您缺少默认密度值160。

    2 px = 3 dip if dpi == 80(ldpi), 320x240 screen
    1 px = 1 dip if dpi == 160(mdpi), 480x320 screen
    3 px = 2 dip if dpi == 240(hdpi), 840x480 screen

换句话说，如果你在纵向模式下设计宽度为160dip的布局，它将在所有ldpi/mdpi/hdpi设备上占屏幕的一半(我认为平板电脑除外)

你的问题是将浮点型转换为int型，失去精度。你还应该与因子相乘，而不是除。

这样做:

int dp = (int)(pixel*getResources().getDisplayMetrics().density);

正如@Tomáš Hubálek提到的; 试着这样做:

DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();    
float dpHeight = displayMetrics.heightPixels / displayMetrics.density;
float dpWidth = displayMetrics.widthPixels / displayMetrics.density;

OR

试试老答案:

Display display = getWindowManager().getDefaultDisplay();
DisplayMetrics outMetrics = new DisplayMetrics ();
display.getMetrics(outMetrics);
         
float density  = getResources().getDisplayMetrics().density;
float dpHeight = outMetrics.heightPixels / density;
float dpWidth  = outMetrics.widthPixels / density;

用这个代替怎么样?

final DisplayMetrics displayMetrics=getResources().getDisplayMetrics();
final float screenWidthInDp=displayMetrics.widthPixels/displayMetrics.density;
final float screenHeightInDp=displayMetrics.heightPixels/displayMetrics.density;

我从谷歌中偶然发现了这个问题，后来我找到了一个适用于API >= 13的简单解决方案。

供日后参考:

Configuration configuration = yourActivity.getResources().getConfiguration();
int screenWidthDp = configuration.screenWidthDp; //The current width of the available screen space, in dp units, corresponding to screen width resource qualifier.
int smallestScreenWidthDp = configuration.smallestScreenWidthDp; //The smallest screen size an application will see in normal operation, corresponding to smallest screen width resource qualifier.

参见配置类参考

编辑:正如Nick Baicoianu所指出的，这将返回屏幕的可用宽度/高度(这应该是大多数使用中有趣的部分)。如果您需要实际的显示尺寸，请坚持顶部的答案。

DisplayMetrics displayMetrics = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);

int width_px = Resources.getSystem().getDisplayMetrics().widthPixels;

int height_px =Resources.getSystem().getDisplayMetrics().heightPixels;

int pixeldpi = Resources.getSystem().getDisplayMetrics().densityDpi;


int width_dp = (width_px/pixeldpi)*160;
int height_dp = (height_px/pixeldpi)*160;

在DP方面获得屏幕宽度和高度，并进行良好的装饰:

步骤1:创建接口

public interface ScreenInterface {

   float getWidth();

   float getHeight();

}

步骤2:创建实现者类

public class Screen implements ScreenInterface {
    private Activity activity;

    public Screen(Activity activity) {
        this.activity = activity;
    }

    private DisplayMetrics getScreenDimension(Activity activity) {
        DisplayMetrics displayMetrics = new DisplayMetrics();
        activity.getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        return displayMetrics;
    }

    private float getScreenDensity(Activity activity) {
        return activity.getResources().getDisplayMetrics().density;
    }

    @Override
    public float getWidth() {
        DisplayMetrics displayMetrics = getScreenDimension(activity);
        return displayMetrics.widthPixels / getScreenDensity(activity);
    }

    @Override
    public float getHeight() {
        DisplayMetrics displayMetrics = getScreenDimension(activity);
        return displayMetrics.heightPixels / getScreenDensity(activity);
    }
} 

第三步:在活动中获取宽度和高度:

Screen screen = new Screen(this); // Setting Screen
screen.getWidth();
screen.getHeight();

如果你只是想知道你的屏幕宽度，你可以在你的开发者选项中搜索“最小屏幕宽度”。你甚至可以编辑它。

用kotlin回答:

  context?.let {
        val displayMetrics = it.resources.displayMetrics
        val dpHeight = displayMetrics.heightPixels / displayMetrics.density
        val dpWidth = displayMetrics.widthPixels / displayMetrics.density
    }

2023答案简化Kotlin:

val widthDp = resources.displayMetrics.run { widthPixels / density }
val heightDp = resources.displayMetrics.run { heightPixels / density }

一行程序:

val (height, width) = resources.displayMetrics.run { heightPixels/density to widthPixels/density }

对于Jetpack撰写:

val (height, width) = LocalConfiguration.current.run { screenHeightDp.dp to screenWidthDp.dp }

这是一个基于前面响应的复制/粘贴函数。

  /**
     * @param context
     * @return the Screen height in DP
     */
    public static float getHeightDp(Context context) {
        DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
        float dpHeight = displayMetrics.heightPixels / displayMetrics.density;
        return dpHeight;
    }

    /**
     * @param context
     * @return the screnn width in dp
     */
    public static float getWidthDp(Context context) {
        DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
        float dpWidth = displayMetrics.widthPixels / displayMetrics.density;
        return dpWidth;
    }

在创作的新世界里

val (height, width) = LocalConfiguration.current.run { screenHeightDp.dp to screenWidthDp.dp }