AtomicInteger class” understanding and use
First look at the two paragraph of code, one is Integer, and the other is AtomicInteger.
public class Sample1 {
private static Integer count = 0;
synchronized public static void increment() {
count++;
}
}
The following is AtomicInteger’s:
public class Sample2 {
private static AtomicInteger count = new AtomicInteger(0);
public static void increment() {
count.getAndIncrement();
}
}
When using Integer, you must add synchronized to ensure that no concurrent threads are accessed at the same ti...
Introduction to BroadcastReceiver
BroadcastReceiverIs one of the four components to complete communication between components or applications.
Broadcast: Radio broadcast
BroadcastReceiver: Broadcast receivers
A radio and broadcast receiver completes a message mechanism at the weight level because it needs to activate the component.
Two attention
Every time a broadcast message arrives in Android, an instance of BroadcastReceiver is created and the onReceive () method is executed
onReceive()After execution of the method, the instance of BroadcastReceiver will be destroyed.
onReceive()Method ...
Title Description
There is a checkerboard for M * N, some of which are obstacles. Now you have to choose some grid to place some soldiers, a grid can place up to one soldier, obstacle grid can not place soldiers. We call these soldiers occupying the whole chessboard. When they meet the requirements of line I, at least Li soldiers are placed, column J.At least Cj soldiers were placed. Now your task is to require the use of a minimum number of soldiers to occupy the whole chessboard.
Input output format
Input format:
The first row, the two numbers M, N and K, respectively indicate the number...
Method 1:
distinct
select count(distinct CName) from Course
Method two:
Using grouping group by
select count(1) from Course group by CName
Topic gate
The main idea of the topic is:
Given n n n n 01 strings, let you construct a string so that the strings and the similarity between these strings as low as possible. If the two strings correspond to the same position, the similarity degree is increased by one.
Ideas:
You can get any 01 strings after changing each part of the 01 string. I want all strings to end up in the same 01 string. We will change the meaning of the question to make the highest degree of similarity as low as possible, that is, to make the lowest degree of dissimilarity as high as possible, and each 01 string cha...
Paper:Working hard to know your neighbor’s margins: Local descriptor learning loss
Why to introduce this article: This 2018cvpr article is mainly from the difficult sample, proposed a loss, simple but effective, in image matching, retrieval, Wide Baseline stereo, and so on have doneExtensive detailed experiments，In real tasksrealThe result of state-of-the-art is obtained. Code: https://github.com/DagnyT/hardnet. The papers in the last blog can be combined with this, and it will be better to read together. In addition, these are obtained through learn.Descriptor is not popular in practic...
1. The power supply socket of the oscilloscope must be a tripod socket, and it must be grounded reliably. In the absence of grounding wire, the power supply plug of the oscilloscope should pay attention to dividing the zero line and the fire line when it is connected, and the probe grounding wire of the oscilloscope should not be charged at one end.
Two, when testing the signal on the line, it is necessary to connect the ground wire probe before measuring the information. Because without first addressing, the probe may be electrified and damage the test element.
