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 ButtonTest {
    private static Text text;
    public static void main(String[] args) {
        final Display display = Display.getDefault();
        final Shell shell = new Shell();
        shell.setSize(500, 375);
        shell.setText("SWT Application");
        shell.open();

        final Button okButton = new Button(shell, SWT.NONE);
        okButton.setImage([color=FF0000]SWTResourceManager[/color].getImage(ButtonTest.class, "275.jpg"));
        okButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                String str = text.getText();
                if (str == null || str.equals("")) {
                    MessageDialog.openInformation(shell, "", "please enter a number");
                } else {
                    MessageDialog.openInformation(shell, "", "your enter the number is true");
                }
            }
        });
        okButton.setText("OK.");
        okButton.setBounds(81, 183, 244, 54);

        text = new Text(shell, SWT.BORDER);
        text.setTextLimit(10);  //最都只能输入10个字符
        text.setBounds(70, 85, 228, 46);
        text.addVerifyListener(new VerifyListener(){//检查监听器,每输入一个字符都回触发
            public void verifyText(VerifyEvent e) {
                //检查输入字符(e.text)是否在0123456789这个字符串中,不在indexOf会返回-1
                boolean b = "0123456789".indexOf(e.text) >= 0 ;
                e.doit = b;  //doit属性如果为true,则字符允许输入,反之不允许
            }
        });

        shell.layout();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
    }
}


eclipse编辑的时候，红色部分报错，不能处理它，怎么回事哦？求助～ 这个是不是一个类？要导入什么包呢？