Question

如何输入小数或双数？我想如果我输入.56它会在数据库中保存为.56而不是1，因为它的四舍五入并且我想忽略舍入...

这是servlet，我有豆子，它也设置为加倍;我也尝试过DecimalFormat，但仍然没有工作，或者我只是不知道如何使用它。

neutrophils = rs.getInt("neutrophils");
monocytes = rs.getInt("monocytes");
eosinophils = rs.getInt("eosinophils");
basophils = rs.getInt("basophils");
lymphocytes = rs.getInt("lymphocytes");

total= (neutrophils + monocytes + eosinophils + eosinophils + basophils + lymphocytes);

我这样做，我将datatype的值更改为VARCHAR，但错误是java.lang.NullPointerException;那是为什么？

neutrophils = Double.parseDouble(rs.getString("neutrophils"));
monocytes = Double.parseDouble(rs.getString("monocytes"));
eosinophils = Double.parseDouble(rs.getString("eosinophils"));
basophils = Double.parseDouble(rs.getString("basophils"));
lymphocytes = Double.parseDouble(rs.getString("lymphocytes"));
bands = (neutrophils + monocytes + eosinophils + eosinophils + basophils + lymphocytes);

Answer 1

如果rs为ResultSet，您只需使用rs.getDouble。如果由于某种原因您不想使用它，请将结果作为String获取，然后转换

Double.parseDouble(rs.getString(ColumnLabel));

在JAVA中输入小数或双数

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