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How do I make the method return type generic?
... define callFriend this way:
public <T extends Animal> T callFriend(String name, Class<T> type) {
return type.cast(friends.get(name));
}
Then call it as such:
jerry.callFriend("spike", Dog.class).bark();
jerry.callFriend("quacker", Duck.class).quack();
This code has the benefit...
What is a NullReferenceException, and how do I fix it?
...ess members (such as methods) through a null reference. The simplest case:
string foo = null;
foo.ToUpper();
This will throw a NullReferenceException at the second line because you can't call the instance method ToUpper() on a string reference pointing to null.
Debugging
How do you find the source ...
Process.start: how to get the output?
...ead from it:
proc.Start();
while (!proc.StandardOutput.EndOfStream)
{
string line = proc.StandardOutput.ReadLine();
// do something with line
}
You can use int.Parse() or int.TryParse() to convert the strings to numeric values. You may have to do some string manipulation first if there ar...
ES6 class variable alternatives
...bles in ESNext, check this example:
class Foo {
bar = 2
static iha = 'string'
}
const foo = new Foo();
console.log(foo.bar, foo.iha, Foo.bar, Foo.iha);
// 2, undefined, undefined, 'string'
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How to insert a SQLite record with a datetime set to 'now' in Android application?
...ravitamada', 'datetime()'");
Method 3
Using java Date functions
private String getDateTime() {
SimpleDateFormat dateFormat = new SimpleDateFormat(
"yyyy-MM-dd HH:mm:ss", Locale.getDefault());
Date date = new Date();
return dateFormat.format(date);
}
Conten...
Get number of digits with JavaScript
...n't need parenthesis ():
function getlength(number) {
return number.toString().length;
}
UPDATE: As discussed in the comments, the above example won't work for float numbers. To make it working we can either get rid of a period with String(number).replace('.', '').length, or count the digits ...
How do you round to 1 decimal place in Javascript?
...nded.toFixed(1)
// fixed is always to 1 d.p.
// NOTE: .toFixed() returns a string!
// To convert back to number format
parseFloat(number.toFixed(2))
// 12.34
// but that will not retain any trailing zeros
// So, just make sure it is the last step before output,
// and use a number format during ca...
MySQL search and replace some text in a field
...REPLACE(field, 'foo', 'bar') WHERE INSTR(field, 'foo') > 0;
REPLACE (string functions)
INSTR (string functions)
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Awk学习笔记 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...候。格式如下：
sub (regular expression, substitution string):
sub (regular expression, substitution string, target string)
实例：
$ awk '{ sub(/test/, "mytest"); print }' testfile
$ awk '{ sub(/test/, "mytest"); $1}; print }' testf...
How to quickly and conveniently create a one element arraylist [duplicate]
...onstruct an ArrayList and the fixed-sizeList like
return new ArrayList<String>(Arrays.asList(s));
and (in Java 7+) you can use the diamond operator <> to make it
return new ArrayList<>(Arrays.asList(s));
Single Element List
Collections can return a list with a single elemen...