Comparable接口与Comparator

Comparable接口
1.接口
package com.ygl.strategy;
 
public  interfaceComparable {
 public   int  compareTo(Object o);
}
 
2.Cat类实现Comparable接口，并重写compareTo方法
package com.ygl.strategy;
 
public  classCat implementsComparable{
private  intheight;
private  intweight;
public  intgetHeight() {
    return  height;
}
public  voidsetHeight(intheight) {
    this.height
}
public  intgetWeight() {
    return  weight;
}
public Cat(intheight, intweight) {
    super();
    this.height
    this.weight
}
public  voidsetWeight(intweight) {
    this.weight
}
@Override
public String toString() {
    return  "Cat [height="+ height+  ", weight=" + weight+  "]";
}
@Override
public  intcompareTo(Object o) {
    if(o instanceof Cat){
        Catc=(Cat)o;
        if(this.getHeight()>c.getHeight()){
            return 1;
        }
        else  if(this.getHeight()<c.getHeight()){
            return -1;
        }else
            return 0;
    }
    return -100;//抛异常
}
 
}
3.定义排序规则

package com.ygl.strategy;
 
public  classDataSorter {
 
 
    public  static void  sort(Object[] a) {
// TODO Auto-generated method stub
        for(int i=a.length;i>0;i--){//遍历几次1-n
            for(int j=0;j<i-1;j++){
                Comparableo1=(Comparable)a[j];
                Comparableo2=(Comparable)a[j+1];
                if(o1.compareTo(o2)==1){
                    swap(a,j,j+1);
                }
            }
        }
    }
 
    
    
    
    
    private  static void swap(Object[] a, int x ,int y) {
        Objecttemp=a[x];
        a[x]=a[y];
        a[y]=temp;
        
    }
 
 
 
 
 
    public  static void sort(int[] a) {
// TODO Auto-generated method stub
        for(int i=a.length;i>0;i--){//遍历几次1-n
            for(int j=0;j<i-1;j++){
                if(a[j]>a[j+1]){
                    swap(a,j,j+1);
                }
            }
        }
    }
    
 
    
//************************************************************  
    
    private  static void swap(int[] a, int x, int y) {
        int temp=a[x];
        a[x]=a[y];
        a[y]=temp;
    }
 
 
 
 
    public  static void p(int[] a) {
// TODO Auto-generated method stub
        for(int i=0;i<a.length;i++){
            System.out.print(a[i]+" ");
        }
        System.out.println();
    }
 
4.测试
 
package com.ygl.strategy;
 
public  classTest {
public  staticvoidmain(String[] args) {
    int a[]={8,9,2,5};
    Cat[]c={newCat(8,5),newCat(2,5)};
    DataSorter.sort(c);
    DataSorter.p(c);
}
}
 //=============================================================
Comparator接口（推荐使用）
1.类一定要实现Comparable接口（理由略）
package com.ygl.strategy;
import java.util.Comparator;
import java.lang.Comparable;;
public  classDog implementsComparable<Dog>{
private  intfood;
private Comparator<Dog> comparator= newDogHeighgtComparator() ;
 
public Dog(intfood) {
this.food=food;
}
 
public Comparator<Dog> getComparator() {
    return  comparator;
}
 
public  voidsetComparator(Comparator<Dog> comparator) {
    this.comparator
}
 
public  intgetFood() {
    return  food;
}
 
public  voidsetFood(intfood) {
    this.food
}
 
@Override
public String toString() {
    return  "Dog [food="+ food+  "]";
}
 
public  intcompareTo(Dog o) {
 returncomparator.compare(this, o);
    
}
}
 
2.自定义比较器
package com.ygl.strategy;
 
import java.util.Comparator;
 
public  classDogHeighgtComparator implements Comparator<Dog> {
 
@Override
    public  int compare( Dog d1, Dogd2) {
        
        if(d1.getFood()>d2.getFood()){
            return 1;
        }else  if(d1.getFood()<d2.getFood()){
            return -1;
            
        }
        
        return 0;
    }
 
}
 
3.使用jdk自带排序类 Arrays.sort(d);

package com.ygl.strategy;
import java.util.Arrays;
 
public  classTest {
public  staticvoidmain(String[] args) {
    int a[]={8,9,2,5};
    Dog[]d={newDog(25),newDog(5)};
    Arrays.sort(d);
    DataSorter.p(d);
}
}