public void testSort() {
    System.out.println("原始顺序：" + list);
    Collections.reverse(list);
    System.out.println("reverse后顺序：" + list);
    Collections.shuffle(list);
    System.out.println("shuffle后顺序：" + list);
    Collections.swap(list, 1, 3);
    System.out.println("swap后顺序：" + list);
    Collections.sort(list);
    System.out.println("sort后顺序：" + list);
    Collections.rotate(list, 1);
    System.out.println("rotate后顺序：" + list);
  }

  public void testSearch() {
    System.out.println("给定的list：" + list);
    System.out.println("max：" + Collections.max(list));
    System.out.println("min：" + Collections.min(list));
    System.out.println("frequency：" + Collections.frequency(list, "a李四"));
    Collections.replaceAll(list, "a李四", "aa李四");
    System.out.println("replaceAll之后：" + list);
    
    // 如果binarySearch的对象没有排序的话，搜索结果是不确定的
    System.out.println("binarySearch在sort之前：" + Collections.binarySearch(list, "c赵五"));
    Collections.sort(list);
    // sort之后，结果出来了
    System.out.println("binarySearch在sort之后：" + Collections.binarySearch(list, "c赵五"));

    Collections.fill(list, "A");
    System.out.println("fill：" + list);
  } 

 Map m = Collections.synchronizedMap(new HashMap());
   ...
 Set s = m.keySet(); // Needn't be in synchronized block
   ...
 synchronized (m) { // Synchronizing on m, not s!
   Iterator i = s.iterator(); // Must be in synchronized block
   while (i.hasNext())
     foo(i.next());
 }

  public void testUnmodifiable() {
    System.out.println("给定的list：" + list);
    List<String> unmodList = Collections.unmodifiableList(list);
    unmodList.add("再加个试试！"); // 抛出：java.lang.UnsupportedOperationException
    // 这一行不会执行了
    System.out.println("新的unmodList：" + unmodList);
  }

public void testOther() {
    List<String> list1 = new ArrayList<String>();
    List<String> list2 = new ArrayList<String>();
    // addAll增加变长参数
    Collections.addAll(list1, "大家好", "你好","我也好");
    Collections.addAll(list2, "大家好", "a李四","我也好");
    // disjoint检查两个Collection是否的交集
    boolean b1 = Collections.disjoint(list, list1);
    boolean b2 = Collections.disjoint(list, list2);
    System.out.println(b1 + "\t" + b2);
    // 利用reverseOrder倒序
    Collections.sort(list1, Collections.reverseOrder());
    System.out.println(list1);
  }

package com.bjpowernode.test;
import java.util.*;
import org.junit.Before;
import org.junit.Test;
public class CollectionsTest {
  private List<String> list = new ArrayList<String>();
  @Before
  public void init() {
    // 准备测试数据
    list.add("b张三");
    list.add("d孙六");
    list.add("a李四");
    list.add("e钱七");
    list.add("c赵五");
  }
  @Test
  public void testUnmodifiable() {
    System.out.println("给定的list：" + list);
    List<String> unmodList = Collections.unmodifiableList(list);
    unmodList.add("再加个试试！"); // 抛出：java.lang.UnsupportedOperationException
    // 这一行不会执行了
    System.out.println("新的unmodList：" + unmodList);
  }
  @Test
  public void testSort() {
    System.out.println("原始顺序：" + list);
    Collections.reverse(list);
    System.out.println("reverse后顺序：" + list);
    Collections.shuffle(list);
    System.out.println("shuffle后顺序：" + list);
    Collections.swap(list, 1, 3);
    System.out.println("swap后顺序：" + list);
    Collections.sort(list);
    System.out.println("sort后顺序：" + list);
    Collections.rotate(list, 1);
    System.out.println("rotate后顺序：" + list);
  }
  @Test
  public void testSearch() {
    System.out.println("给定的list：" + list);
    System.out.println("max：" + Collections.max(list));
    System.out.println("min：" + Collections.min(list));
    System.out.println("frequency：" + Collections.frequency(list, "a李四"));
    Collections.replaceAll(list, "a李四", "aa李四");
    System.out.println("replaceAll之后：" + list);
    // 如果binarySearch的对象没有排序的话，搜索结果是不确定的
    System.out.println("binarySearch在sort之前：" + Collections.binarySearch(list, "c赵五"));
    Collections.sort(list);
    // sort之后，结果出来了
    System.out.println("binarySearch在sort之后：" + Collections.binarySearch(list, "c赵五"));
    Collections.fill(list, "A");
    System.out.println("fill：" + list);
  }
  @Test
  public void testOther() {
    List<String> list1 = new ArrayList<String>();
    List<String> list2 = new ArrayList<String>();
    // addAll增加变长参数
    Collections.addAll(list1, "大家好", "你好","我也好");
    Collections.addAll(list2, "大家好", "a李四","我也好");
    // disjoint检查两个Collection是否的交集
    boolean b1 = Collections.disjoint(list, list1);
    boolean b2 = Collections.disjoint(list, list2);
    System.out.println(b1 + "\t" + b2);
    // 利用reverseOrder倒序
    Collections.sort(list1, Collections.reverseOrder());
    System.out.println(list1);
  }
}