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利用compareTo对java基于类的List进行排序

原创 Linux操作系统 作者:myfriend2010 时间:2019-03-23 13:12:04 0 删除 编辑
利用compareTo对java基于类的List进行排序

大致逻辑如下:先让类继承接口Comparable,并按照业务逻辑重写compareTo方法,然后调用Collections.sort(List)来进行排序。

 

分2个类:CompaerClass和CopmpareClassTest,在CompaerClass中继承接口Comparable,重写compareTo方法(增加按照4个字段进行排序的逻辑),在CopmpareClassTest生成测试数据,并进行排序,并输出结果。

 

一:CompaerClass类

public class CompaerClass implements Comparable {

    private int a;

    private String b;

    private String c;

    private String d;

    private String e;

 

    public int getA() {

       return a;

    }

 

    public void setA(int a) {

       this.a = a;

    }

 

    public String getB() {

       return b;

    }

 

    public void setB(String b) {

       this.b = b;

    }

 

    public String getC() {

       return c;

    }

 

    public void setC(String c) {

       this.c = c;

    }

 

    public String getD() {

       return d;

    }

 

    public void setD(String d) {

       this.d = d;

    }

 

    public String getE() {

       return e;

    }

 

    public void setE(String e) {

       this.e = e;

    }

 

    public int compareTo(Object tt) {

       CompaerClass t = (CompaerClass) tt;

       if((t.getA()+t.getB()+t.getC()+t.getD()).compareTo(this.a+this.b+this.c+this.d)>0)

       return -1;

       else if((t.getA()+t.getB()+t.getC()+t.getD()).compareTo(this.a+this.b+this.c+this.d)==0)

       return 0;

       else return 1;

    }

 

    public int hashCode() {

       final int prime = 31;

       int result = 1;

       result = prime * result + a;

       result = prime * result + ((b == null) ? 0 : b.hashCode());

       result = prime * result + ((c == null) ? 0 : c.hashCode());

       result = prime * result + ((d == null) ? 0 : d.hashCode());

       result = prime * result + ((e == null) ? 0 : e.hashCode());

       return result;

    }

 

    public boolean equals(Object obj) {

       if (this == obj)

           return true;

       if (obj == null)

           return false;

       if (!(obj instanceof CompaerClass))

           return false;

       final CompaerClass ther = (CompaerClass) obj;

       if (a != other.a)

           return false;

       if (b == null) {

           if (other.b != null)

               return false;

       } else if (!b.equals(other.b))

           return false;

       if (c == null) {

           if (other.c != null)

              return false;

       } else if (!c.equals(other.c))

           return false;

       if (d == null) {

           if (other.d != null)

              return false;

       } else if (!d.equals(other.d))

           return false;

       if (e == null) {

           if (other.e != null)

              return false;

       } else if (!e.equals(other.e))

           return false;

       return true;

    }

 

}

 

二:CopmpareClassTest类

import java.util.ArrayList;

import java.util.Collections;

import java.util.Iterator;

import java.util.List;

 

public class CopmpareClassTest {

 

       /**

        * @param args

        */

       public static void main(String[] args) {

              // TODO Auto-generated method stub

              List t = new ArrayList();

 

              CompaerClass c = new CompaerClass();

              c.setA(1);

              c.setB("a");

              c.setC("h");

              c.setD("o");

              c.setE("u");

              t.add(c);

              c = new CompaerClass();

              c.setA(5);

              c.setB("d");

              c.setC("i");

              c.setD("q");

              c.setE("x");

              t.add(c);

              c = new CompaerClass();

              c.setA(4);

              c.setB("g");

              c.setC("l");

              c.setD("w");

              c.setE("u");

              t.add(c);

              c = new CompaerClass();

              c.setA(9);

              c.setB("b");

              c.setC("n");

              c.setD("u");

              c.setE("y");

              t.add(c);

              c = new CompaerClass();

              c.setA(5);

              c.setB("d");

              c.setC("i");

              c.setD("p");

              c.setE("x");

              t.add(c);

              printTest(t);

              System.out.println("sort up");

              Collections.sort(t);

              printTest(t);

       }

 

       private static void printTest(List q) {

              for (Iterator t = q.iterator(); t.hasNext();) {

                     CompaerClass com = (CompaerClass) t.next();

                     System.out.println(com.getA() + "|" + com.getB() + "|" + com.getC()

                                   + "|" + com.getD() + "|" + com.getE());

              }

       }

 

}

 

 

测试结果如下:

 

1|a|h|o|u

5|d|i|q|x

4|g|l|w|u

9|b|n|u|y

5|d|i|p|x

sort up

1|a|h|o|u

4|g|l|w|u

5|d|i|p|x

5|d|i|q|x

9|b|n|u|y

 

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