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Activities
Activities
Quickview
- An activity provides a user interface for a single screen in your application
- Activities can move into the background and then be resumed with their state restored
In this document
Key classes
See also
An Activity
is an application component that provides a screen with which users can interact in order to do something, such as dial the phone, take a photo, send an email, or view a map. Each activity is given a window in which to draw its user interface. The window typically fills the screen, but may be smaller than the screen and float on top of other windows.
An application usually consists of multiple activities that are loosely bound to each other. Typically, one activity in an application is specified as the "main" activity, which is presented to the user when launching the application for the first time. Each activity can then start another activity in order to perform different actions. Each time a new activity starts, the previous activity is stopped, but the system preserves the activity in a stack (the "back stack"). When a new activity starts, it is pushed onto the back stack and takes user focus. The back stack abides to the basic "last in, first out" queue mechanism, so, when the user is done with the current activity and presses the BACK key, it is popped from the stack (and destroyed) and the previous activity resumes. (The back stack is discussed more in the Tasks and Back Stack document.)
When an activity is stopped because a new activity starts, it is notified of this change in state through the activity's lifecycle callback methods. There are several callback methods that an activity might receive, due to a change in its state—whether the system is creating it, stopping it, resuming it, or destroying it—and each callback provides you the opportunity to perform specific work that's appropriate to that state change. For instance, when stopped, your activity should release any large objects, such as network or database connections. When the activity resumes, you can reacquire the necessary resources and resume actions that were interrupted. These state transitions are all part of the activity lifecycle.
The rest of this document discusses the basics of how to build and use an activity, including a complete discussion of how the activity lifecycle works, so you can properly manage the transition between various activity states.
Creating an Activity
To create an activity, you must create a subclass of Activity
(or an existing subclass of it). In your subclass, you need to implement callback methods that the system calls when the activity transitions between various states of its lifecycle, such as when the activity is being created, stopped, resumed, or destroyed. The two most important callback methods are:
onCreate()
setContentView()
to define the layout for the activity's user interface.onPause()
There are several other lifecycle callback methods that you should use in order to provide a fluid user experience between activities and handle unexpected interuptions that cause your activity to be stopped and even destroyed. All of the lifecycle callback methods are discussed later, in the section about Managing the Activity Lifecycle.
Implementing a user interface
The user interface for an activity is provided by a hierarchy of views—objects derived from the View
class. Each view controls a particular rectangular space within the activity's window and can respond to user interaction. For example, a view might be a button that initiates an action when the user touches it.
Android provides a number of ready-made views that you can use to design and organize your layout. "Widgets" are views that provide a visual (and interactive) elements for the screen, such as a button, text field, checkbox, or just an image. "Layouts" are views derived from ViewGroup
that provide a unique layout model for its child views, such as a linear layout, a grid layout, or relative layout. You can also subclass the View
and ViewGroup
classes (or existing subclasses) to create your own widgets and layouts and apply them to your activity layout.
The most common way to define a layout using views is with an XML layout file saved in your application resources. This way, you can maintain the design of your user interface separately from the source code that defines the activity's behavior. You can set the layout as the UI for your activity with setContentView()
, passing the resource ID for the layout. However, you can also create new View
s in your activity code and build a view hierarchy by inserting new View
s into a ViewGroup
, then use that layout by passing the root ViewGroup
to setContentView()
.
For information about creating a user interface, see the User Interface documentation.
Declaring the activity in the manifest
You must declare your activity in the manifest file in order for it to be accessible to the system. To decalare your activity, open your manifest file and add an <activity>
element as a child of the <application>
element. For example:
<manifest ... >
<application ... >
<activity android:name=".ExampleActivity" />
...
</application ... >
...
</manifest >
There are several other attributes that you can include in this element, to define properties such as the label for the activity, an icon for the activity, or a theme to style the activity's UI. See the <activity>
element reference for more information about available attributes.
Using intent filters
An <activity>
element can also specify various intent filters—using the <intent-filter>
element—in order to declare how other application components may activate it.
When you create a new application using the Android SDK tools, the stub activity that's created for you automatically includes an intent filter that declares the activity responds to the "main" action and should be placed in the "launcher" category. The intent filter looks like this:
<activity android:name=".ExampleActivity" android:icon="@drawable/app_icon">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
The <action>
element specifies that this is the "main" entry point to the application. The <category>
element specifies that this activity should be listed in the system's application launcher (to allow users to launch this activity).
If you intend for your application to be self-contained and not allow other applications to activate its activities, then you don't need any other intent filters. Only one activity should have the "main" action and "launcher" category, as in the previous example. Activities that you don't want to make available to other applications should have no intent filters and you can start them yourself using explicit intents (as discussed in the following section).
However, if you want your activity to respond to implicit intents that are delivered from other applications (and your own), then you must define additional intent filters for your activity. For each type of intent to which you want to respond, you must include an <intent-filter>
that includes an <action>
element and, optionally, a <category>
element and/or a <data>
element. These elements specify the type of intent to which your activity can respond.
For more information about how your activities can respond to intents, see the Intents and Intent Filters document.
Starting an Activity
You can start another activity by calling startActivity()
, passing it an Intent
that describes the activity you want to start. The intent specifies either the exact activity you want to start or describes the type of action you want to perform (and the system selects the appropriate activity for you, which can even be from a different application). An intent can also carry small amounts of data to be used by the activity that is started.
When working within your own application, you'll often need to simply launch a known activity. You can do so by creating an intent that explicitly defines the activity you want to start, using the class name. For example, here's how one activity starts another activity named SignInActivity
:
Intent intent = new Intent(this, SignInActivity.class);
startActivity(intent);
However, your application might also want to perform some action, such as send an email, text message, or status update, using data from your activity. In this case, your application might not have its own activities to perform such actions, so you can instead leverage the activities provided by other applications on the device, which can perform the actions for you. This is where intents are really valuable—you can create an intent that describes an action you want to perform and the system launches the appropriate activity from another application. If there are multiple activities that can handle the intent, then the user can select which one to use. For example, if you want to allow the user to send an email message, you can create the following intent:
Intent intent = new Intent(Intent.ACTION_SEND);
intent.putExtra(Intent.EXTRA_EMAIL, recipientArray);
startActivity(intent);
The EXTRA_EMAIL
extra added to the intent is a string array of email addresses to which the email should be sent. When an email application responds to this intent, it reads the string array provided in the extra and places them in the "to" field of the email composition form. In this situation, the email application's activity starts and when the user is done, your activity resumes.
Starting an activity for a result
Sometimes, you might want to receive a result from the activity that you start. In that case, start the activity by calling startActivityForResult()
(instead of startActivity()
). To then receive the result from the subsequent activity, implement the onActivityResult()
callback method. When the subsequent activity is done, it returns a result in an Intent
to your onActivityResult()
method.
For example, perhaps you want the user to pick one of their contacts, so your activity can do something with the information in that contact. Here's how you can create such an intent and handle the result:
private void pickContact() {
// Create an intent to "pick" a contact, as defined by the content provider URI
Intent intent = new Intent(Intent.ACTION_PICK, Contacts.CONTENT_URI);
startActivityForResult(intent, PICK_CONTACT_REQUEST);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// If the request went well (OK) and the request was PICK_CONTACT_REQUEST
if (resultCode == Activity.RESULT_OK && requestCode == PICK_CONTACT_REQUEST) {
// Perform a query to the contact's content provider for the contact's name
Cursor cursor = getContentResolver().query(data.getData(),
new String[] {Contacts.DISPLAY_NAME}, null, null, null);
if (cursor.moveToFirst()) { // True if the cursor is not empty
int columnIndex = cursor.getColumnIndex(Contacts.DISPLAY_NAME);
String name = cursor.getString(columnIndex);
// Do something with the selected contact's name...
}
}
}
This example shows the basic logic you should use in your onActivityResult()
method in order to handle an activity result. The first condition checks whether the request was successful—if it was, then the resultCode
will be RESULT_OK
—and whether the request to which this result is responding is known—in this case, the requestCode
matches the second parameter sent with startActivityForResult()
. From there, the code handles the activity result by querying the data returned in an Intent
(the data
parameter).
What happens is, a ContentResolver
performs a query against a content provider, which returns a Cursor
that allows the queried data to be read. For more information, see the Content Providers document.
For more information about using intents, see the Intents and Intent Filters document.
Shutting Down an Activity
You can shut down an activity by calling its finish()
method. You can also shut down a separate activity that you previously started by calling finishActivity()
.
Note: In most cases, you should not explicitly finish an activity using these methods. As discussed in the following section about the activity lifecycle, the Android system manages the life of an activity for you, so you do not need to finish your own activities. Calling these methods could adversely affect the expected user experience and should only be used when you absolutely do not want the user to return to this instance of the activity.
Managing the Activity Lifecycle
Managing the lifecycle of your activities by implementing callback methods is crucial to developing a strong and flexible application. The lifecycle of an activity is directly affected by its association with other activities, its task and back stack.
An activity can exist in essentially three states:
Activity
object is retained in memory, it maintains all state and member information, and remains attached to the window manager), but can be killed by the system in extremely low memory situations.Activity
object is retained in memory, it maintains all state and member information, but is not attached to the window manager). However, it is no longer visible to the user and it can be killed by the system when memory is needed elsewhere.If an activity is paused or stopped, the system can drop it from memory either by asking it to finish (calling its finish()
method), or simply killing its process. When the activity is opened again (after being finished or killed), it must be created all over.
Implementing the lifecycle callbacks
When an activity transitions into and out of the different states described above, it is notified through various callback methods. All of the callback methods are hooks that you can override to do appropriate work when the state of your activity changes. The following skeleton activity includes each of the fundamental lifecycle methods:
public class ExampleActivity extends Activity {
@Override
public voidonCreate
(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// The activity is being created.
}
@Override
protected voidonStart()
{
super.onStart();
// The activity is about to become visible.
}
@Override
protected voidonResume()
{
super.onResume();
// The activity has become visible (it is now "resumed").
}
@Override
protected voidonPause()
{
super.onPause();
// Another activity is taking focus (this activity is about to be "paused").
}
@Override
protected voidonStop()
{
super.onStop();
// The activity is no longer visible (it is now "stopped")
}
@Override
protected voidonDestroy()
{
super.onDestroy();
// The activity is about to be destroyed.
}
}
Note: Your implementation of these lifecycle methods must always call the superclass implementation before doing any work, as shown in the examples above.
Taken together, these methods define the entire lifecycle of an activity. By implementing these methods, you can monitor three nested loops in the activity lifecycle:
- The entire lifetime of an activity happens between the call to
onCreate()
and the call toonDestroy()
. Your activity should perform setup of "global" state (such as defining layout) inonCreate()
, and release all remaining resources inonDestroy()
. For example, if your activity has a thread running in the background to download data from the network, it might create that thread inonCreate()
and then stop the thread inonDestroy()
. -
The visible lifetime of an activity happens between the call to
onStart()
and the call toonStop()
. During this time, the user can see the activity on-screen and interact with it. For example,onStop()
is called when a new activity starts and this one is no longer visible. Between these two methods, you can maintain resources that are needed to show the activity to the user. For example, you can register aBroadcastReceiver
inonStart()
to monitor changes that impact your UI, and unregister it inonStop()
when the user can no longer see what you are displaying. The system might callonStart()
andonStop()
multiple times during the entire lifetime of the activity, as the activity alternates between being visible and hidden to the user. -
The foreground lifetime of an activity happens between the call to
onResume()
and the call toonPause()
. During this time, the activity is in front of all other activities on screen and has user input focus. An activity can frequently transition in and out of the foreground—for example,onPause()
is called when the device goes to sleep or when a dialog appears. Because this state can transition often, the code in these two methods should be fairly lightweight in order to avoid slow transitions that make the user wait.
Figure 1 illustrates these loops and the paths an activity might take between states. The rectangles represent the callback methods you can implement to perform operations when the activity transitions between states.
The same lifecycle callback methods are listed in table 1, which describes each of the callback methods in more detail and locates each one within the activity's overall lifecycle, including whether the system can kill the activity after the callback method completes.
|
Called when the activity is first created. This is where you should do all of your normal static set up — create views, bind data to lists, and so on. This method is passed a Bundle object containing the activity's previous state, if that state was captured (see Saving Activity State, later).
Always followed by |
No | onStart() |
|
|
Called after the activity has been stopped, just prior to it being started again.
Always followed by |
No | onStart() |
|
|
Called just before the activity becomes visible to the user.
Followed by |
No |
onResume() or onStop()
|
|
|
Called just before the activity starts interacting with the user. At this point the activity is at the top of the activity stack, with user input going to it.
Always followed by |
No | onPause() |
|
|
Called when the system is about to start resuming another activity. This method is typically used to commit unsaved changes to persistent data, stop animations and other things that may be consuming CPU, and so on. It should do whatever it does very quickly, because the next activity will not be resumed until it returns.
Followed either by |
Yes |
onResume() or onStop()
|
|
|
Called when the activity is no longer visible to the user. This may happen because it is being destroyed, or because another activity (either an existing one or a new one) has been resumed and is covering it.
Followed either by |
Yes |
onRestart() or onDestroy()
|
|
|
Called before the activity is destroyed. This is the final call that the activity will receive. It could be called either because the activity is finishing (someone called on it), or because the system is temporarily destroying this instance of the activity to save space. You can distinguish between these two scenarios with the method. |
Yes | nothing |
The column labeled "Killable after?" indicates whether or not the system can kill the process hosting the activity at any time after the method returns, without executing another line of the activity's code. Three methods are marked "yes": (onPause()
, onStop()
, and onDestroy()
). Because onPause()
is the first of the three, once the activity is created, onPause()
is the last method that's guaranteed to be called before the process can be killed—if the system must recover memory in an emergency, then onStop()
and onDestroy()
might not be called. Therefore, you should use onPause()
to write crucial persistent data (such as user edits) to storage. However, you should be selective about what information must be retained during onPause()
, because any blocking procedures in this method block the transition to the next activity and slow the user experience.
Methods that are marked "No" in the Killable column protect the process hosting the activity from being killed from the moment they are called. Thus, an activity is killable from the time onPause()
returns to the time onResume()
is called. It will not again be killable until onPause()
is again called and returns.
Note: An activity that's not technically "killable" by this definition in table 1 might still be killed by the system—but that would happen only in extreme circumstances when there is no other recourse. When an activity might be killed is discussed more in the Processes and Threading document.
Saving activity state
The introduction to Managing the Activity Lifecycle briefly mentions that when an activity is paused or stopped, the state of the activity is retained. This is true because the Activity
object is still held in memory when it is paused or stopped—all information about its members and current state is still alive. Thus, any changes the user made within the activity are retained in memory, so that when the activity returns to the foreground (when it "resumes"), those changes are still there.
However, when the system destroys an activity in order to recover memory, the Activity
object is destroyed, so the system cannot simply resume it with its state intact. Instead, the system must recreate the Activity
object if the user navigates back to it. Yet, the user is unaware that the system destroyed the activity and recreated it and, thus, probably expects the activity to be exactly as it was. In this situation, you can ensure that important information about the activity state is preserved by implementing an additional callback method that allows you to save information about the state of your activity and then restore it when the the system recreates the activity.
The callback method in which you can save information about the current state of your activity is onSaveInstanceState()
. The system calls this method before making the activity vulnerable to being destroyed and passes it a Bundle
object. The Bundle
is where you can store state information about the activity as name-value pairs, using methods such as putString()
. Then, if the system kills your activity's process and the user navigates back to your activity, the system passes the Bundle
to onCreate()
so you can restore the activity state you saved during onSaveInstanceState()
. If there is no state information to restore, then the Bundle
passed to onCreate()
is null.
Note: There's no guarantee that onSaveInstanceState()
will be called before your activity is destroyed, because there are cases in which it won't be necessary to save the state (such as when the user leaves your activity using the BACK key, because the user is explicitly closing the activity). If the method is called, it is always called before onStop()
and possibly before onPause()
.
However, even if you do nothing and do not implement onSaveInstanceState()
, some of the activity state is restored by the Activity
class's default implementation of onSaveInstanceState()
. Specifically, the default implementation calls onSaveInstanceState()
for every View
in the layout, which allows each view to provide information about itself that should be saved. Almost every widget in the Android framework implements this method as appropriate, such that any visible changes to the UI are automatically saved and restored when your activity is recreated. For example, the EditText
widget saves any text entered by the user and the CheckBox
widget saves whether it's checked or not. The only work required by you is to provide a unique ID (with the android:id
attribute) for each widget you want to save its state. If a widget does not have an ID, then it cannot save its state.
You can also explicitly stop a view in your layout from saving its state by setting the android:saveEnabled
attribute to "false"
or by calling the setSaveEnabled()
method. Usually, you should not disable this, but you might if you want to restore the state of the activity UI differently.
Although the default implementation of onSaveInstanceState()
saves useful information about your activity's UI, you still might need to override it to save additional information. For example, you might need to save member values that changed during the activity's life (which might correlate to values restored in the UI, but the members that hold those UI values are not restored, by default).
Because the default implementation of onSaveInstanceState()
helps save the state of the UI, if you override the method in order to save additional state information, you should always call the superclass implementation of onSaveInstanceState()
before doing any work.
Note: Because onSaveInstanceState()
is not guaranteed to be called, you should use it only to record the transient state of the activity (the state of the UI)—you should never use it to store persistent data. Instead, you should use onPause()
to store persistent data (such as data that should be saved to a database) when the user leaves the activity.
A good way to test your application's ability to restore its state is to simply rotate the device so that the screen orientation changes. When the screen orientation changes, the system destroys and recreates the activity in order to apply alternative resources that might be available for the new orientation. For this reason alone, it's very important that your activity completely restores its state when it is recreated, because users regularly rotate the screen while using applications.
Handling configuration changes
Some device configurations can change during runtime (such as screen orientation, keyboard availability, and language). When such a change occurs, Android restarts the running Activity (onDestroy()
is called, followed immediately by onCreate()
). The restart behavior is designed to help your application adapt to new configurations by automatically reloading your application with alternative resources that you've provided. If you design your activity to properly handle this event, it will be more resilient to unexpected events in the activity lifecycle.
The best way to handle a configuration change, such as a change in the screen orientation, is to simply preserve the state of your application using onSaveInstanceState()
and onRestoreInstanceState()
(or onCreate()
), as discussed in the previous section.
For a detailed discussion about configuration changes that happen at runtime and how you should handle them, read Handling Runtime Changes.
Coordinating activities
When one activity starts another, they both experience lifecycle transitions. The first activity pauses and stops (though, it won't stop if it's still visible in the background), while the other activity is created. In case these activities share data saved to disc or elsewhere, it's important to understand that the first activity is not completely stopped before the second one is created. Rather, the process of starting the second one overlaps with the process of stopping the first one.
The order of lifecycle callbacks is well defined, particularly when the two activities are in the same process and one is starting the other. Here's the order of operations that occur when Activity A starts Acivity B:
- Activity A's
onPause()
method executes. - Activity B's
onCreate()
,onStart()
, andonResume()
methods execute in sequence. (Activity B now has user focus.) - Then, if Activity A is no longer visible on screen, its
onStop()
method executes.
This predictable sequence of lifecycle callbacks allows you to manage the transition of information from one activity to another. For example, if you must write to a database when the first activity stops so that the following activity can read it, then you should write to the database during onPause()
instead of during onStop()
.
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强化学习的主要算法:包括Q-learning、SARSA、DQN、A3C、TRPO、PPO和SAC等。这些算法各有特点,适用于不同的场景和任务。例如,Q-learning和SARSA是基于值函数的强化学习算法,旨在学习最优策略以最大化累积奖励;而DQN则是深度强化学习算法,使用神经网络来估计值函数,并通过反向传播算法更新网络参数。 强化学习在多个领域具有广泛应用。在自动驾驶系统中,强化学习可以帮助车辆感知周围环境并做出决策,实现自主行驶。在医疗领域,强化学习可以用于辅助医生进行病例分析、诊断和治疗方案制定,提高医疗服务的准确性和效率。此外,强化学习还在智能物流和仓储管理、金融投资决策等领域发挥着重要作用。
封面 标题:基于物联网的智能家居系统年度总结 报告人信息:[姓名]、[职位/角色]、[所属机构/公司] 日期:[具体日期] 目录 引言 年度工作回顾 系统进展与亮点 技术创新与应用 市场反馈与用户评价 存在问题与挑战 未来展望与计划 结束语与感谢 一、引言 简要介绍智能家居系统的重要性和发展趋势 回顾本年度的工作目标和重点 二、年度工作回顾 系统建设与维护 完成的项目与里程碑 系统稳定性与可靠性提升 团队建设与培训 团队成员构成与职责 培训与技能提升活动 合作伙伴与资源整合 与供应商、合作伙伴的合作情况 资源整合与利用 三、系统进展与亮点 功能扩展与优化 新增功能介绍与效果评估 现有功能的优化与改进 用户体验提升 界面设计与交互优化 用户反馈与改进措施 四、技术创新与应用 物联网技术的应用 传感器与通信技术的升级 大数据分析与应用 智能家居的智能化管理 自动化控制与节能策略 安全防护与预警系统 五、市场反馈与用户评价 市场反馈分析 市场需求与竞争态势 市场占有率与增长趋势 用户评价总结 用户满意度调查结果
numpy安装
Python库是一组预先编写的代码模块,旨在帮助开发者实现特定的编程任务,无需从零开始编写代码。这些库可以包括各种功能,如数学运算、文件操作、数据分析和网络编程等。Python社区提供了大量的第三方库,如NumPy、Pandas和Requests,极大地丰富了Python的应用领域,从数据科学到Web开发。Python库的丰富性是Python成为最受欢迎的编程语言之一的关键原因之一。这些库不仅为初学者提供了快速入门的途径,而且为经验丰富的开发者提供了强大的工具,以高效率、高质量地完成复杂任务。例如,Matplotlib和Seaborn库在数据可视化领域内非常受欢迎,它们提供了广泛的工具和技术,可以创建高度定制化的图表和图形,帮助数据科学家和分析师在数据探索和结果展示中更有效地传达信息。
Python库是一组预先编写的代码模块,旨在帮助开发者实现特定的编程任务,无需从零开始编写代码。这些库可以包括各种功能,如数学运算、文件操作、数据分析和网络编程等。Python社区提供了大量的第三方库,如NumPy、Pandas和Requests,极大地丰富了Python的应用领域,从数据科学到Web开发。Python库的丰富性是Python成为最受欢迎的编程语言之一的关键原因之一。这些库不仅为初学者提供了快速入门的途径,而且为经验丰富的开发者提供了强大的工具,以高效率、高质量地完成复杂任务。例如,Matplotlib和Seaborn库在数据可视化领域内非常受欢迎,它们提供了广泛的工具和技术,可以创建高度定制化的图表和图形,帮助数据科学家和分析师在数据探索和结果展示中更有效地传达信息。
进制转换器,支持对有符号数进行转换。可以在10进制数、16进制数、2进制数之间相互转换。 亮点:16进制数/2进制数可转换为有符号数整型。
伺服
Python库是一组预先编写的代码模块,旨在帮助开发者实现特定的编程任务,无需从零开始编写代码。这些库可以包括各种功能,如数学运算、文件操作、数据分析和网络编程等。Python社区提供了大量的第三方库,如NumPy、Pandas和Requests,极大地丰富了Python的应用领域,从数据科学到Web开发。Python库的丰富性是Python成为最受欢迎的编程语言之一的关键原因之一。这些库不仅为初学者提供了快速入门的途径,而且为经验丰富的开发者提供了强大的工具,以高效率、高质量地完成复杂任务。例如,Matplotlib和Seaborn库在数据可视化领域内非常受欢迎,它们提供了广泛的工具和技术,可以创建高度定制化的图表和图形,帮助数据科学家和分析师在数据探索和结果展示中更有效地传达信息。
全国企业家活动日ppt模板x.pptx
Python库是一组预先编写的代码模块,旨在帮助开发者实现特定的编程任务,无需从零开始编写代码。这些库可以包括各种功能,如数学运算、文件操作、数据分析和网络编程等。Python社区提供了大量的第三方库,如NumPy、Pandas和Requests,极大地丰富了Python的应用领域,从数据科学到Web开发。Python库的丰富性是Python成为最受欢迎的编程语言之一的关键原因之一。这些库不仅为初学者提供了快速入门的途径,而且为经验丰富的开发者提供了强大的工具,以高效率、高质量地完成复杂任务。例如,Matplotlib和Seaborn库在数据可视化领域内非常受欢迎,它们提供了广泛的工具和技术,可以创建高度定制化的图表和图形,帮助数据科学家和分析师在数据探索和结果展示中更有效地传达信息。
2024生态环境保护主题活动宣传服务项目方案ss.pptx
国际知名家居品牌整合营销全案ss.pptx
**C/C++课程设计项目合集** 本次提供的C/C++课程设计项目包括:KTV歌曲系统、学生档案管理系统、个人收支系统以及职工管理系统。这些项目不仅适用于课程设计,还可作为实际应用的初步探索。每个项目均经过精心设计和测试,确保代码质量和功能的完整性。 * **KTV歌曲系统**:实现了歌曲的增删改查、播放控制以及用户管理等功能,适用于各类KTV场所。 * **学生档案管理系统**:提供学生信息的录入、查询、修改和删除功能,帮助教育机构高效管理学生档案。 * **个人收支系统**:以用户为中心,记录日常收入和支出,并生成详细的统计报告,方便个人理财。 * **职工管理系统**:针对企业需求,对职工信息进行集中管理,支持多条件查询和报表生成。 这些项目采用C/C++编程语言,基于面向对象的编程思想,充分利用了现代软件工程的技术和方法。代码结构清晰,注释详细,易于理解和维护。同时,为了满足不同用户的需求,项目提供了灵活的定制选项,可以根据实际需求进行二次开发。
使用方法: 将脚本保存为iOSAppBuildAndDeploy.sh文件。 将YourProject.xcodeproj替换为你的Xcode项目文件路径。 将YourScheme替换为你的Xcode项目的Scheme名称。 创建一个ExportOptions.plist文件,并配置导出选项(例如,方法、团队ID等),然后指定其路径到EXPORT_OPTIONS_PLIST变量。 打开终端,导航到包含该脚本的目录。 给脚本执行权限:chmod +x iOSAppBuildAndDeploy.sh。 运行脚本:./iOSAppBuildAndDeploy.sh。 注意事项: 确保你的Mac上已经安装了Xcode和相应的命令行工具。 根据你的需求,你可能需要修改或扩展脚本,例如添加上传IPA到TestFlight或其他分发渠道的代码。 脚本中的ExportOptions.plist文件是Xcode构建过程中用于配置导出选项的关键文件。你需要根据你的应用分发需求来创建和配置这个文件。 如果脚本执行过程中遇到错误,请检查Xcode构建日志和脚本输出信息,以便定位问题。
2000-2021年各省产业集聚度/就业密度数据 1、时间:2000-2021年 2、来源:人口就业统计年鉴、各省年鉴 3、指标:就业人数、行政区划面积、产业集聚度/就业密度 4、范围:31省 5、计算说明:产业集聚度/就业密度=就业人数/行政区划面积
QYResearch是全球知名的大型咨询公司,行业涵盖各高科技行业产业链细分市场,横跨如半导体产业链(半导体设备及零部件、半导体材料、集成电路、制造、封测、分立器件、传感器、光电器件)、光伏产业链(设备、硅料/硅片、电池片、组件、辅料支架、逆变器、电站终端)、新能源汽车产业链(动力电池及材料、电驱电控、汽车半导体/电子、整车、充电桩)、通信产业链(通信系统设备、终端设备、电子元器件、射频前端、光模块、4G/5G/6G、宽带、IoT、数字经济、AI)、先进材料产业链(金属材料、高分子材料、陶瓷材料、纳米材料等)、机械制造产业链(数控机床、工程机械、电气机械、3C自动化、工业机器人、激光、工控、无人机)、食品药品、医疗器械、农业等。 邮箱:market@qyresearch.com
高级网络人才培训专家_X00070002 第29章 配置HDLC