Qt入門－下拉列表框QComboBox類

     QComboBox是QT GUI中的下拉列表框。

class Q_GUI_EXPORT QComboBox : public QWidget
{
    Q_OBJECT

常用方法和屬性：

（1）addItems

void addItems ( const QStringList & texts )

在QComboBox的最後添加一項。

（2）count

int count () const

返回列表項總數。

（3）currentIndex

int currentIndex () const

當前顯示的列表項序號。

（4）currentText

QString currentText () const

返回當前顯示的文本。

（5）insertItem

void insertItem ( int index, const QString & text, const QVariant & userData = QVariant() )

void insertItem ( int index, const QIcon & icon, const QString & text, const QVariant & userData = QVariant() )

void insertItems ( int index, const QStringList & list )

插入一項或多項至序號index處。

（6）insertSeparator

void insertSeparator ( int index )

在序號爲index的項前插入分隔線

（7）setItemText

void setItemText ( int index, const QString & text )

改變序號爲index項的文本。

示例：

Window.h

#ifndef __WINDOW_H__
#define __WINDOW_H__

#include <QMainWindow>
#include <QPushButton>
#include <QLineEdit>
#include <QLayout>
#include <QLabel>
#include <QComboBox>
#include <QMessageBox>
#include <QDialog>


class Window : public QMainWindow
{
    Q_OBJECT

public:
    Window(QWidget *parent = NULL):QMainWindow(parent)
    {
        QGridLayout *gridLayout = new QGridLayout;
        gridLayout->setColumnStretch(0, 1);
        gridLayout->setColumnStretch(1, 3);

        gridLayout->setMargin(10);

        QLabel *lbl_caption = new QLabel(QWidget::tr("Sex:"));
        cbo_sex = new QComboBox();

        cbo_sex->addItem(QWidget::tr("male"));
        cbo_sex->addItem(QWidget::tr("female"));
        cbo_sex->insertItem(2, tr("Insert item"));
        cbo_sex->insertSeparator(2);

        gridLayout->addWidget(lbl_caption, 0, 0);
        gridLayout->addWidget(cbo_sex, 0, 1);

        QHBoxLayout *bomLayout = new QHBoxLayout;
        QPushButton *btn = new QPushButton(QWidget::tr("Select"));
        bomLayout->addStretch();
        bomLayout->addWidget(btn);
        bomLayout->addStretch();

        QVBoxLayout *mainLayout = new QVBoxLayout;
        mainLayout->addLayout(gridLayout);
        mainLayout->addLayout(bomLayout);

        QWidget *mainWidget = new QWidget;
        mainWidget->setLayout(mainLayout);

        setCentralWidget(mainWidget);

        connect(cbo_sex, SIGNAL(currentIndexChanged(const QString &)), this, SLOT(on_sel_sex(const QString &)));
        connect(btn, SIGNAL(clicked()), this, SLOT(on_click_sel()));
    }

private:
    QComboBox *cbo_sex;

private slots:
    void on_sel_sex(const QString &text)
    {
        QString str;
        str = "You select " + text;
        QMessageBox::information(this, tr("Info"), str);
    }

    void on_click_sel()
    {
        QString str;
        str = "You select " + cbo_sex->currentText();
        QMessageBox::information(this, tr("Info"), str);
    }

};


#endif

main.cpp

#include <QApplication>
#include <QDialog>
#include "Window.h"



int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Window *mainWindow = new Window;



    mainWindow->resize(200, 100);
    mainWindow->setWindowTitle(QWidget::tr("Qt Test"));
    mainWindow->show();

    return a.exec();
}

編譯運行，界面如下：