我有一个数字样本.我将它们存储在List带有时间戳和值的数据点中.这是我的代码:
List<Number> samples = {55,67,57,67};
List<Number[]> dps = Lists.newArrayList();
Calender c1; c1.set(2013, 5, 20, 15, 44, 00);
int timeStartSec = (int) (c1.getTime().getTime() / 1000);
for(Number num: samples){
dps.add(new Number[] { timeStartSec, num});
timeStartSec = timeStartSec+5;
}
System.out.println("Final DataPoints " + dps);
输出:
Final DataPoints [[Ljava.lang.Number;@af8358, [Ljava.lang.Number;@d80be3, [Ljava.lang.Number;@1f4689e, [Ljava.lang.Number;@1006d75, [Ljava.lang.Number;@1125127, [Ljava.lang.Number;@18dfef8, [Ljava.lang.Number;@15e83f9, [Ljava.lang.Number;@2a5330, [Ljava.lang.Number;@bb7465,]
为什么打印java.lang.Number而不是适当的值？
是否有在静态方法中引用自己的类的简写？
说我有这段代码:
class SuperLongClassName(object):
@staticmethod
def sayHi():
print 'Hi'
@staticmethod
def speak():
SuperLongClassName.sayHi() # Is there a shorthand?
我正在练习渲染和绘制图形,我似乎无法找出为什么eclipse在1/5左右给我一个错误.
Exception in thread "Thread-3" java.lang.NullPointerException
at game.StartingPoint.run(StartingPoint.java:74)
at java.lang.Thread.run(Unknown Source)
这是我的线程的问题吗？我怎样才能解决这个问题？
这是我的源代码.
StartingPoint.java:
package game;
import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
public class StartingPoint extends Applet implements Runnable {
Image i;
Graphics doubleG;
Ball b1;
Ball b2;
public StartingPoint() {
}
@Override
public void init() {
}
@Override
public void start() {
setSize(480, 360);
Thread thread = new Thread(this);
thread.start();
b1 = new Ball(40, 40);
b2 = new Ball(70, 200);
}
@Override
public void stop() { …我将椭圆作为拟合数据集的水平曲线.选择一个特定的椭圆后,我想将其报告为中心点,半长轴和短轴长度以及旋转角度.换句话说,我想从形式转换(使用mathematica)我的椭圆方程:
Ax^2 + By^2 + Cx + Dy + Exy + F = 0
更标准的形式:
((xCos[alpha] - ySin[alpha] - h)^2)/(r^2) + ((xSin[alpha] + yCos[alpha] - k)^2)/(s^2) = 1
(h,k)中心在哪里,alpha是旋转角度,r并且s是半轴
我试图转换的实际等式是
1.68052 x - 9.83173 x^2 + 4.89519 y - 1.19133 x y - 9.70891 y^2 + 6.09234 = 0
我知道中心点是拟合的最大值,即:
{0.0704526, 0.247775}
def CostFunction(A):
return sum(A)
A = [[1,1,1],[2,2,2]]
print CostFunction(A[0:])
答案应该是3,但应该有一些问题A.
我正在使用一个开关来计算两个数字,但是当我尝试做任何类型的运算符时我只是继续得到0.
//imports
import java.util.Scanner;
public class Calculator {
public static void main (String[] args) {
//get first number
Scanner scan = new Scanner(System.in);
System.out.println("Please enter the first number: > ");
int num1 = scan.nextInt();
// get second number
System.out.println("Please enter the second number: > ");
int num2 = scan.nextInt();
// what the user wants to do
System.out.println("Please enter the method you would like to use "
+ "(+ , - , * , / , ^ ) > …我试图从列表中找到大于某个值的值(在我的例子中已知).
例:
特定
list = [1, 2, 5, 10, 15]; //list is sorted
查找大于X(=7在本例中)的值.
期望的结果=返回值为的列表= [10, 15]
我尝试使用java二进制搜索,就像
int index = Collections.binarySearch(list, X);
我的计划是找到索引(of X)然后返回索引后的所有元素.
但索引返回否定,我明白因为7不在列表中.
还有其他方法吗？有人请建议.
我有一个变量说private int minutes = 00.
如果我这样做System.out.println(minutes),Java将打印0而不是00,这是值.它正在删除最后的零,但在这个特定的例子中,我希望它打印00.怎么做？
我也尝试将分钟作为一个字符串,然后执行:Integer.parseInt(minutes)然后打印出来.但结果是一样的.
我的python 2.7代码有问题,似乎无法从朋友那里找到任何答案,所以我来到这里.我是python和编程的完整菜鸟.这是代码:
import time
import random
a = ['Spooky','Sexy','Snazzy','Random','Wild','Smoggy','Enchanting','Quick','Acoustic','Irritating','Annoying','Thirsty','Fierce','Embarassed','Touch']
b = ['Kurtis','Tisa','Randy','Theda','Dani','Beulah','Dallas','Jeannette','Vera','Kristopher','Donna','Wanda','Sergio','Betsy','Holly']
c = ['1873','123','448','8781','1284','3','45','34']
d = ['Hicks','Ryan','Houston','Cunningham','Ortiz','Baker','Erickson','Pittman','Patrick','Blake','Allison','Taylor','Harper','Romero']
random.shuffle(a)
random.shuffle(b)
random.shuffle(c)
random.shuffle(d)
a = raw_input('Would you like a random username? ')
if a == 'Yes' or 'yes' or 'Yea' or 'yea':
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print 'PROCESSING..'
time.sleep(.5)
print a[3] + b[2] + d[5] + c[4]
else:
print "I didn't have a name …为什么以下引发错误？
for(; 0 ;) System.out.println("guess"); // or
for(;false;) System.out.println("guess"); // or
for(; 1 ;) System.out.println("guess");
但以下运行正常(无限):
for(;true;) System.out.println("guess");
为什么它适用true但不适用false？