是否有可能从layout.xml android中的活动中获取变量的值？

Question

I need to know if I can obtain a calculated number from my main activity and access it from my layout.xml.

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    DisplayMetrics displaymetrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
    int height = displaymetrics.heightPixels;
    int width = displaymetrics.widthPixels;
    float margin_top = (1920f/height) * 125;
    String margin_top_str = Float.toString(margin_top) + "dp";
}

layout.xml code

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/app_name"
    android:id="button"
    android:background="#f57878"
    android:textSize="48dp"
    android:layout_alignParentTop="true"
    android:layout_marginTop="@MainActivity.java/margin_top_str"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:textColor="#000000" />

The line android:layout_marginTop="@MainActivity.java/margin_top_str" is not real and is only to show what I need. If what I am asking can be done only in the activity that would work fine too. ps I am a noob. Thanks

Answer 1

No, you can not. You can only reference constants and values from other XML resources but you can't reference java code.

Instead, calculate the value for different screen sizes and put to corresponding res folders in dimens.xml . If it can't be calculated then just set it in runtime through MarginLayoutParams .