Converting from Integer, to BigInteger
The method you want is BigInteger#valueOf(long val). E.g., Making a String first is unnecessary and undesired.
java
How to get today’s Date?
Since the methods are deprecated, you can do this with Calendar: And if you need a Date object in the end, simply call today.getTime()
How to override toString() properly in Java?
The toString is supposed to return a String. I suggest you make use of your IDE’s features to generate the toString method. Don’t hand-code it. For instance, Eclipse can do so if you simply right-click on the source code and select Source > Generate toString
How to create a directory in Java?
After ~7 year, I will update it to better approach which is suggested by Bozho.
java – how to create and manipulate a bit array with length of 10 million bits
Use BitSet (as Hunter McMillen already pointed out in a comment). You can easily get and set bits. To iterate just use a normal for loop.
How to check if a String is numeric in Java
With Apache Commons Lang 3.5 and above: NumberUtils.isCreatable or StringUtils.isNumeric. With Apache Commons Lang 3.4 and below: NumberUtils.isNumber or StringUtils.isNumeric. You can also use StringUtils.isNumericSpace which returns true for empty strings and ignores internal spaces in the string. Another way is to use NumberUtils.isParsable which basically checks the number is parsable according to Java. (The … Read more
This Activity already has an action bar supplied by the window decor?
I am making an Android app using Toolbar with Custom style but when i’m running the app, i’m getting the following error: Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead. Styles.xml … Read more
java.lang.NumberFormatException: empty String
You should check your field before parse double:
Using Math.round to round to one decimal place?
I have these two variables Then I did this expression but I end up with 27.0. In fact I have many other variables and when I use them in the expression I always get a 0 in the tenth’s place.
JOptionPane YES NO OPTION
You should actually take the result from the option pane: Otherwise, it remains set to JOptionPane.YES_NO_OPTION. Cleaner would be: Although, I’m not sure what this line is expected to do in the posted code: remove(dialogButton);. For more details and examples check out How to Make Dialogs tutorial.