Java 8 – How to convert IntStream to Integer[]
How to convert IntStream to Integer array? The key is boxed() the IntStream into a Stream, then only convert to an Array.
Java 8 – Should we close the Stream after use?
Streams have a BaseStream.close() method and implement AutoCloseable, but nearly all stream instances do not actually need to be closed after use. Generally, only streams whose source is an IO…
Java 8 Stream – The peek() is not working with count()?
Many examples are using the .count() as the terminal operation for .peek(). However, for Java 9 and above, the peek() may print nothing. Since Java 9, if JDK compiler is…
Java 8 Stream – Convert List of List Strings to List Strings
As title, we can use flatMap to convert it. Similar to convert 2D array to 1D array using Stream.flatMap.
Java 8 Stream – Read a file line by line
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.
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…
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…
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…