clear

问题 I understand that the complexity of the clear() operation is linear in the size of the container, because the destructors must be called. But what about primitive types (and POD)? It seems the best thing to do would be to set the vector size to 0, so that the complexity is constant. If this is possible, is it also possible for std::unordered_map? 回答1: It seems the best thing to do would be to set the vector size to 0, so that the complexity is constant. In general, the complexity of resizing

问题 I don't want to let Settings clear my app sharedPreference by anyone: is it possible? 回答1: hey buddy i found an answer here is a way to prevent data being cleared from Shared Preference Add android:manageSpaceActivity=".ActivityOfMyChoice" to the application tag of your Manifest like: <application android:label="MyApp" android:icon="@drawable/icon" android:manageSpaceActivity=".ActivityOfMyChoice"> Then instead of "Clear Data" , there is a button for "Manage Space" which launches

问题 I installed Cygwin, choosing a fairly minimal set of packages. In a terminal, I tried to do 'clear' to clear the terminal, but I get bash: clear: command not found How do I get this to work? 回答1: Install the Cygwin package ncurses ; it is in the Utils category. 回答2: This should do: alias clear='printf "\033c"' 回答3: just use this shortcut: Alt+F8 and Ctrl-L to skip page 回答4: It's nice to have the clear.exe program for bash script files, so: Windows Cygwin detail for clear.exe program command.

问题 Using Java (1.6) is it better to call the clear() method on a List or just re-instantiate the reference? I have an ArrayList that is filled with an unknown number of Objects and periodically "flushed" - where the Objects are processed and the List is cleared. Once flushed the List is filled up again. The flush happens at a random time. The number within the List can potentially be small (10s of Objects) or large (millions of objects). So is it better to have the "flush" call clear() or new

问题 I am reusing ImageView s for my displays, but at some point I don't have values to put it. So how to clear an ImageView in Android? I've tried: mPhotoView.invalidate(); mPhotoView.setImageBitmap(null); None of them have cleared the view, it still shows previous image. 回答1: I used to do it with the dennis.sheppard solution: viewToUse.setImageResource(0); it works but it is not documented so it isn't really clear if it effects something else in the view (you can check the ImageView code if you

问题 Can any body please tell me what code is used for clear screen in Java? For example in C++ system("CLS"); What code is used in Java for clear screen? Thanks! 回答1: Since there are several answers here showing non-working code for Windows, here is a clarification: Runtime.getRuntime().exec("cls"); This command does not work, for two reasons: There is no executable named cls.exe or cls.com in a standard Windows installation that could be invoked via Runtime.exec , as the well-known command cls

问题 I want to partially clear the canvas. in this project, I cannot clear the canvas fully ,I have to clear the canvas partially.I have tried to clear the canvas by its original x and y(the position before the movement),but it does not work. let canvas = document.getElementById("canvas"); let context = canvas.getContext("2d"); var enemys = []; let enemyLimitObj = { enemyLimitDown: 470, enemyLimitLeft: 30, enemyLimitRight: 670, enemyLimitTop: 30 }; class Enemy { constructor(x) { (this.x = x),

问题 This is way-too-basic question, but the behavior of the div on my website leaves me perplexed. I've experienced identical issue before, so I am sure I am doing something wrong, consistently, or misunderstanding some fundamental CSS rule. Question: Why does the red div tag near the bottom right of the site clears its left counterpart? There's no "clear" rule applied to it! Here's the html: <div id="home-left"> <?php echo "Some php=generated content"; ?> </div> <!-- END HOME-LEFT --> <div id=

问题 I have a problem with the flickering. Here is my code. public class Tutorial2D3 extends Activity { Panel panel; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); panel = new Panel(this); setContentView(panel); } @Override public boolean onCreateOptionsMenu(Menu menu) { menu.add(1, 1, 1, "Clean Canvas"); return super.onCreateOptionsMenu(menu); } @Override public boolean onMenuItemSelected(int

问题 New in image editing.. i want to develop an app like https://play.google.com/store/apps/details?id=com.outthinking.bgeraser and looking for main functionality which is removing background of any image help me... Thanks in advance.. 回答1: I guess your problem is, that you don't exactly know what you are looking for. Just search for: Background Subtraction Thats how it is called. You can find lots of articles about that. Come back if you have more detailed questions. 来源： https://stackoverflow