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Java null check why use == instead of .equals()
...a null reference, you'll get a NullPointerException.
For instance:
class Foo {
private int data;
Foo(int d) {
this.data = d;
}
@Override
public boolean equals(Object other) {
if (other == null || other.getClass() != this.getClass()) {
return false;
...
gitignore all files of extension in directory
...**" followed by a slash means match in all directories. For
example, "**/foo" matches file or directory "foo" anywhere, the same
as pattern "foo". "**/foo/bar" matches file or directory "bar"
anywhere that is directly under directory "foo".
A trailing "/**" matches everything inside. For exa...
How can one see the structure of a table in SQLite? [duplicate]
... If you want to get the table info for an attached database 'foo', you run PRAGMA foo.table_info(table_name);
– paddy
May 1 '17 at 5:49
...
PHP Multidimensional Array Searching (Find key by specific value)
... return $found;
}
}
// Example:
$data = array(
array('foo' => 'test4', 'bar' => 'baz'),
array('foo' => 'test', 'bar' => 'baz'),
array('foo' => 'test1', 'bar' => 'baz3'),
array('foo' => 'test', 'bar' => 'baz'),
array('foo' => 'test', ...
Why do we usually use || over |? What is the difference?
...ing would be to consider the following example.
Boolean b = true;
if(b || foo.timeConsumingCall())
{
//we entered without calling timeConsumingCall()
}
Another benefit, as Jeremy and Peter mentioned, for short-circuiting is the null reference check:
if(string != null && string.isEmpt...
Compare object instances for equality by their attributes
I have a class MyClass , which contains two member variables foo and bar :
15 Answers
...
What are type lambdas in Scala and what are their benefits?
...ist at value level.
The following example might help:
// VALUE LEVEL
// foo has signature: (String, String) => String
scala> def foo(x: String, y: String): String = x + " " + y
foo: (x: String, y: String)String
// world wants a parameter of type String => String
scala> def world(...
How can I exclude one word with grep?
...ape the !):
grep -P '(?!.*unwanted_word)keyword' file
Demo:
$ cat file
foo1
foo2
foo3
foo4
bar
baz
Let us now list all foo except foo3
$ grep -P '(?!.*foo3)foo' file
foo1
foo2
foo4
$
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...
What is the equivalent of the C# 'var' keyword in Java?
...s are still 100% statically typed. This will not compile:
var myString = "foo";
myString = 3;
var is also useful when the type is obvious from context. For example:
var currentUser = User.GetCurrent();
I can say that in any code that I am responsible for, currentUser has a User or derived class...
Why doesn't 'ref' and 'out' support polymorphism?
...t be able to assign value to ref/out parameter.
If you try to pass b into Foo2 method as reference, and in Foo2 you try to assing a = new A(), this would be invalid.
Same reason you can't write:
B b = new A();
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