一个 JAVA 的考试系统，如何实现上一题，和下一题两个按钮

[amazingK]

switch (ac) { case "下一题": n++; if (n>20) { JOptionPane.showMessageDialog(null, "您已答题完毕请交卷", "信息反馈", JOptionPane.YES_NO_CANCEL_OPTION); n--; } lblNewLabel.setText("第"+n+"题："); if (n<=10) { qBank=qDao.getquestions(list.get(n-1)); textPane.setText(qBank.getQcontent()); QA.setText("A."+qBank.getQA()); QB.setText("B."+qBank.getQB()); }else { qBank=qDao.getquestions(list.get(n-1)); textPane.setText(qBank.getQcontent()); QA.setText("A."+qBank.getQA()); QB.setText("B."+qBank.getQB()); QC.setVisible(true); QD.setVisible(true); QC.setText("C."+qBank.getQC()); QD.setText("D."+qBank.getQD()); }

			break ；

这是实现下一题的按钮设置，上一题的按钮代码怎么写

[814084764]

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[xuhaoyangx]

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