按工资升序 */ @Override public int compareTo(Worker o) { return this.salary>o.salary?1:( this.salary==o.salary?0:-1); } @Override public String toString() { return "工种:"+this.type+",工资:"+this.salary+"\n"; } }
package com.bjsxt.sort.col; import java.util.TreeSet; /** * 实体类实现Comparable 接口的应用 * @author Administrator * */ public class TreeSetDemo2 { /** * @param args */ public static void main(String[] args) { Worker w1 =new Worker("垃圾回收员",12000); Worker w2 =new Worker("农民工",8000); Worker w3 =new Worker("程序猿",5000); TreeSet<Worker> employees =new TreeSet<Worker>(); employees.add(w1); employees.add(w2); employees.add(w3); System.out.println(employees); } }
TreeMap：
package com.bjsxt.sort.col; import java.util.Set; import java.util.TreeMap; public class TreeMapDemo { /** * @param args */ public static void main(String[] args) { Person p1 =new Person("您",100); Person p2 =new Person("刘德华",1000); Person p3 =new Person("梁朝伟",1200); Person p4 =new Person("老裴",50); TreeMap<Person,String> map =new TreeMap<Person,String>(new java.util.Comparator<Person>(){ @Override public int compare(Person o1, Person o2) { return -(o1.getHandsome()-o2.getHandsome()); } } ); map.put(p1, "bjsxt"); map.put(p2, "bjsxt"); map.put(p3, "bjsxt"); map.put(p4, "bjsxt"); //查看键 Set<Person> persons =map.keySet(); System.out.println(persons); } }
package com.bjsxt.sort.col; import java.util.TreeMap; public class TreeMapDemo02 { /** * @param args */ public static void main(String[] args) { Worker w1 =new Worker("垃圾回收员",12000); Worker w2 =new Worker("农民工",8000); Worker w3 =new Worker("程序猿",5000); TreeMap<Worker,String > employees =new TreeMap<Worker,String >(); employees.put(w1,"bjsxt"); employees.put(w2,"bjsxt"); employees.put(w3,"bjsxt"); System.out.println(employees.keySet()); } }
Collections 的相关方法：
package com.bjsxt.sort.util; import java.util.ArrayList; import java.util.Collections; import java.util.List; /** *1、 binarySearch(List<? extends Comparable<? super T>> list, T key) 容器有序 *2、sort(List<T> list) sort(List<T> list, Comparator<? super T> c) *3、reverse(List<?> list) 4、shuffle(List<?> list) 洗牌 5、swap(List<?> list, int i, int j) * @author Administrator * */ public class CollectionsDemo01 { /** * @param args */ public static void main(String[] args) { List<Integer> cards =new ArrayList<Integer>(); //shuffle 洗牌 模拟斗地主 for(int i=0;i<54;i++){ cards.add(i); } //洗牌 Collections.shuffle(cards) ; //依次发牌 List<Integer> p1 =new ArrayList<Integer>(); List<Integer> p2 =new ArrayList<Integer>(); List<Integer> p3 =new ArrayList<Integer>(); List<Integer> last =new ArrayList<Integer>(); for(int i=0;i<51;i+=3){ p1.add(cards.get(i)); p2.add(cards.get(i+1)); p3.add(cards.get(i+2)); } //最后三张为底牌 last.add(cards.get(51)); last.add(cards.get(52)); last.add(cards.get(53)); System.out.println("第一个人:"+p1); System.out.println("第二个人:"+p2); System.out.println("第三个人:"+p3); System.out.println("底牌为:"+last); } //反转 public static void test1(){ List<Integer> list =new ArrayList<Integer>(); list.add(1); list.add(2); list.add(3); list.add(4); System.out.println(list); Collections.reverse(list); System.out.println("反转之后"+list); } }
