在当前项目下新建一个Floder文件
然后将下载的驱动导入此文件,前四种方法仅供了解,重点第五种方法,需要创建一个配置文件
@Test
public void test1() {
ArrayList coll = new ArrayList();
coll.add(new Person("jerry",20));
coll.add(123);
coll.add(456);
coll.add(new String ("tom"));
coll.add(false);
//contains(Object obj):判断当前集合中是否包含obj
//我们在判断时会调用obj对象所在类的equals()方法
boolean contains = coll.contains(123);
System.out.println(contains);
System.out.println(coll.contains(new String("tom")));
System.out.println(coll.contains(new Person("jerry", 20)));
//2.ContainsSAll(Collection coll1):判断形参对应的coll1是否都存在于当前集合中
Collection coll1 = Arrays.asList(123,4567);
System.out.println(coll.containsAll(coll1));
// coll.forEach(System.out::println);
}
@Test
public void test2(){
// 3.remove(Object obj)
Collection coll = new ArrayList();
coll.add(new Person("jerry",20));
coll.add(123);
coll.add(456);
coll.add(new String ("tom"));
coll.add(false);
boolean remove = coll.remove(1234);
coll.remove(new Person("jerry",20));
System.out.println(coll);
System.out.println("************");
// System.out.println(remove);
//removeAll(Collection coll1):从当前集合中移除coll1中所有的元素
Collection coll1 = Arrays.asList(123,456);
coll.removeAll(coll1);
System.out.println(coll);
}
@Test
public void test3(){
Collection coll = new ArrayList();
coll.add(new Person("jerry",20));
coll.add(123);
coll.add(456);
coll.add(new String ("tom"));
coll.add(false);
//5. retainAll(Collection coll1)交集:获取当前集合和coll集合的交集,并返回给当前集合。
// Collection coll1 = Arrays.asList(123,456,789);
// coll.retainAll(coll1);
// System.out.println(coll);
//6.equals(Object obj):要想返回true,需要判断当前集合和形参集合得元素是否相同
Collection coll1 = new ArrayList();
coll1.add(new Person("jerry",20));
coll1.add(456);
coll1.add(123);
coll1.add(new String ("tom"));
coll1.add(false);
System.out.println(coll.equals(coll1));
}
@Test
public void test4(){
Collection coll = new ArrayList();
coll.add(new Person("jerry",20));
coll.add(123);
coll.add(456);
coll.add(new String ("tom"));
coll.add(false);
//7. hasCode():返回当前对象的哈希值
System.out.println(coll.hashCode());
//8.集合----》数组
Object[] arr = coll.toArray();
for (int i = 0; i < arr.length; i++) {
System.out.println(arr[i]);
}
//拓展:数组转换为集合:调用Arrays类得静态方法aslist()
List<String> list = Arrays.asList(new String[]{"AA", "BB", "CC"});
System.out.println(list);
// List<int[]> arr1 = Arrays.asList(new int[]{123, 456});
List arr1 = Arrays.asList(123.456);
System.out.println(arr1.size());
List arr2 = Arrays.asList(new Integer[]{123,456});
System.out.println(arr2.size());
//9.iterator():返回iterator接口的实例,用于遍历集合元素,放在IteratorTest.java中
}