安卓：改变按钮背景编程 [英] Android: change button background programmatically

问题描述

我有这个颜色的资源文件

I have this resource file for colors

<resources>
    <color name="CLR_BLUE">#00f</color>
    <color name="CLR_RED">#f00</color>
    <color name="CLR_GREEN">#0f0</color>
    <color name="CLR_YELLOW">#ff0</color>
    <color name="CLR_BLUE_DARK">#00a</color>
    <color name="CLR_RED_DARK">#a00</color>
    <color name="CLR_GREEN_DARK">#0a0</color>
    <color name="CLR_YELLOW_DARK">#aa0</color>
</resources>

和该方法被调用，当用户点击四个彩色的按钮

And this method that gets called when the user clicks one of four colored Buttons

private void changeBackground(Button pressedBtn)
{
    int oldColor = 0;
    int newColor = 0;

    if(pressedBtn == greenBtn) {
        oldColor = R.color.CLR_GREEN;
        newColor = R.color.CLR_GREEN_DARK;
    }
    else if (pressedBtn == redBtn) {
        oldColor = R.color.CLR_RED;
        newColor = R.color.CLR_RED_DARK;
    }
    else if (pressedBtn == yellowBtn) {
        oldColor = R.color.CLR_YELLOW;
        newColor = R.color.CLR_YELLOW_DARK;
    }
    else if (pressedBtn == blueBtn) {
        oldColor = R.color.CLR_BLUE;
        newColor = R.color.CLR_BLUE_DARK;
    }
    else return;

    pressedBtn.setBackgroundResource(newColor);
    SystemClock.sleep(500);
    pressedBtn.setBackgroundResource(oldColor);

}

问题是按钮的颜色时pressed不会改变。
我走到一个调试器，它实际上达到的方法正确的点，所以这不是一个问题。我认为这个问题是在 pressedBtn.setBackgroundResource（newColor），但我不明白为什么。

PS：无论如何，如果你有一个更好的解决方案来改变按钮颜色时pressed，经过半秒，变回原来的颜色，让我知道

PS: Anyway, if you have a better solution to change a button color when pressed and, after a half second, change back to original color, let me know.

推荐答案

您可以使用像下面这样的XML文件，为您的按钮来创建的状态。

You could use an xml file like one below, to create states for your button.

有关属性提供的信息是这里
您只需将此XML文件复制到可绘制文件夹中的项目，将其命名例如custom_button.xml，并以

The info about attributes available is here. You simply copy this xml file to your drawables folder in your project, name it for example custom_button.xml, and reference it in your layout with

的android：背景=@绘制/ custom_button

下面是xml文件...

Here is xml file...

<?xml version="1.0" encoding="utf-8"?>
<selector
xmlns:android="http://schemas.android.com/apk/res/android">

<item android:state_pressed="true" >
    <shape android:shape="rectangle">
        <solid
            android:color="#00ff00" />
        <stroke
            android:width="5dp"
            android:color="#ff0000"
            android:dashWidth="3dp"
            android:dashGap="2dp" />
    </shape>
</item>

<item android:state_focused="true" >
    <shape>
        <gradient
            android:endColor="#ffffff"
            android:centerColor="#ffffff"
            android:startColor="#ffffff"
            android:angle="270" />
        <stroke
            android:width="3dp"
            android:color="#00ff00" />
        <corners
            android:radius="5dp" />
        <padding
            android:left="10dp"
            android:top="10dp"
            android:right="10dp"
            android:bottom="10dp" />
    </shape>
</item>

<item>        
    <shape>
        <gradient
            android:endColor="#ffffff"
            android:centerColor="#ffffff"
            android:startColor="#ffffff"
            android:angle="270" />
        <stroke
            android:width="5dp"
            android:color="#00ff00" />
        <corners
            android:radius="5dp" />
    </shape>
</item>

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