java.lang.ArrayIndexOutOfBoundsException: 21 >= 21

Question

I got the below error message.

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)

on the third line of the below code.

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

I already added the 21st and 22nd column to the DefaultTableModel.

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];
            }

        });

But I don't know, what's the reason for showing ArrayIndexOutOfBounds exception.

Answer 1

Well you call JTable.removeColumn, each column of the array of columns is getting reindexed. For example, when element 0 is removed, the element that was at index 1 is now reindexed at index 0.

You need to remove those columns in reverse order, so that this reindexing doesn't happen:

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

You could also call 4 times the following line:

jTable.removeColumn(jTable.getColumnModel().getColumn(19));

since at each call i, column 19 + i will become column 19.