Qt入门－下拉列表框QComboBox类

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QComboBox是QT GUI中的下拉列表框。

class Q_GUI_EXPORT QComboBox : public QWidget{    Q_OBJECT

常用方法和属性：

（1）addItems

void addItems ( const QStringList & texts )

在QComboBox的最后添加一项。

（2）count

int count () const

返回列表项总数。

（3）currentIndex

int currentIndex () const

当前显示的列表项序号。

（4）currentText

QString currentText () const

返回当前显示的文本。

（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 )

插入一项或多项至序号index处。

（6）insertSeparator

void insertSeparator ( int index )

在序号为index的项前插入分隔线

（7）setItemText

void setItemText ( int index, const QString & text )

改变序号为index项的文本。

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_OBJECTpublic: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();}

编译运行，界面如下：