AndroidカスタマイズのLinearLayout + XMLから属性(attribute)を取得して表示させる ref: https://qiita.com/xu1718191411/items/4c1a7c322ef3c3db8908

file0.txt

class MyLinerLayout extends LinearLayout {

    private LayoutInflater mLayoutInflater;
    private Resources mResources;
    public MyLinerLayout(Context context) {
        super(context);
    }

    public MyLinerLayout(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        initialize(attrs,0);
    }

    public MyLinerLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initialize(attrs,defStyleAttr);
    }

    private void initialize(AttributeSet attrs, int defStyleAttr){
        int r = 255;
        int g = 255;
        int b = 255;
        if(attrs != null){
            String packageName = "http://www.mrway.net/syoui";
            r = attrs.getAttributeIntValue(packageName,"r",255);
            g = attrs.getAttributeIntValue(packageName,"g",255);
            b = attrs.getAttributeIntValue(packageName,"b",255);
        }

        mResources  = getContext().getResources();
        mLayoutInflater     = LayoutInflater.from(getContext());
        View view   = mLayoutInflater.inflate(R.layout.my_liner_layout, this);
        ((TextView) view.findViewById(R.id.color)).setText(r+":"+g+":"+b);

        int backgroundColor = Color.argb(255,r,g,b);
        ((LinearLayout) view.findViewById(R.id.colorLayout)).setBackgroundColor(backgroundColor);

    }


}

file1.txt

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
              android:id="@+id/colorLayout"
              xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
            <TextView
                android:id="@+id/color"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:text="white"/>
</LinearLayout>

file2.txt

public class foundation_activity_get_attribute_from_xml extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_foundation_get_attribute_from_xml);
    }

}

file3.txt

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.syoui.imagetab.foundation.activity.foundation_activity_get_attribute_from_xml">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">


    <com.example.syoui.imagetab.foundation.activity.MyLinerLayout
        xmlns:color="http://www.mrway.net/syoui"
        color:r="238"
        color:g="34"
        color:b="12"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
    </com.example.syoui.imagetab.foundation.activity.MyLinerLayout>

    <com.example.syoui.imagetab.foundation.activity.MyLinerLayout
        xmlns:color="http://www.mrway.net/syoui"
        color:r="239"
        color:g="95"
        color:b="107"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
    </com.example.syoui.imagetab.foundation.activity.MyLinerLayout>


    <com.example.syoui.imagetab.foundation.activity.MyLinerLayout
        xmlns:color="http://www.mrway.net/syoui"
        color:r="248"
        color:g="186"
        color:b="0"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
    </com.example.syoui.imagetab.foundation.activity.MyLinerLayout>


</LinearLayout>
</android.support.constraint.ConstraintLayout>