Android自定义radiobutton样式，动态添加并设置间距

RadioButton经常用来做单选框，但是系统的样式往往无法满足我们的需求，所以可以自定义样式。

项目代码
比如这种，按钮未点击时，边框带圆角，边框和字体颜色为蓝色，背景为白色。按钮点击后，字体变白色，背景变蓝色。下面就来讲讲如何实现。

新建一个共用的布局文件 view_radio_button_item.xml

<?xml version="1.0" encoding="utf-8"?>
<com.example.administrator.radiogroupdemo.GridRadioButton
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:textColor="@color/sel_currency"
	android:textSize="@dimen/txtSize16"
	android:background="@drawable/rb_currency"
	android:button="@null"
	android:gravity="center"
	android:paddingTop="@dimen/dimen5"
	android:paddingBottom="@dimen/dimen5"
	android:paddingStart="@dimen/dimen15"
	android:paddingEnd="@dimen/dimen15" />

button="@null" 消除原本系统的样式，使用 textColor="@color/sel_currency" 和 background="@drawable/rb_currency" 来实现按钮点击与未点击变化的字体颜色和背景色。

sel_currency.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
	<item android:color="@color/white" android:state_checked="true"/>
	<item android:color="@color/rb_select"/>
</selector>

android:state_checked=“true” 表示当前控件被勾选
还有很多其他状态比如
android:state_selected 表示当前控件选择状态
android:state_pressed 表示点击或者触摸该控件的状态

rb_currency.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
	<item android:state_checked="true">
		<shape android:shape="rectangle">
			<solid android:color="@color/rb_select"/>
			<padding android:bottom="@dimen/dimen2" android:left="@dimen/dimen2" android:right="@dimen/dimen2" android:top="@dimen/dimen2"/>
			<corners android:radius="@dimen/dimen2"/>
		</shape>
	</item>

	<item>
		<shape android:shape="rectangle">
			<solid android:color="@color/white"/>
			<stroke android:width="@dimen/dimen1" android:color="@color/rb_select"/>
			<padding android:bottom="@dimen/dimen2" android:left="@dimen/dimen2" android:right="@dimen/dimen2" android:top="@dimen/dimen2"/>
			<corners android:radius="@dimen/dimen2"/>
		</shape>
	</item>
</selector>

动态添加RadioButton前还要使用RadioGroup控件

<com.example.administrator.radiogroupdemo.GridRadioGroup
		android:id="@+id/rb_group"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:columnCount="4"
		app:layout_constraintTop_toTopOf="parent"
		app:layout_constraintLeft_toLeftOf="parent"
		app:layout_constraintRight_toRightOf="parent"/>

最后在代码中添加Button

final List<String> list = new ArrayList<>();
list.add("USD");
list.add("KHR");
list.add("BND");
list.add("VMA");
list.add("CBY");

for (int i = 0; i < list.size(); i++) {
	// 设置间距
	GridRadioGroup.LayoutParams gl = new GridLayout.LayoutParams();
	gl.topMargin = (int) getResources().getDimension(R.dimen.dimen5);
	gl.leftMargin = (int) getResources().getDimension(R.dimen.dimen5);
	gl.rightMargin = (int) getResources().getDimension(R.dimen.dimen5);

	GridRadioButton grbCurrency = (GridRadioButton) getLayoutInflater().inflate(R.layout.view_radio_button_item, null);
	grbCurrency.setId(i);
	grbCurrency.setText(list.get(i));
	grbCurrency.setLayoutParams(gl);

	mRbGroup.addView(grbCurrency);
}

设置勾选监听

mRbGroup.setOnCheckedChangeListener(new GridRadioGroup.OnCheckedChangeListener() {
	@Override
	public void onCheckedChanged(View group, int checkedId) {
		int id = checkedId;
		if (id >= 0 && id < list.size()) Toast.makeText(MainActivity.this, "" + list.get(id), Toast.LENGTH_SHORT).show();
	}
});