通過 Class 名稱作為屬性 XML 在 Android

Question

我有擴展一個 class 的類

public abstract class FatherClass{
    int num;
    FatherClass(int num){
        this.num= num;
    }   
}

public class FirstSonClass extend FatherClass{
    FirstSonClass(int num){
        super(num)
    }
}

public class SecondSonClass extend FatherClass{
    SecondSonClass(int num){
        super(num)
    }
}

當我的程序啟動時，它應該創建一個兒子的 static 實例。

public class MainActivity {
    public Static FatherClass STATIC_SON;

    @override
    protected void onCreate(Bundle savedInstance){
        super.onCreate(savedInstanceState);
        setTheme(R.style.AppTheme);
        setContentView(R.layout.activity_main);
        
        // I got this condition from external 
        if(loadExternalCondition()){
            STATIC_SON = new FirstSonClass(4);
        }else {
            STATIC_SON = new SecondSonClass(43);
    }

}

現在在一個Fragment中，我有一個customView ，只有當object是FirstSonClass customView 我不知道該type應該采用哪種格式。 我想把它串起來並在這里傳遞。 在 CustomView class 中，也許我可以以某種方式生成 class 名稱。

<LinearLayout

    <com.whatEver.CustomView
        android:id="@+id/first_view"
        app:type="FirstSonClass"

    </com.whatEver.CustomView>


    <com.whatEver.CustomView
        android:id="@+id/second_view"
        app:type="SecondSonClass"

    </com.whatEver.CustomView>
</LinearLayout>

Now I just want that customView decide to show itself depending on the static class, and the passed class, if the both instanced from the same class then it should shows itself, otherwise hide itself.

public CustomView(context, AttributeSet attrs){
     super(context,attrs);
     init(context,attrs);
}

private init(context, AttributeSet attrs){
     TypedArray typedArray = context.obtainStyledAttributes(atrrs, R.styleable.CustomView);
    try {
         FatherClass father =typedArray.getClass(R.styleable,CustomView_type);
        }
    } finally {
        typedArray.recycle();
    }    

    if(MainActivity.STATIC_SON instanceOf father){
       this.show()
    }else {
       this.hide()
    }
}

我的目標是：

當STATIC_SON是 instanceOf FirstSonClass然后顯示firstView 。 並且 instanceOf SecondSonClass顯示secondView否則不顯示任何內容。

Answer 1

無需創建實例來檢查類型， object instanceOf class

private init(context, AttributeSet attrs){
    if(MainActivity.STATIC_SON instanceOf FirstSonClass){
       this.show()
    }else {
       this.hide()
    }
}