Adding multiple BigInteger values to an ArrayList
This question already has an answer here:
I'm not really sure what you're after. You have four alternatives:
1. Add items individually
Instantiate a concrete List type and then call add() for each item:
List<BigInteger> list = new ArrayList<BigInteger>();
list.add(new BigInteger("12345"));
list.add(new BigInteger("23456"));
2. Subclass a concrete List type (double brace initialization)
Some might suggest double brace initialization like this:
List<BigInteger> list = new ArrayList<BigInteger>() {{
add(new BigInteger("12345"));
add(new BigInteger("23456"));
}};
I recommend not doing this. What you're actually doing here is subclassing ArrayList , which (imho) is not a good idea. That sort of thing can break Comparator s, equals() methods and so on.
3. Using Arrays.asList()
Another approach:
List<BigInteger> list = new ArrayList<BigInteger>(Arrays.asList(
new BigInteger("12345"),
new BigInteger("23456")
));
or, if you don't need an ArrayList , simply as:
List<BigInteger> list = Arrays.asList(
new BigInteger("12345"),
new BigInteger("23456")
);
I prefer one of the above two methods.
4. Collection literals (Java 7+)
Assuming Collection literals go ahead in Java 7, you will be able to do this:
List<BigInteger> list = [new BigInteger("12345"), new BigInteger("23456")];
As it currently stands, I don't believe this feature has been confirmed yet.
That's it. Those are your choices. Pick one.
BigIntegerArrays.asList(1, 2, 3, 4);
Where BigIntegerArrays is a custom class which does what you need it to do. This helps if you are doing this often. No rocket science here - ArrayList BigIntegerArrays.asList(Integer... args) will use a FOR loop.
Arrays.asList(new BigInteger("1"), new BigInteger("2"), new BigInteger("3"), new BigInteger("4"));
您可能可以创建一个方法，该方法返回给定一个String的新BigInteger，称之为bi（..）以减小该行的大小。
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