package cn.itcast.p2.toolclass.collections.demo;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.TreeSet;
import cn.itcast.p2.comparator.ComparatorByLength;
public class CollectionsDemo {
public static void main(String[] args) {
/*
* Collections：是集合框架的工具类。
* 里面的方法都是静态的。
*/
demo_4()
}
public static void demo_4() {
List<String> list = new ArrayList<String>();
list.add("abcde");
list.add("cba");
list.add("zhangsan");
list.add("zhaoliu");
list.add("xiaoqiang");
System.out.println(list);
// Collections.replaceAll(list, "cba", "nba"); // set(indexOf("cba"),"nba");
Collections.shuffle(list);
// Collections.fill(list, "cc");
System.out.println(list);
}
public static void demo_3() {
/*
TreeSet<String> ts = new TreeSet<String>(new Comparator<String>(){
@Override
public int compare(String o1, String o2) {
int temp = o2.compareTo(o1);
return temp;
}
});
*/
TreeSet<String> ts = new TreeSet<String>(Collections.reverseOrder(new
ComparatorByLength()));
ts.add("abc");
ts.add("hahaha");
ts.add("zzz");
ts.add("aa");
ts.add("cba");
System.out.println(ts);
}
public static void demo_2(){
List<String> list = new ArrayList<String>();
list.add("abcde");
list.add("cba");
list.add("aa");
list.add("zzz");
list.add("cba");
list.add("nbaa");
// Collections.sort(list);
System.out.println(list);
// int index = Collections.binarySearch(list, "cba");
// System.out.println("index="+index);
//获取最大值。
String max = Collections.max(list,new ComparatorByLength());
System.out.println("max="+max);
}
public static void demo_1(){
List<String> list = new ArrayList<String>();
list.add("abcde");
list.add("cba");
list.add("aa");
list.add("zzz");
list.add("cba");
list.add("nbaa");
System.out.println(list);
//对list集合进行指定顺序的排序。
// Collections.sort(list);
// mySort(list);
// mySort(list,new ComparatorByLength());
Collections.sort(list,new ComparatorByLength());
System.out.println(list);
}
public static <T> void mySort(List<T> list,Comparator<? super T> comp){
for (int i = 0; i < list.size()-1; i++) {
for (int j = i+1; j < list.size(); j++) {
if(comp.compare(list.get(i), list.get(j))>0){
// T temp = list.get(i);
// list.set(i, list.get(j));
// list.set(j, temp);
Collections.swap(list, i, j);
}
}
}
}
public static <T extends Comparable<? super T>> void mySort(List<T> list){
for (int i = 0; i < list.size()-1; i++) {
for (int j = i+1; j < list.size(); j++) {
if(list.get(i).compareTo(list.get(j))>0){
// T temp = list.get(i);
// list.set(i, list.get(j));
// list.set(j, temp);
Collections.swap(list, i, j);
}
}
}
}
}