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Collections工具类

1 操作Collection及Map工具类

package lianxi2;import java.util.ArrayList;import java.util.Arrays;import java.util.Collections;import java.util.List;import org.junit.Test;public class TestCollections {@Test   public void test1(){    List list = new ArrayList();    list.add(3242);    list.add(23);    list.add(55);    list.add(2233);    list.add(90);    System.out.println(list);    System.out.println(Collections.max(list));    Collections.reverse(list);    System.out.println(list);    Collections.swap(list, 3, 4);    System.out.println(list);    //copy()方法    List list1 = Arrays.asList(new Object[list.size()]);    Collections.copy(list1, list);    System.out.println("list1="+list);    //保证线程安全    List list2 = Collections.synchronizedList(list);    System.out.println("list2="+list2);}}

结果:

[3242, 23, 55, 2233, 90]
3242
[90, 2233, 55, 23, 3242]
[90, 2233, 55, 3242, 23]
list1=[90, 2233, 55, 3242, 23]
list2=[90, 2233, 55, 3242, 23]

Collections工具类