将像素转换为dp使用TypedValue。

正如文档中提到的:动态类型数据值的容器。

并使用applyDimension方法:

public static float applyDimension (int unit, float value, DisplayMetrics metrics) 

将一个保存维度的已解包的复杂数据值转换为其最终浮点值，如下所示:

Resources resource = getResources();
float dp = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, 69, resource.getDisplayMetrics());

希望能有所帮助。

Java代码:

// Converts 14 dip into its equivalent px
float dip = 14f;
Resources r = getResources();
float px = TypedValue.applyDimension(
    TypedValue.COMPLEX_UNIT_DIP,
    dip,
    r.getDisplayMetrics()
);

芬兰湾的科特林代码:

 val dip = 14f
 val r: Resources = resources
 val px = TypedValue.applyDimension(
     TypedValue.COMPLEX_UNIT_DIP,
     dip,
     r.displayMetrics
 )

芬兰湾的科特林扩展:

val Number.toPx get() = TypedValue.applyDimension(
  TypedValue.COMPLEX_UNIT_DIP,
  this.toFloat(),
  Resources.getSystem().displayMetrics)

更优雅的方法是使用kotlin的扩展函数

/**
 * Converts dp to pixel
 */
val Int.dpToPx: Int get() = (this * Resources.getSystem().displayMetrics.density).toInt()

/**
 * Converts pixel to dp
 */
val Int.pxToDp: Int get() = (this / Resources.getSystem().displayMetrics.density).toInt()

用法:

println("16 dp in pixel: ${16.dpToPx}")
println("16 px in dp: ${16.pxToDp}")

最好放在Util.java类中

public static float dpFromPx(final Context context, final float px) {
    return px / context.getResources().getDisplayMetrics().density;
}

public static float pxFromDp(final Context context, final float dp) {
    return dp * context.getResources().getDisplayMetrics().density;
}

开发者文档提供了如何将dp单位转换为像素单位的答案:

在某些情况下，您需要用dp表示尺寸，然后 把它们转换成像素。dp单位到屏幕像素的转换是 简单: Px = dp * (dpi / 160)

提供了两个代码示例，一个Java示例和一个Kotlin示例。下面是Java示例:

// The gesture threshold expressed in dp
private static final float GESTURE_THRESHOLD_DP = 16.0f;

// Get the screen's density scale
final float scale = getResources().getDisplayMetrics().density;
// Convert the dps to pixels, based on density scale
mGestureThreshold = (int) (GESTURE_THRESHOLD_DP * scale + 0.5f);

// Use mGestureThreshold as a distance in pixels...

Kotlin的例子:

// The gesture threshold expressed in dp
private const val GESTURE_THRESHOLD_DP = 16.0f
...
private var mGestureThreshold: Int = 0
...
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    // Get the screen's density scale
    val scale: Float = resources.displayMetrics.density
    // Convert the dps to pixels, based on density scale
    mGestureThreshold = (GESTURE_THRESHOLD_DP * scale + 0.5f).toInt()

    // Use mGestureThreshold as a distance in pixels...
}

我从Java例子中创建的Java方法工作得很好:

/**
 * Convert dp units to pixel units
 * https://developer.android.com/training/multiscreen/screendensities#dips-pels
 *
 * @param dip input size in density independent pixels
 *            https://developer.android.com/training/multiscreen/screendensities#TaskUseDP
 *
 * @return pixels
 */
private int dpToPixels(final float dip) {
    // Get the screen's density scale
    final float scale = this.getResources().getDisplayMetrics().density;
    // Convert the dps to pixels, based on density scale
    final int pix = Math.round(dip * scale + 0.5f);
    
    if (BuildConfig.DEBUG) {
        Log.i(DrawingView.TAG, MessageFormat.format(
                "Converted: {0} dip to {1} pixels",
                dip, pix));
    }
    
    return pix;
}

这个问题的其他几个答案提供了与这个答案类似的代码，但其他答案中没有足够的支持文档，让我知道其他答案中的一个是否正确。公认的答案也不同于这个答案。我认为开发人员文档已经清楚地说明了Java解决方案。

在Compose中也有一个解决方案。Compose中的密度为设备无关像素(dp)和像素之间的转换提供了一行解决方案。

val sizeInPx = with(LocalDensity.current) { 16.dp.toPx() }

((MyviewHolder) holder).videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
    @Override
    public void onPrepared(final MediaPlayer mediaPlayer) {
        mediaPlayer.setLooping(true);
        ((MyviewHolder) holder).spinnerView.setVisibility(View.GONE);
        mediaPlayer.setOnVideoSizeChangedListener(new MediaPlayer.OnVideoSizeChangedListener() {
           @Override
           public void onVideoSizeChanged(MediaPlayer mp, int width, int height) {
               /*
               * add media controller
               */
               MediaController controller = new MediaController(mContext);
               float density = mContext.getResources().getDisplayMetrics().density;
               float px = 55 * density;
               // float dp = somePxValue / density;
               controller.setPadding(0, 0, 0, (int) (px));
               ((MyviewHolder) holder).videoView.setMediaController(controller);
            }
        });
    }
});