Tem um jeito mais facil de fazer isso. Tipo usando um for com arrays?
jComboBox1.setSelectedItem("");
jComboBox2.setSelectedItem("");
jComboBox3.setSelectedItem("");
jComboBox4.setSelectedItem("");
jComboBox5.setSelectedItem("");
jComboBox6.setSelectedItem("");
jComboBox7.setSelectedItem("");
jComboBox8.setSelectedItem("");
jComboBox9.setSelectedItem("");
jComboBox10.setSelectedItem("");
jComboBox11.setSelectedItem("");
jComboBox12.setSelectedItem("");
jComboBox13.setSelectedItem("");
jComboBox14.setSelectedItem("");
jComboBox15.setSelectedItem("");
jComboBox16.setSelectedItem("");
jComboBox17.setSelectedItem("");
jComboBox18.setSelectedItem("");
jComboBox19.setSelectedItem("");
jComboBox20.setSelectedItem("");
jComboBox21.setSelectedItem("");
jComboBox22.setSelectedItem("");
jComboBox23.setSelectedItem("");
jComboBox24.setSelectedItem("");
jComboBox25.setSelectedItem("");
jComboBox26.setSelectedItem("");
jComboBox27.setSelectedItem("");
jComboBox28.setSelectedItem("");
jComboBox29.setSelectedItem("");
jComboBox30.setSelectedItem("");
jComboBox31.setSelectedItem("");
jComboBox32.setSelectedItem("");
jComboBox33.setSelectedItem("");
jComboBox34.setSelectedItem("");
jComboBox35.setSelectedItem("");
jComboBox36.setSelectedItem("");
jComboBox37.setSelectedItem("");
jComboBox38.setSelectedItem("");
jComboBox39.setSelectedItem("");
jComboBox40.setSelectedItem("");
jComboBox41.setSelectedItem("");
jComboBox42.setSelectedItem("");
jComboBox43.setSelectedItem("");
jComboBox44.setSelectedItem("");
jComboBox45.setSelectedItem("");
jComboBox46.setSelectedItem("");
jComboBox47.setSelectedItem("");
jComboBox48.setSelectedItem("");