判断当前CardLayout问题

[jmfish]

一个JPanel定义为CardLayout，有3个Card
如何在另一个JPanel里判断当前显示的是哪一个Card？
if(某个选中)添什么？
{……}

[rocandroc]

//给你一个源程序，参考一下



// Java core packages
import java.awt.*;
import java.awt.event.*;

// Java extension packages
import javax.swing.*;

public class CardDeck extends JFrame implements ActionListener {

private CardLayout cardManager;
private JPanel deck;
private JButton controls[];
private String names[] = { "First card", "Next card",
"Previous card", "Last card" };

// set up GUI
public CardDeck()
{
super( "CardLayout " );

Container container = getContentPane();

// create the JPanel with CardLayout
deck = new JPanel();
cardManager = new CardLayout();
deck.setLayout( cardManager );

// set up card1 and add it to JPanel deck
JLabel label1 =
new JLabel( "card one", SwingConstants.CENTER );
JPanel card1 = new JPanel();
card1.add( label1 );
deck.add( card1, label1.getText() ); // add card to deck

// set up card2 and add it to JPanel deck
JLabel label2 =
new JLabel( "card two", SwingConstants.CENTER );
JPanel card2 = new JPanel();
card2.setBackground( Color.yellow );
card2.add( label2 );
deck.add( card2, label2.getText() ); // add card to deck

// set up card3 and add it to JPanel deck
JLabel label3 = new JLabel( "card three" );
JPanel card3 = new JPanel();
card3.setLayout( new BorderLayout() );
card3.add( new JButton( "North" ), BorderLayout.NORTH );
card3.add( new JButton( "West" ), BorderLayout.WEST );
card3.add( new JButton( "East" ), BorderLayout.EAST );
card3.add( new JButton( "South" ), BorderLayout.SOUTH );
card3.add( label3, BorderLayout.CENTER );
deck.add( card3, label3.getText() ); // add card to deck

// create and layout buttons that will control deck
JPanel buttons = new JPanel();
buttons.setLayout( new GridLayout( 2, 2 ) );
controls = new JButton[ names.length ];

for ( int count = 0; count < controls.length; count++ ) {
controls[ count ] = new JButton( names[ count ] );
controls[ count ].addActionListener( this );
buttons.add( controls[ count ] );
}

// add JPanel deck and JPanel buttons to the applet
container.add( buttons, BorderLayout.WEST );
container.add( deck, BorderLayout.EAST );

setSize( 450, 200 );
setVisible( true );

} // end constructor

// handle button events by switching cards
public void actionPerformed( ActionEvent event )
{
// show first card
if ( event.getSource() == controls[ 0 ] )
cardManager.first( deck );

// show next card
else if ( event.getSource() == controls[ 1 ] )
cardManager.next( deck );

// show previous card
else if ( event.getSource() == controls[ 2 ] )
cardManager.previous( deck );

// show last card
else if ( event.getSource() == controls[ 3 ] )
cardManager.last( deck );
}

// execute application
public static void main( String args[] )
{
CardDeck cardDeckDemo = new CardDeck();

cardDeckDemo.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE );
}

} // end class CardDeck

[xu_kewei]

你可以写事件处理动作。CardLayout有ActionEvent

[xu_kewei]

还有你可以使用Card的索引号

[jmfish]

前面程序我见过，调用next和previous，和当前card无关，不过还是谢谢。
请问楼上具体如何用索引号。

[ytdmm]

CardLayout类中没有此函数，并且也没有其他用于得到自身状态的方法。它的一些方法只用于设置当前显示的Card。

其实显示哪一个Card是由其他因素决定的，可以考虑一下利用其他的方法。例如添加三个按钮，单击一个按钮对应显示一个Card，则判断当前显示的哪一个Card只需判断哪个按钮被按下即可！