125

ComparatorImpl package collection.sort.comparator; import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class ComparatorImpl { public static void main(String[] args) { System.out.println("==========使用Comparator排序数组==============="); String[] arr2 ={"a","abcd","abc","def"}; arr2 =new String[]{"a","abcd","abc","def"}; CompareUtils.sort(arr2,new StringCompare()); System.out.println(Arrays.toString(arr2)); System.out.println("==========使用Comparator排序List==========="); //存放容器中 List<String> list =new ArrayList<String>(); list =new ArrayList<String>(); list.add("a"); list.add("abcd"); list.add("abc"); list.add("def"); CompareUtils.sort(list,new StringCompare()); System.out.println(list); } } CompareUtils package collection.sort.comparator; import java.util.Comparator; import java.util.List; public class CompareUtils { /** * 数组的排序 (降序+Comparator接口) * @param arr */ @SuppressWarnings("unchecked") public static <T> void sort(Object[] arr,Comparator<T> com){ //从大到小排序降序 boolean sorted= true; int len =arr.length; for(int j=0;j<len-1;j++){ //趟数 sorted =true; //假定有序 for(int i=0;i<len-1-j;i++){ //次数 if(com.compare((T)arr[i], (T)arr[i+1])<0){ Object temp = arr[i]; arr[i] =arr[i+1]; arr[i+1] =temp; sorted =false; //假定失败 } } if(sorted){ //减少趟数 break; } } } /** * List的排序(降序+Comparator接口) * @param list * @param com */ @SuppressWarnings("unchecked") public static <T> void sort(List<T> list,Comparator<T> com){ //第一步:转成数组 Object[] arr =list.toArray(); sort(arr,com); //第二步:改变容器中对应的值 for(int i=0;i<arr.length;i++){ list.set(i, (T)(arr[i])); } } } StringCompare package collection.sort.comparator; import java.util.Comparator; /** * String排序规则的业务类 * @author zhushen * */ public class StringCompare implements Comparator<String>{ /**按String的长度来比较大小 *1.正数:o1>o2 *2.负数:o1<o2 *3.0:o1=o2 */ @Override public int compare(String o1, String o2) { return o1.length()-o2.length(); } }