运行登录程序就出现“Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException”错误

Question

做了个数字键盘式样的登录界面，只要在“editTf”输入密码，点击确定按钮激活"keyOk"命令就出现错误信息“Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException”
如下图，请有经验的智者帮忙指导下怎么解决这个问题。

    private void initComponents() {
        HmiSettings.m1Handler = new M1Handler(hmiSettings);

        //    The user is logged in
                    if(currentOnLineStat) {
                    if (HmiSettings.status.getLoggedOn()) {
                        
                            screenPanel.loginutil.exit();
                    } else {
                        setLogOff();
                    }
                    } else {

                        String strLogOn = HmiSettings.lngManager.getString("strings", "strLogOnCode");
                        LockDialog key = new LockDialog(hmiSettings.appFrame, strLogOn, "keyLogOn", true);
                        key.setShowLimits(false);
                        key.setShowOldValue(false);
                        key.setDotAllowed(false);
                        key.setMinusAllowed(false);
                        //key.setStringBackspace(hmiSettings.strBackspace);
                        //key.setStringCancel(hmiSettings.strCancel);
                        //key.setStringOk(hmiSettings.strOk);
                        //key.setStringOld(hmiSettings.strOld);
                        //key.setStringMin(hmiSettings.strMin);
                        //key.setStringMax(hmiSettings.strMax);
                        key.setEchoChar('*');
                        key.addLockListener(this);
                        key.setVisible(true); 
                        key.toFront();//将窗口至于前端
                    }
                    setPage("scrHome");//取消后，登录、退出系统无影响
                                
    
                
    }

    private void setPage(String page) {
    
        if(currentOnLineStat && !page.equals("scrHome")) {    // No returning home wanted after log on/off
            screenPanel.setPage(page);
        }
    }
    public void navigationCommand(String cmd) {
        setPage(cmd);
    }
    
    public void setLogOff(){
        if(HmiSettings.status.getLoggedOn()) {
            HmiSettings.status.setLoggedOn(false);
            screenPanel.setLogOn(false);
        }
    }

    public void setLogOn() {
        if (!HmiSettings.status.getLoggedOn()) {
            HmiSettings.status.setLoggedOn(true);
                        screenPanel.setLogOn(true);
        }
    }


    public void lockNewValue(LockEvent evt) {
        String name = evt.getName();        
        if(name.equals("keyLogOn")) 
            if(hmiSettings.keyPadCode.equals(evt.getString())) {
                HmiSettings.status.setLoggedOn(true);
**351行：**                screenPanel.setLogOn(HmiSettings.status.getLoggedOn());
            }
        
    }

if(cmd.equals("keyOk")) {
            boolean valOk = false;
            String sVal = editTf.getText();
            double dVal = 0.0;
            int iVal = 0;
            
            try {
                dVal = Double.valueOf(sVal).doubleValue();
                iVal = Integer.valueOf(sVal).intValue();
            }
            catch (NumberFormatException e) {
                
            }
            
            if(useLimits) {
                if(isInteger) {
                    if((iVal >= iMinValue) && (iVal <= iMaxValue)) {
                        valOk = true;
                    }
                }
                else {
                    if((dVal >= dMinValue) && (dVal <= dMaxValue)) {
                        valOk = true;
                    }
                }
            } else {
                valOk = true;
            }
            if(valOk)
                if((sVal.equals("00000")) && (sVal != null && !"".equals(sVal))) {//sVal.equals("64826"),sVal.equals(hmiSettings.keyPadCode.equals("64826"))
**541行：**                  sendNewValue(dVal, iVal, sVal);
                  JOptionPane.showMessageDialog(null, "密码正确！");
                  dispose();//关闭当前窗口
            } else if(sVal.equals("")){//if (new String(editTf.getText()).trim().equals(""))sVal.equals("")
                  JOptionPane.showMessageDialog(null, "未填写密码！");
            }
              else
            {
                  JOptionPane.showMessageDialog(null, "密码错误！");
                  editTf.setText("");
            }    
        }

private void sendNewValue(double dVal, int iVal, String sVal) {
        if(!listeners.isEmpty()) {
            LockEvent val = new LockEvent(this, dVal, iVal, sVal, name);
            for(int i = 0; i < listeners.size(); i++) {
                LockListener listener = (LockListener) listeners.elementAt(i);
**601行：**                listener.lockNewValue(val);
            }
        }
    }

import java.util.EventObject;

public class LockEvent extends EventObject {

    private double dValue;
    private int iValue;
    private String sValue;
    private String name;
    
    public LockEvent(Object source, double v, int i, String s, String n) {
        super(source);
        dValue = v;
        iValue = i;
        sValue = s;
        name = n;
    }
    
    public double getDouble() {
        return dValue;
    }
    public int getInt() {
        return iValue;
    }
    public String getString() {
        return sValue;
    }
    public String getName() {
        return name;
    }
}

Answer 1

 String name = evt.getName(); 
打印一下name是不是null值。
或者是密码控件定义成私有变量了。