聶永的博客

/**
 * JAVA兩種排序復(fù)習(xí)
 * 針對(duì)具體對(duì)象編寫相應(yīng)的排序代碼，這一部分是經(jīng)常變動(dòng)的部分
 * 排序Arrays.sort方法為不變的部分，封裝了具體排序算法
 * 兩者結(jié)合，一個(gè)策略模式出來(lái)了
 * 
 * @author xiaomin
 */
public class Person implements Serializable, Comparable<Person> {
 private static final long serialVersionUID = -23536L;
 
 private String name;
 private int age;

 public Person() {
 }

 public Person(String name, int age) {
  this.name = name;
  this.age = age;
 }

 public String getName() {
  return name;
 }

 public void setName(String name) {
  this.name = name;
 }

 public int getAge() {
  return age;
 }

 public void setAge(int age) {
  this.age = age;
 }
 
 // 正序排列,針對(duì)具體bean的排序,經(jīng)常變動(dòng)的部分
 public int compareTo(Person o) {
  if (o == null)
   return -1;

  return this.getAge() < o.getAge() ? -1 : (this.getAge() == o.getAge() ? 0 : 1);
 }

 public String toString() {
  return "name : " + getName() + " age : " + getAge();
 }

 public static void main(String... args) {
  Person[] persons = { new Person("a", 12), new Person("b", 10),
    new Person("demo", 23), new Person("hello", 22),
    new Person("hello", 32) };

  System.out.println("排序前 ......");
  System.out.println(Arrays.toString(persons));

  System.out.println("排序后 ......");
  Arrays.sort(persons);
  System.out.println(Arrays.toString(persons));

  System.out.println("使用自定義排序 ......");
  
  // 適用于沒(méi)有繼承Comparable的bean或需要自行定制的排序方式
  Arrays.sort(persons, new Comparator<Person>() {
   public int compare(Person o1, Person o2) {// 倒敘排列    
    return o1.getAge() > o2.getAge() ? -1 : (o1.getAge() == o2.getAge() ? 0 : 1);
   }
  });

  System.out.println(Arrays.toString(persons));
 }
}

/**
 * 自定義冒泡排序算法，演示使用，用以替代系統(tǒng)默認(rèn)的Arrays.sort
 * @author xiaomin
 *
 */
public class BubbleSort { 
 public static void main(String[] args) {
  Person[] persons = { new Person("a", 12), new Person("b", 10),
    new Person("demo", 23), new Person("hello", 22),
    new Person("hello", 32) };

  System.out.println("排序前 ......");
  System.out.println(Arrays.toString(persons));

  System.out.println("排序后 ......");
  bubble(persons);
  System.out.println(Arrays.toString(persons));

  System.out.println("使用自定義排序 ......");
  
  // 適用于沒(méi)有繼承Comparable的bean或需要自行定制的排序方式
  bubble(persons, new Comparator<Person>() {
   public int compare(Person o1, Person o2) {// 倒敘排列    
    return o1.getAge() > o2.getAge() ? -1 : (o1.getAge() == o2.getAge() ? 0 : 1);
   }
  });

  System.out.println(Arrays.toString(persons));
 }
 
 public static <T> void bubble(T [] ts, Comparator<? super T> c){  
  for(int i = 0; i < ts.length; i ++){
   for(int j = ts.length -1; j > i; j--){
    if(c.compare(ts[j-1], ts[j]) > 0){
     swap(ts, j-1, j);
    }
   }
  }
 }
 
 public static <T extends Comparable<T>> void bubble(T [] ts){  
  for(int i = 0; i < ts.length; i ++){
   for(int j = ts.length -1; j > i; j--){
    if(ts[j-1].compareTo(ts[j]) > 0){
     swap(ts, j-1, j);
    }
   }
  }
 }
 
 private static <T> void swap(T [] ints,int index1, int index2){
  T temp = ints[index1];
  
  ints[index1] = ints[index2];
  
  ints[index2] = temp;
 }
}

兩種排序輸出結(jié)果：

排序前 ......
[name : a age : 12, name : b age : 10, name : demo age : 23, name : hello age : 22, name : hello age : 32]
排序后 ......
[name : b age : 10, name : a age : 12, name : hello age : 22, name : demo age : 23, name : hello age : 32]
使用自定義排序 ......
[name : hello age : 32, name : demo age : 23, name : hello age : 22, name : a age : 12, name : b age : 10]
若有時(shí)間，也可以實(shí)現(xiàn)其它常見(jiàn)的排序算法。