文本框限制

文本框里，只能输入0到9的数字 ，至少输入一个值，不能为空

package  com.swtdesigner; import  org.eclipse.jface.dialogs.MessageDialog; import  org.eclipse.swt.SWT; import  org.eclipse.swt.events.SelectionAdapter; import  org.eclipse.swt.events.SelectionEvent; import  org.eclipse.swt.events.VerifyEvent; import  org.eclipse.swt.events.VerifyListener; import  org.eclipse.swt.widgets.Button; import  org.eclipse.swt.widgets.Display; import  org.eclipse.swt.widgets.Shell; import  org.eclipse.swt.widgets.Text; public   class  HelloWorldGong ... {    private static Text text;    /** *//**     * Launch the application     * @param args     */    public static void main(String[] args)    ...{        final Display display = Display.getDefault();        final Shell shell = new Shell();        shell.setSize(500, 375);        shell.setText("你好世界");        //        shell.open();        text = new Text(shell, SWT.BORDER);        text.addVerifyListener(new VerifyListener() ...{            public void verifyText(VerifyEvent e)            ...{                boolean b=("0123456789".indexOf(e.text) >= 0);                 e.doit=b;            }        });        text.setTextLimit(10);        text.setBounds(56, 64, 80, 25);        final Button button = new Button(shell, SWT.NONE);        button.addSelectionListener(new SelectionAdapter() ...{            public void widgetSelected(SelectionEvent e)            ...{                String str=text.getText();                if(str==null||str.equals(""))                    MessageDialog.openWarning(shell, "警告", "请输入一个字符");                else                    MessageDialog.openInformation(shell, "信息提示", "请输入值通过验证");            }        });        button.setText("确定");        button.setBounds(56, 125, 48, 22);                        shell.layout();        while (!shell.isDisposed())        ...{            if (!display.readAndDispatch())                display.sleep();        }    }}