Java 集合 之 Collections

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// 对商家的产品(产品名称,产品价格)信息按价格排序 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Test {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // 对商家的产品(产品名称,产品价格)信息按价格排序 
        List list=new ArrayList();
        list.add(new Product("华硕电脑", 4000));
        list.add(new Product("东芝电脑", 3500));
        list.add(new Product("联想电脑", 5000));
        for(int i=0;i<list.size();i++)
        {
            Product p=(Product)list.get(i);
            System.out.println(p.getName()+","+p.getPrice());
        }
        
        //Collections  Arrays.sort()
        Collections.sort(list,new DecendComparator());
        System.out.println("排序完以后的结果:");
        for(int i=0;i<list.size();i++)
        {
            Product p=(Product)list.get(i);
            System.out.println(p.getName()+","+p.getPrice());
        }
        
    }
}



//产品类
public class Product implements Comparable{
    private String name;
    private double price;

    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }

    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;
    }

    @Override
    public int compareTo(Object o) {
        Product p=(Product)o;
        if(this.price<p.getPrice())
        {
            return 1;
        }else if(this.price>p.getPrice())
        {
            return -1;
        }
        return 0;
    }
    
    
}




//升序
import java.util.Comparator;

public class AscendComparator implements Comparator{

    @Override
    public int compare(Object o1, Object o2) {
        Product p1=(Product)o1;
        Product p2=(Product)o2;
        if(p1.getPrice()<p2.getPrice())
        {
            return -1;
        }else if(p1.getPrice()>p2.getPrice())
        {
            return 1;
        }
        return 0;
    }
    
}



//降序
import java.util.Comparator;

public class DecendComparator implements Comparator{

    @Override
    public int compare(Object o1, Object o2) {
        Product p1=(Product)o1;
        Product p2=(Product)o2;
        if(p1.getPrice()<p2.getPrice())
        {
            return 1;
        }else if(p1.getPrice()>p2.getPrice())
        {
            return -1;
        }
        return 0;
    }
    
}

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