Java 工具类的封装（对象中是否包含元素）

public static boolean contains(Object obj, Object element) {
if (obj == null) {
return false;
}
if (obj instanceof String) {
if (element == null) {
return false;
}
return ((String) obj).contains(element.toString());
}
if (obj instanceof Collection) {
return ((Collection<?>) obj).contains(element);
}
if (obj instanceof Map) {
return ((Map<?, ?>) obj).values().contains(element);
}

if (obj instanceof Iterator) {
Iterator<?> iter = (Iterator<?>) obj;
while (iter.hasNext()) {
Object o = iter.next();
if (equals(o, element)) {
return true;
}
}
return false;
}
if (obj instanceof Enumeration) {
Enumeration<?> enumeration = (Enumeration<?>) obj;
while (enumeration.hasMoreElements()) {
Object o = enumeration.nextElement();
if (equals(o, element)) {
return true;
}
}
return false;
}
if (obj.getClass().isArray() == true) {
int len = Array.getLength(obj);
for (int i = 0; i < len; i++) {
Object o = Array.get(obj, i);
if (equals(o, element)) {
return true;
}
}
}
return false;
}

/**`这里写代码片`
* 比较两个对象是否相等。<br>
* 相同的条件有两个，满足其一即可：<br>
* 1. obj1 == null && obj2 == null; 2. obj1.equals(obj2)
*
* @param obj1 对象1
* @param obj2 对象2
* @return 是否相等
*/
public static boolean equals(Object obj1, Object obj2) {
return (obj1 != null) ? (obj1.equals(obj2)) : (obj2 == null);
}