現在沒有編譯錯誤,該值不會顯示,只有消息「number:」 我已經在這裏,除了它之前顯示「number:NULL」之前的例外,但我想我到了那裏......謝謝大家。我一直在讀線程了大約一個星期,但我學到了更多今晚你建議無法找到符號錯誤,空指針
登錄類
public class Login_JPanel extends JPanel
{
JLabel welcomeMessage,
mainPicture;
JButton playerregistrationJB = new JButton ("Player Registration");
JLabel userAccountNumberJLabel = new JLabel("<HTML><CENTER><FONT SIZE=6
COLOR=YELLOW>Please, enter your account number below and then click on player
registration to continue </COLOR></CENTER></HTML>");
JTextField useraccountnumberJTF = new JTextField();
public Login_JPanel()
{
//========================================================
//SET UP USERNAME JLABEL AND TEXT FIELD
//========================================================
add(userAccountNumberJLabel);
userAccountNumberJLabel.setBounds(322, 335, 300, 155);
add(useraccountnumberJTF);
useraccountnumberJTF.setBounds (330, 500, 90, 25);
playerregistrationJB.setBounds(350, 600, 325, 75);
playerregistrationJB.setFont(new Font("Broadway", Font.BOLD, 30));
playerregistrationJB.setForeground(Color.red);
playerregistrationJB.setBackground(Color.YELLOW);
add(playerregistrationJB);
add(welcomeMessage = new JLabel("Welcome!!"));
welcomeMessage.setBounds(0,0,50,23);
add(mainPicture = new JLabel(new ImageIcon("henkidama.jpg")));
mainPicture.setBounds(0,0,50,50);
setLayout(null);
setBounds(0,0,1000,800);
}
}
這是playerregistration面板
public class PlayerRegistration_JPanel extends JPanel
{
Login_JPanel loginJP = new Login_JPanel();
JLabel welcomeMessage,
mainPicture;
JLabel useraccountnumberJL = new JLabel();
JButton submitJB = new JButton ("Submit");
public PlayerRegistration_JPanel()
{
add(useraccountnumberJL);
useraccountnumberJL.setText("number: " +
loginJP.useraccountnumberJTF.getText());
useraccountnumberJL.setBounds(100, 75, 625, 200);
useraccountnumberJL.setFont(new Font("Broadway", Font.BOLD, 18));
submitJB.setBounds(350, 600, 325, 75);
submitJB.setFont(new Font("Broadway", Font.BOLD, 30));
submitJB.setForeground(Color.red);
submitJB.setBackground(Color.YELLOW);
add(submitJB);
add(welcomeMessage = new JLabel("Welcome to Building Another Panel!!"));
welcomeMessage.setBounds(0,0,50,23);
add(mainPicture = new JLabel(new ImageIcon("henkidama.jpg")));
mainPicture.setBounds(0,0,50,50);
setLayout(null);
setBounds(0,0,1000,800);
}
}
有一個JLabel
要求用戶輸入一個號碼,直到這一點一個String
,那麼用戶應該點擊playerregistrationJB
,號碼出現在PlayerRegistration_JPanel
。 此外,還有一個ProccessedJPanel
,我撥打我的所有按鈕ActionListener
, 也finalJpanel
我在哪裏我的主要在一個框架。我不知道問題在哪裏,因爲我的JTextField
是全球性的(儘管我們沒有像Java中的GLOBAL VARIABLE這樣的東西)。
請注意編輯並指出我,如果我錯了某處!此外,你剛剛在你的'PlayerRegistration_JPanel'中初始化你的'Login_JPanel'類的對象來訪問'useraccountnumberJTF.getText()',像'Login_JPanel loginPanel = new Login_JPanel(); loginPanel.useraccountnumberJTF.getText();'? – 2012-04-27 05:40:04
只需在你的'Login_JPanel'類裏面聲明'JTextField'像這樣'public static JTextField useraccountnumberJTF = new JTextField();'現在在你的'PlayerRegistration_JPanel'類裏面就像這樣'Login_JPanel.useraccountnumberJTF.getText()'來訪問它。這將做:-) – 2012-04-27 13:08:56