小编JXP*_*nix的帖子

如何测试double是否为整数

是否有可能做到这一点?

double variable;
variable = 5;
/* the below should return true, since 5 is an int. 
if variable were to equal 5.7, then it would return false. */
if(variable == int) {
    //do stuff
}
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我知道代码可能不会去这样的事情,但怎么去了?

java math

146
推荐指数
7
解决办法
11万
查看次数

Java,如何指定绝对值和平方根

你如何在java中指定如何制作平方根和绝对值?

这是我有的:

if(variable < 0){
    variable = variable + variable2;
}
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但有没有更简单的方法来获得Java的绝对价值?

variable = |variable|
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java math

7
推荐指数
1
解决办法
12万
查看次数

尝试绘制时出现java NullPointerException

我正在尝试根据随机数组绘制图片.到目前为止,我已经取得了部分成功,因为背景颜色(白色)确实出现了.

但是,图片并没有画出来.相反,我看到的只是白色背景和这个错误:

PixelAvatarGen
XphnX
Black and white or 8-bit color?
0 = B&W, 1 = 8bit
1
Print name to make into avatar.
2
5:2:7:0:3:6:7:0:6:7:7:3:1:4:0:6:5:1:7:4:0:0:5:6:6:3:0:2:3:7:2:4:7:5:4:2:3:6:0:1:4:1:6:4:1:1:1:5:7:5:1:5:4:0:4:5:1:5:6:0:5:4:6:0:0:6:0:0:0:6:7:5:2:6:4:0:1:1:1:7:0:2:1:4:0:2:3:3:3:3:2:6:6:2:6:4:2:7:5:4:7:3:3:3:1:5:1:6:1:3:4:6:0:1:1:2:5:7:4:1:0:2:4:4:4:6:3:7:7:1:0:6:3:6:3:7:6:5:2:5:5:3:5:3:5:4:4:7:0:5:7:4:2:4:5:7:1:0:3:2:7:7:2:3:5:5:2:7:5:6:6:7:4:3:0:7:4:7:1:0:0:7:4:4:3:7:6:0:4:2:7:6:7:3:2:4:2:7:3:0:5:6:6:7:7:2:2:0:2:5:7:6:5:1:0:6:1:5:2:0:7:0:7:0:4:1:0:3:4:3:7:7:4:4:2:7:0:7:4:7:1:6:1:4:4:2:4:7:3:0:4:4:6:6:3:5:
Drawing11
Exception in thread "AWT-EventQueue-0" Drawing11
java.lang.NullPointerException
at xphnx.pixelgen.Screen.paintComponent(Screen.java:25)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JLayeredPane.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at java.awt.GraphicsCallback$PaintCallback.run(Unknown Source)
at sun.awt.SunGraphicsCallback.runOneComponent(Unknown Source)
at sun.awt.SunGraphicsCallback.runComponents(Unknown Source)
at …
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java swing

1
推荐指数
1
解决办法
155
查看次数

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