Question

我正在尝试制作某门学科缺席的学生的成绩单例如，如果学生缺席两个科目，则输出应为：

subject    marks
sub1       78
sub2       84
sub3       Absent
sub4       Absent
sub5       34
-------------------
Total:xx   Average:xx



import java.util.*;
public class ReportCard {

    public static void main(String[] args)
    {
        Scanner sc=new Scanner(System.in);

        System.out.print("Enter Student name: ");
        String name=sc.nextLine();
        System.out.print("Enter number of Subject: ");
            int no=sc.nextInt();

        String[] marks =new String[no];
        for(int i=0;i<marks.length;i++)
        {
            System.out.print("Enter marks of subject"+(i+1)+":");
            marks[i]=sc.nextLine();
        }

        reportCard(marks, name);
        sc.close();

    }
    static void reportCard(String[] marks,String name)
    {
    System.out.print("---------------------------------------\n");
        System.out.print("\t REPORT CARD\n");
        System.out.println("NAME:"+name);
    System.out.println("---------------------------------------\n");
    System.out.println("SUBJECT\t\t       MARKS");
    int total=0;
    for(int i=0;i<marks.length;i++)
        {
         if(marks[i]=="Absent")
            {
              break;
            }
            else
            {
             total=total+marks[i]   
            }

         System.out.println("Subject "+(i+1)+"\t\t"+marks[i]);
        }
     System.out.print("---------------------------------------\n");
     float avg;
     avg=((float)total/marks.length);
     System.out.print("Total: "+total+"\t Average:"+avg);

    }
}

字符串不能转换为int

Answer 1

Integer.parseInt（[STRING GOES HERE]）将返回一个整数。

Answer 2

total=total+marks[i]-此行取一个int（总计）并将其设置为等于自身加marks[i]。 marks[i]是一个字符串，因为它来自字符串数组。

看来marks唯一不能转换为int的值是“不存在”，因此在检查以确保不存在该值之后，可以将此值转换为一个int，以便可以将其添加到您的int总数中。

尝试在parseInt()周围添加marks[i]，使行total=total+parseInt(marks[i])。请务必确保您强制转换的值只是整数的String版本，否则会遇到问题。

Answer 3

使用java包装器类可以很容易地将字符串转换为有效的整数。您可以进一步了解他们here！

例如：

String number = "10";
int result = Integer.parseInt(number);          
System.out.println(result);

这里Integer是包装器类。请注意int和Integer之间的区别

<-进行投票，如果有帮助的话-> ：）

Answer 4

您需要将等级转换为数值。但是，您还需要注意确保该值实际上是数字。

root@08c7a05c8129:/usr/lib/Wt/examples/hello# ls /usr/include/Wt
Auth                       WBatchEditProxyModel       WDateValidator            WHTML5Audio          WLocalizedStrings         WPopupWidget           WSslInfo            WTimePicker
Chart                      WBoostAny                  WDefaultLayout            WHTML5Video          WLogger                   WProgressBar           WStackedWidget      WTimeValidator
Dbo                        WBootstrapTheme            WDefaultLoadingIndicator  WIOService           WMatrix4x4                WPushButton            WStandardItem       WTimer
Ext                        WBorder                    WDialog                   WIcon                WMeasurePaintDevice       WRadioButton           WStandardItemModel  WTimerWidget
Http                       WBorderLayout              WDllDefs.h                WIconPair            WMediaPlayer              WRandom                WStatelessSlot      WToolBar
Json                       WBoxLayout                 WDoubleSpinBox            WIdentityProxyModel  WMemoryResource           WRasterImage           WStreamResource     WTransform
Mail                       WBreak                     WDoubleValidator          WImage               WMenu                     WReadOnlyProxyModel    WString             WTree
Payment                    WBrush                     WEnvironment              WInPlaceEdit         WMenuItem                 WRectArea              WStringListModel    WTreeNode
Render                     WButtonGroup               WEvent                    WIntValidator        WMessageBox               WRectF                 WStringStream       WTreeTable
Utils                      WCalendar                  WException                WInteractWidget      WMessageResourceBundle    WRegExp                WStringUtil         WTreeTableNode
WAbstractArea              WCanvasPaintDevice         WFileResource             WItemDelegate        WMessageResources         WRegExpValidator       WSubMenuItem        WTreeView
WAbstractGLImplementation  WCheckBox                  WFileUpload               WItemSelectionModel  WModelIndex               WResource              WSuggestionPopup    WVBoxLayout
WAbstractItemDelegate      WCircleArea                WFitLayout                WJavaScript          WNavigationBar            WScrollArea            WSvgImage           WValidationStatus
WAbstractItemModel         WClientGLWidget            WFlags                    WJavaScriptPreamble  WObject                   WScrollBar             WTabWidget          WValidator
WAbstractItemView          WColor                     WFlashObject              WJavaScriptSlot      WOverlayLoadingIndicator  WSelectionBox          WTable              WVector3
WAbstractListModel         WCombinedLocalizedStrings  WFont                     WLabel               WPaintDevice              WServer                WTableCell          WVector4
WAbstractMedia             WComboBox                  WFontMetrics              WLayout              WPaintedWidget            WServerGLWidget        WTableColumn        WVectorImage
WAbstractProxyModel        WCompositeWidget           WFormModel                WLayoutItem          WPainter                  WShadow                WTableRow           WVideo
WAbstractSpinBox           WConfig.h                  WFormWidget               WLayoutItemImpl      WPainterPath              WSignal                WTableView          WViewWidget
WAbstractTableModel        WContainerWidget           WGLWidget                 WLength              WPanel                    WSignalMapper          WTemplate           WVirtualImage
WAbstractToggleButton      WCssDecorationStyle        WGenericMatrix            WLengthValidator     WPdfImage                 WSlider                WTemplateFormView   WVmlImage
WAccordionLayout           WCssStyleSheet             WGlobal                   WLineEdit            WPen                      WSocketNotifier        WText               WWebWidget
WAggregateProxyModel       WCssTheme                  WGoogleMap                WLineF               WPoint                    WSortFilterProxyModel  WTextArea           WWidget
WAnchor                    WDate                      WGradient                 WLink                WPointF                   WSound                 WTextEdit           WWidgetItem
WAnimation                 WDateEdit                  WGridLayout               WLoadingIndicator    WPolygonArea              WSpinBox               WTheme
WApplication               WDatePicker                WGroupBox                 WLocalDateTime       WPopupMenu                WSplitButton           WTime
WAudio                     WDateTime                  WHBoxLayout               WLocale              WPopupMenuItem            WSslCertificate        WTimeEdit

运行上述命令时，可以输入整数或字符串。它将相应地处理它们。如果Scanner scan = new Scanner(System.in); String str; while (!(str = scan.nextLine()).equalsIgnoreCase("end")) { int grade; try { grade = Integer.parseInt(str); System.out.println("numeric grade = " + grade); } catch (IllegalArgumentException ie) { System.out.println("No grade - " + str); } }方法尝试将单词转换为parseInt，则会抛出int，并对其进行适当的捕获和处理。

Answer 5

尝试与此一起工作：

import java.util.*;

import com.sun.jndi.url.iiop.iiopURLContext;

import sun.audio.ContinuousAudioDataStream;
public class Main {

    public static void main(String[] args)
    {
        Scanner sc=new Scanner(System.in);

        System.out.print("Enter Student Name: ");
        String name=sc.nextLine();
        System.out.print("Enter Number of Subjects: ");
        int no=sc.nextInt();

        sc.nextLine();

        String[] marks =new String[no];
        for(int i=0;i<marks.length;i++)
        {
            System.out.print("Enter marks for subject "+(i+1)+": ");
            marks[i]=sc.nextLine();
        }

        reportCard(marks, name);
        sc.close();

    }
    static void reportCard(String[] marks,String name)
    {
    System.out.print("---------------------------------------\n");
        System.out.print("\t REPORT CARD\n");
        System.out.println("NAME:"+name);
    System.out.println("---------------------------------------\n");
    System.out.println("SUBJECT\t\t       MARKS");

    int total=0;

    for(int i=0;i<marks.length;i++)
        {
         if(i=="Absent")
            {
              break;
            }
            else
            {
             total = total + Integer.parseInt(marks[i]);  
            }

         System.out.println("Subject "+(i+1)+"\t\t"+marks[i]);
        }
     System.out.print("---------------------------------------\n");
     float avg;
     avg=((float)total/marks.length);
     System.out.print("Total: "+total+"\t Average:"+avg);

    }
}

Answer 6

1-创建一个类型为string的数组StringArray

string[] StringArray = new string[] {"1","2","3"};

2-1-创建一个类型为int的数组IntArray

int[] IntArray = new int[StringArray.Length];

3编写此代码以转换

    for (int i = 0; i < IntArray.Length; i++)
    {
        IntArray[i] = int.Parse(StringArray[i]);
    }

Answer 7

lambda表达式将 total 的计算与表格打印分开：

…
System.out.println( "SUBJECT\t\t MARKS" );

for( int i = 0; i < marks.length; i++ ) {
  System.out.println( "Subject " + (i + 1) + "\t\t" + marks[i] );
}       
System.out.print( "---------------------------------------\n" );
int total = Stream.of( marks ).filter( m -> ! "Absent".equals( m ) ).collect(
    Collectors.summingInt( Integer::parseInt ) );

float avg = ((float)total / marks.length);
System.out.print( "Total: " + total + "\t Average:" + avg ); // Total: 196 Average:39.2

如果marks[]包含空字符串，则lambda表达式将失败，并故意NumberFormatException

我想将String数组转换为int数组以显示总数

7 个答案: