Question

I try to use ternary operator to change the textcolor of button. Something like that: here is the xml.

leaves :: Tree a -> (Int, [a])
leaves''' Nil = (1, [])
leaves''' (Leaf a) = (1, [a])
leaves''' (Br l r) = let (n1, resl) = leaves''' l
                         (n2, resr) = leaves''' r
                     in (n1 + n2 + 1, resl ++ resr)

But the colors are not set correctly. I get some wierd purple colors instead.

I tried

<Button
    android:id="@+id/actionButton"
    android:layout_width="113dp"
    android:layout_height="30dp"
    android:background="@drawable/button"
    android:backgroundTint="@{selected ? R.color.white : R.color.turquoise}"
    android:text="@{selected ? &quot;Selected &quot; : &quot;Select &quot;}"
    android:textColor="@{selected ? @color/white : @color/turquoise}"
    android:onClick="@{(view) -> handler.selectClick(view)}"/>

with same result.
How should I do it?

Answer 1

你的第一个变种应该可以正常工作。您可以参考this doc的“资源”一章。这是一个完整的工作示例。

<强> colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    ...
    <color name="foo">#fff</color>
    <color name="bar">#000</color>
</resources>

<强> main_activity.xml

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

    <data>
        <variable name="selected" type="boolean" />
        <variable name="button2" type="String" />
    </data>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_a"
            android:onClick="switchColor"
            android:text="Click me"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_b"
            android:textColor="@{selected ? @color/foo : @color/bar}"
            android:text="@{button2}"/>

    </LinearLayout>
</layout>

<强> ActivityMain.class

public class ActivityMain extends AppCompatActivity {

    public static final String TAG = "MainActivity";

    MainActivityBinding mBinding;
    boolean mSelected;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mBinding = DataBindingUtil.setContentView(this, R.layout.main_activity);
        mBinding.setButton2("Don't click me please!");
    }

    public void switchColor(View view) {
        mBinding.setSelected(mSelected = !mSelected);
    }
}

Data binding setting colors

1 个答案: