This example demonstrates how to set the width of a column and prevent it from being resized by the user. 
    int rows = 3;
    int cols = 3;
    JTable table = new JTable(rows, cols);
    
    // Add data here
    
    // Lock the second column of the table to be 100 pixels wide
    int vColIndex = 1;
    int width = 100;
    TableColumn col = table.getColumnModel().getColumn(vColIndex);
    col.setMinWidth(width);
    col.setMaxWidth(width);
    col.setPreferredWidth(width);