Q:

Why does Java BigDecimal return 1E+1?

Why does this code sometimes return 1E+1 whilst for other inputs (e.g. 17) the output is not printed in scientific notation?
BigDecimal bigDecimal = BigDecimal.valueOf(doubleValue).multiply(BigDecimal.valueOf(100d)).stripTrailingZeros();
System.out.println("value: " + bigDecimal);

A:

use bigDecimal.toPlainString():
 BigDecimal bigDecimal = BigDecimal.valueOf(100000.0)
                     .multiply(BigDecimal.valueOf(100d))
                     .stripTrailingZeros();
 System.out.println("plain      : " + bigDecimal.toPlainString());
 System.out.println("scientific : " + bigDecimal.toEngineeringString());

outputs:

plain      : 10000000
scientific : 10E+6

A:

It's the implicit .toString() conversion that is happening when you pass the result into System.out.println().

A:

The exact rationale for the behaviour of BigDecimal.toString() is explained in the API doc in great (and near incomprehensible) detail.
To get a consistent (and locale-sensitive) textual representation, you should use DecimalFormat.

