我想取列中所有数值的平均值，并用计算出的平均值更新该列中的空单元格，但是在更新空单元格期间遇到问题...请给我建议...以下是我的代码。 ..
/*---------------- Function to apply Mean Imputation Algorithm on saved data in Database -----------------*/
public void CalcMean(String tableName) {
Statement stmt = null;
String sql = null;
ResultSet rs = null;
try {
setConnection();
//connection.setAutoCommit(false);
stmt = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
sql = "SELECT * FROM " + tableName;
System.out.println("sql :" + sql);
rs = stmt.executeQuery(sql);
CachedRowSet rowset = new CachedRowSetImpl();
rowset.populate(rs);
while(rowset.next()){
ResultSetMetaData rsmd = rowset.getMetaData();
int numOfCols = rsmd.getColumnCount();//get total number of columns from database
for(int i = 1; i <= numOfCols; i++){
if (rowset.getString(i)== null || rowset.getString(i).equals("*") || rowset.getString(i).equals("?"))
{
System.out.println("was NULL"+i);// Database contains NULL
String nullCellValue = rowset.getString(i);// get the designated cell's value
System.out.println(nullCellValue);
}
else
{
System.out.println("not NULL"+i);// Database does not contain NULL
String cellValue = rowset.getString(i);// get the designated cell's value
System.out.println(cellValue);
/*----- check if the value in cell is Numerical or Categorical [0-9]+-----*/
String regex = "[0-9.]+";
if(cellValue.matches(regex)){
System.out.println("Value is numerical");
String colName = rsmd.getColumnName(i);
System.out.println(colName);
CalcNumericValMean(colName , tableName);
}
else{
System.out.println("Value is categorical");
}
}
}
}
//Clean-up environment
rs.close();
stmt.close();
//connection.commit();
closeConnection();
}/*catch (SQLException ex) {
try {
connection.rollback();
System.out.println("RollBack performed");
closeConnection();
} catch (Exception e1) {
System.out.println("RollBack failed");
}
} */
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// Function to Calculate Mean of Numeric Values
public void CalcNumericValMean(String colName , String tableName){
Statement st = null;
String sql = null;
String average = null;
try{
setConnection();
//connection.setAutoCommit(false);
st = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
sql = "SELECT AVG( " + colName + " ) FROM " + tableName;
System.out.println("sql :" + sql);
ResultSet rset = st.executeQuery(sql);
CachedRowSet rowset = new CachedRowSetImpl();
rowset.populate(rset);
int i = 1;
while(rowset.next()) { // check if a result was returned
average = rowset.getString(i); // get your result
System.out.println("average is : " + average);
i++;
}
//Clean-up environment
rset.close();
st.close();
//connection.commit();
closeConnection();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
最佳答案
也许你应该尝试使用表模型来实现？ 。表模型覆盖包含 public void setValueAt(Object value, int row, int col) ，您可以对其进行 ovveride 并在表的特定列上进行数学计算
关于java - 如何使用该列中数值的平均值更新特定列的空单元格？ (Mysql使用java)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34379714/