private void tsbAddStudent_Click(object sender, EventArgs e) { if (objFrmAddStudent == null) { objFrmAddStudent = new FrmAddStudent(); objFrmAddStudent.Show();//show this windows } else { objFrmAddStudent.Activate(); objFrmAddStudent.WindowState = FormWindowState.Normal; } }
//怎样保证对象的唯一性 private void tsmiAddStudent_Click(object sender, EventArgs e) { if (objFrmAddStudent == null) { objFrmAddStudent = new FrmAddStudent(); objFrmAddStudent.Show(); } else { objFrmAddStudent.Activate();//激活只能在最小化的时候起作用 objFrmAddStudent.WindowState = FormWindowState.Normal; } }