为什么我不能以下列方式重载类型JTextField的类成员:`
private JTextField m_oFilename=new JTextField();
public JTextField filename()
{ return this.m_oFilename; }
public String filename()
{ return this.m_oFilename.getText(); }
我是java的新手,我必须创建这个程序,我不知道从哪里开始.有人可以帮助我做什么以及如何编写代码来开始？
编写一个模拟收银机的程序.提示用户输入三个项目的价格.将它们添加到一起以获得小计.确定小计的税(6%).查找销售小计加税的总金额.显示每个项目的价格,小计金额,税额和最终金额.
到目前为止我有这个:
package register;
import java.util.Scanner;
public class Register {
public static void main(String[] args) {
Scanner price = new Scanner(System.in);
System.out.print("Please enter a price for item uno $");
double priceuno = price.nextDouble();
System.out.print("Please enter a price for item dos $" );
double pricedos = price.nextDouble();
System.out.print("Please enter a price for item tres $");
double pricetres = price.nextDouble();
double total = ((priceuno) + (pricedos) + (pricetres));
System.out.println("The subtotal is $" + total);
double tax = .06;
double totalwotax = …我有以下简单的QML组合框:
import QtQuick 2.0
import QtQuick.Controls 1.4
import si.mikroelektronika 1.0
Item
{
id: ueStaffSelector
width: 256
height: 96
ComboBox
{
model: uePeopleModel
editable: false
anchors.fill: parent
} // ComboBox
} // Item
正如你所看到的,我分配uePeopleModel给它,它已经在应用程序中正常工作.应用程序执行后,我会收到以下QML运行时错误:
file:///opt/QtOpenSource55/5.5/gcc_64/qml/QtQuick/Controls/ComboBox.qml:562:ReferenceError:modelData未定义文件:///opt/QtOpenSource55/5.5/gcc_64/qml/QtQuick/Controls/ ComboBox.qml:562:ReferenceError:modelData未定义file:///opt/QtOpenSource55/5.5/gcc_64/qml/QtQuick/Controls/ComboBox.qml:562:ReferenceError:modelData未定义file:/// opt/QtOpenSource55/5.5/gcc_64/qml/QtQuick/Controls/ComboBox.qml:562:ReferenceError:modelData未定义文件:///opt/QtOpenSource55/5.5/gcc_64/qml/QtQuick/Controls/ComboBox.qml:562:ReferenceError :modelData未定义
整个应用程序在main.cpp中构建:
#include <QtQml>
#include <QApplication>
#include <QQmlApplicationEngine>
#include <QTimer>
#include "database/uepeoplemodel.h"
#include "core/ueapplicationstatus.h"
#include "core/uedatabaseconnectionstatus.h"
#include "core/uebluetoothmanager.h"
#include "core/uebluetoothprinterconnectionstatus.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QQmlApplicationEngine engine;
UeApplicationStatus* ueApplicationStatus=new UeApplicationStatus(qApp);
UePeopleModel* uePeopleModel=new UePeopleModel(qApp);
UeBluetoothManager* ueBtManager=new UeBluetoothManager(qApp); …我将文件转换为通过的处理时间超过 2 秒120 MB geojsonprotobufMapnikVector Tile 节点绑定。
在另一端提供原始geosjon文件需要不到 200 毫秒。
正常吗？如果是，那么提供矢量切片有什么意义geojson（我正在查看它mapbox-gl-js）？
这是我的代码的摘录：
// Load GeoJson into memory
var fs = require("fs");
var content = JSON.parse(fs.readFileSync("us_counties.json"));
// Initialise Mapnik and mercator object
mapnik.register_default_fonts();
mapnik.register_default_input_plugins();
var mercator = new SphericalMercator({
size: 256
});
// Vector Tile Router
router.get('/:z/:x/:y.pbf', function(req, res) {
var bbox = mercator.bbox(
+req.params.x,
+req.params.y,
+req.params.z,
false,
'4326'
);
// Convert GEOJSON to protobuf VectorTile …在我继承自同事的项目中,我有基本的c ++类,带有头和实现.为了便于理解,我将提供示例情况,因为代码本身太大了: bthidtransport.h:
class BtHidTransport
{
public:
BtHidTransport(); // constructor
protected:
virtual ~BtHidTransport(); // destructor
} // BtHidTransport
bthidtransport.cpp:
BtHidTransport::BtHidTransport
{
} // constructor
BtHidTransport::~BtHidTransport()
{
} // destructor
这是基类,现在我们有了派生类头:
bthidtransportfixes.h:
#include "bthidtransport.h"
class BtHidTransportFixes : public BtHidTransport
{
BtHidTransportFixes(); // constructor
virtual ~BtHidTransportFixes(); // destructor
} // BtHidTransportFixes
但是,在特定项目中,BtHidTransportFixes没有实现(.cpp)文件.项目本身构建没有错误.如果我在运行时从类实例化新对象:
BtHidTransport* createdObject=new BtHidTransportFixes();
和BtHidTransportFixes没有实现(.cpp)文件,父类的执行顺序是什么？我正在使用Eclipse 4.3.2 for Windows(主机操作系统是Windows 7 64位Ultimate)和ARM DS-5 5.20.2编译器.BtHidTransportFixes项目中没有任何实现,我在 …
我有以下代码块:
private void saveAs()
{
CDocument currentDocument=this.panelMain().openedDocuments().get(this.panelMain().openedDocuments().size()-1);
StyledDocument contents=currentDocument.getStyledDocument();
DefaultEditorKit kit=new DefaultEditorKit();
JFileChooser chooserSaveAs=new JFileChooser();
chooserSaveAs.setDialogTitle("Save as ...");
if(chooserSaveAs.showSaveDialog(this)==JFileChooser.APPROVE_OPTION)
{
String strNewFilename=chooserSaveAs.getSelectedFile().getName();
BufferedOutputStream out;
try
{
out=new BufferedOutputStream(new FileOutputStream(strNewFilename));
kit.write(out,
contents,
contents.getStartPosition().getOffset(),
contents.getLength());
out.close();
}
catch(IOException | BadLocationException ex)
{
Logger.getLogger(CFrameMain.class.getName()).log(Level.SEVERE,
null,
ex);
}
}
}
一旦执行,此代码不会生成任何异常,但我无法在任何地方找到磁盘上保存的文件(我使用Total Commander搜索本地磁盘).为什么没有生成文件？我目前正在使用Windows 7 Ultimate,我试图保存到已登录用户的桌面(因为可能存在访问冲突问题......)？
我正在研究基于此示例的异步多线程服务器.现在,我有以下方法:
void UeClient::ueSlotReadyRead()
{
QList<QVariant> incomingData=QList<QVariant>();
QByteArray incomingMessage=this->ueSocket()->readAll();
UePosCommProtocolArch::UeCommand incomingCommand=UePOSCommProtocol::ueDecodeCommand(incomingMessage,
incomingData);
UeTask* ueTask=new UeTask("testDb",
"testUsername",
"testPassword",
"localhost",
"3306",
incomingCommand);
connect(ueTask,
SIGNAL(ueSignalTaskFinished(UePosCommProtocolArch::UeCommand,
QByteArray)),
this,
SLOT(ueSlotFetchData(UePosCommProtocolArch::UeCommand,
QByteArray)),
Qt::QueuedConnection);
QThreadPool::globalInstance()->start(ueTask);
} // ueSlotReadyRead
我得到以下运行时警告/错误QtCreator:
QObject :: connect:在../../../net/ueclient.cpp:55中没有这样的信号UeTask :: ueSignalTaskFinished(UePosCommProtocolArch :: UeCommand,QByteArray)
这是UeTask类头文件,我们可以从中看到ueSignalTaskFinished(UePosCommProtocolArch::UeCommand& executedCommand, QByteArray& fetchedData); IS声明:
#ifndef UETASK_H
#define UETASK_H
#include <QObject>
#include <QRunnable>
#include <QSqlDatabase>
#include <QSqlError>
#include <QUuid>
#include <QString>
#include <QSqlQuery>
#include <QSqlRecord>
#include <QVariant>
#include <QJsonDocument>
#include <QJsonValue>
#include <QJsonObject> …