注释标注的代码的输出结果. import javax.swing.*; import java.awt.*; import java.awt.event.*; public class Win extends JFrame { JTextField textN1,textN2; JTextField showResult; JButton buttonAdd,buttonSub; Listener listen; public Win() { setLayout(new FlowLayout()); textN1 = new JTextField(8); textN2 = new JTextField(8); showResult = new JTextField(8); buttonAdd = new JButton("相加"); buttonSub = new JButton("相减"); listen = new Listener(); listen.se