Compareble 接口与Comparator接口使用示例

秒速五厘米 2022-09-24 05:18 208阅读 0赞

直接上代码

package com.galaxy.fym.model;
    
    import java.util.Comparator;
    
    /** * Created by fengyiming on 2016/7/25. */
    public class FymComparator{ 
    
        public Integer key;
    
        public String value;
    
        public FymComparator(){
    
        }
    
        public FymComparator(Integer key,String value){
            this.key = key;
            this.value = value;
        }
    
        /** * 定义了一个比较的方法 */
        public int compare(FymComparator obj2){
            if(this.key == null){
                return -1;
            }else if(obj2.getKey() == null){
                return 1;
            }else{
                int compareKeyValue = this.key.compareTo(obj2.getKey());
                if(compareKeyValue == 0){
                    return this.value.compareTo(obj2.getValue());
                }
                return compareKeyValue;
            }
        }
    
        /** * 定义了一个比较器 */
        public static Comparator<FymComparator> comparable = new Comparator<FymComparator>() {
            public int compare(FymComparator o1,FymComparator o2) {
                return o1.compare(o2);
            }
        };
    
        public Integer getKey() {
            return key;
        }
    
        public void setKey(Integer key) {
            this.key = key;
        }
    
        public String getValue() {
            return value;
        }
    
        public void setValue(String value) {
            this.value = value;
        }
    }

package com.galaxy.fym.model;
    
    /** * Created by fengyiming on 2016/7/25. * 千万要继承Comparable<Object>,不然实现的时候无法把类当参数，参数类型为默认的Object */
    public class FymCompareble implements Comparable<FymCompareble>{
    
        public Integer key;
    
        public String value;
    
    
        public FymCompareble(){
    
        }
    
        public FymCompareble(Integer key,String value){
            this.key = key;
            this.value = value;
        }
    
    
        public Integer getKey() {
            return key;
        }
    
        public void setKey(Integer key) {
            this.key = key;
        }
    
        public String getValue() {
            return value;
        }
    
        public void setValue(String value) {
            this.value = value;
        }
    
        /** * 定义了一个比较的方法 */
        public int compare(FymCompareble obj2){
            if(this.key == null){
                return -1;
            }else if(obj2.getKey() == null){
                return 1;
            }else{
                int compareKeyValue = this.key.compareTo(obj2.getKey());
                if(compareKeyValue == 0){
                    return this.value.compareTo(obj2.getValue());
                }
                return compareKeyValue;
            }
        }
    
        /** * Collections.sort()会自动调用这个方法排序 * @param o * @return */
        public int compareTo(FymCompareble o) {
            return this.compare(o);
        }
    }

测试类：

package com.galaxy.fym.test;
    
    import com.galaxy.fym.model.FymComparator;
    import com.galaxy.fym.model.FymCompareble;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.List;
    import java.util.Random;
    
    /** * Created by fengyiming on 2016/7/25. */
    public class FymTest { 
    
        private final static Integer SIZE = 10;
    
        private List<FymCompareble> comparebleList = new ArrayList<FymCompareble>(SIZE);
    
        private List<FymComparator> comparatorList = new ArrayList<FymComparator>(SIZE);
    
        private Random random = new Random();
    
        @Before
        public void init() {
            for (int i = 0; i < SIZE; i++) {
                int randomIndex = random.nextInt(SIZE);
                FymCompareble fymCompareble = new FymCompareble(SIZE - randomIndex, "index" + i);
                FymComparator fymComparator = new FymComparator(randomIndex, "index" + i);
                comparebleList.add(fymCompareble);
                comparatorList.add(fymComparator);
            }
    
            for (FymCompareble dto : comparebleList) {
                System.out.println("comparebleList :" + dto.getKey() + "--" + dto.getValue());
            }
            System.out.println("---------------------------------------------------------");
            for (FymComparator dto : comparatorList) {
                System.out.println("comparatorList :" + dto.getKey() + "--" + dto.getValue());
            }
            System.out.println("--------------------------sort before-------------------------------");
        }
    
        @Test
        public void printSort() {
            Collections.sort(comparebleList);
            Collections.sort(comparatorList, FymComparator.comparable);
        }
    
        @After
        public void print() {
            System.out.println("--------------------------sort after-------------------------------");
            for (FymCompareble dto : comparebleList) {
                System.out.println("comparebleList :" + dto.getKey() + "--" + dto.getValue());
            }
            System.out.println("---------------------------------------------------------------------------");
            for (FymComparator dto : comparatorList) {
                System.out.println("comparatorList :" + dto.getKey() + "--" + dto.getValue());
            }
        }
    }

输出结果

comparebleList :6--index0
    comparebleList :5--index1
    comparebleList :6--index2
    comparebleList :2--index3
    comparebleList :9--index4
    comparebleList :9--index5
    comparebleList :2--index6
    comparebleList :8--index7
    comparebleList :1--index8
    comparebleList :9--index9
    ---------------------------------------------------------
    comparatorList :4--index0
    comparatorList :5--index1
    comparatorList :4--index2
    comparatorList :8--index3
    comparatorList :1--index4
    comparatorList :1--index5
    comparatorList :8--index6
    comparatorList :2--index7
    comparatorList :9--index8
    comparatorList :1--index9
    --------------------------sort before-------------------------------
    --------------------------sort after-------------------------------
    comparebleList :1--index8
    comparebleList :2--index3
    comparebleList :2--index6
    comparebleList :5--index1
    comparebleList :6--index0
    comparebleList :6--index2
    comparebleList :8--index7
    comparebleList :9--index4
    comparebleList :9--index5
    comparebleList :9--index9
    ---------------------------------------------------------------------------
    comparatorList :1--index4
    comparatorList :1--index5
    comparatorList :1--index9
    comparatorList :2--index7
    comparatorList :4--index0
    comparatorList :4--index2
    comparatorList :5--index1
    comparatorList :8--index3
    comparatorList :8--index6
    comparatorList :9--index8
    
    Process finished with exit code 0