为什么我不能用“new”关键字在Java中创建Color？

Question

I was trying to make a new color in java using

Color temp = new Color(foo.getBackground());

and it kept telling me cannot find symbol.

But this works

Color temp = (foo.getbackground());

Why?

Answer 1

那是因为foo.getBackground()返回一个Color实例，并且没有Color构造函数将Color实例作为参数。

Answer 2

Check this link Color (Java 2 Platform SE v1.4.2) .

If you want this code to work:

Color temp = new Color(foo.getBackground());

foo.getBackground() must return an integer. Since it returns an object Color you have type mismatch.

You can always do:

Color temp = new Color(foo.getbackground().getRGB());

or:

Color color = foo.getBackground();
Color temp = new Color(color.getRed(), color.getGreen(), color.getBlue(),color.getAlpha());

Answer 3

Yes, you can do it, the problem is that maybe foo.getBackground does'nt returns an integer or something similar.

Color c = new Color(23,32,43)

works perfectly

Answer 4

There isn't a constructor for Color that takes just a Color. In the second instance you're assigning a variable that was returned from a function.

Answer 5

The Color class does not have a constructor taking an other instance of Color as an argument, and that is what foo.getBackground() returns. IIRC, the Color class in Java is immutable - so there is simply no point in providing a constructor that would create a copy of an existing Color object.

Answer 6

Apparently the type that foo.getBackground() returns is of type "Color".

While you can of course assign a Color to the variable temp of type Color, at least in java.awt.Color there is not constructor to create a Color from another Color.