Java 8 Stream – Read a file line by line
by In Java 8, you can use Files.lines to read file as Stream. A new method lines() has been added since 1.8, it lets BufferedReader returns content as Stream.
Month: May 2022
Java – Convert String to double
In Java, we can use Double.parseDouble() to convert a String to primitive double, and we can use Double.valueOf() to convert a String to an Double object.
How to format a double in Java
In Java, we can use String.format or DecimalFormat to format a double, both support Locale based formatting.
Java – How to round double / float value to 2 decimal places
There are a few ways to round float or double to 2 decimal places in Java. In short, for monetary calculation, picks BigDecimal; for display purpose, picks DecimalFormat(“0.00”). We can use DecimalFormat(“0.00”) to ensure the number always round to 2 decimal places. For DecimalFormat, the default rounding mode is RoundingMode.HALF_EVEN, and we can use setRoundingMode(RoundingMode) to set a specified rounding mode. We also can convert the double to a BigDecimal object and set the scale and rounding mode. The String.format is working fine, and the default rounding is half-up; however, we have no way to configure the type of rounding mode.
Java – Display double in 2 decimal places
In Java, there are few ways to display double in 2 decimal places. We can use DecimalFormat(“0.00”) to ensure the number is round to 2 decimal places. We also can use String formater %2f to round the double to 2 decimal places. However, we can’t configure the rounding mode in String.format, always rounding half-up. We can convert double value to BigDecimal to set scale to 2 decimal places.
How to calculate monetary values in Java
There are many monetary values calculation in the financial or e-commerce application, and there is one question that arises for this – Should we use double or float data type to represent the monetary values? Answer: Always uses java.math.BigDecimal to represent the monetary values. With double or float – It cannot calculate all the decimals precisely. To avoid the decimal issue above, we can use BigDecimal to represent the monetary values; furthermore, we can control the BigDecimal scale much more straightforward. BigDecimal performs exact decimal arithmetic.
Java 8 – How to Sum BigDecimal using Stream?
In Java 8, we can use the Stream.reduce() to sum a list of BigDecimal. Java example to sum a list of BigDecimal values, using a normal for loop and a stream.reduce(). We can use technique of Map and Reduce to Sum all BigDecimal from a list of Invoices.
Java 8 Stream findFirst() and findAny()
In Java 8 Stream, the findFirst() returns the first element from a Stream, while findAny() returns any element from a Stream.
Java – How to convert a primitive Array to List
Code snippets to convert a primitive array int[] to a List
How to sort an Array in java
Java example to show the use of Arrays.sort() to sort an Array. The code should be self-explanatory. Output Download Source Code $ git clone https://github.com/favtuts/java-core-tutorials-examples $ cd …