问java.lang.ArrayIndexOutOfBoundsException: 21 >= 21

EN

java.lang.ArrayIndexOutOfBoundsException: 21 >= 21
        at java.util.Vector.elementAt(Vector.java:427)
        at javax.swing.table.DefaultTableColumnModel.getColumn(DefaultTableColumnModel.java:277)
        at com.vanuston.medeil.uitables.PurchaseTable.createTable(PurchaseTable.java:182)
        at com.vanuston.medeil.ui.Purchase.applyDefaults$(Purchase.fx:130)

jTable.removeColumn(jTable.getColumnModel().getColumn(19));
jTable.removeColumn(jTable.getColumnModel().getColumn(20));
jTable.removeColumn(jTable.getColumnModel().getColumn(21));
jTable.removeColumn(jTable.getColumnModel().getColumn(22));

Vector cols = new Vector();
    Vector data = new Vector();
    int len = colName.length;
    System.out.println("col length " + len);
    for (int i = 0; i < initRow; i++) {
        Vector c = new Vector();
        for (int j = 0; j < len; j++) {
            if (j == 19 && j == 20) {
                c.addElement(Boolean.FALSE);
            } else {
                c.addElement(null);
            }
        }
        data.addElement(c);
    }
    for (int n = 0; n < len; n++) {
        cols.addElement(colName[n]);
        System.out.println(colName[n]);
    }
    try {
        jTable.setModel(new javax.swing.table.DefaultTableModel(data, cols) {

            Class[] type = types;
            boolean[] canEditCol = canEditCols;

            @Override
            public Class getColumnClass(int columnIndex) {
                return type[columnIndex];
            }

            @Override
            public boolean isCellEditable(int rowIndex, int columnIndex) {
                return canEditCol[columnIndex];
            }

        });