说明：
我计划用一个Android程序，打印出平板屏幕的尺寸，大小，dpi等参数信息
效果图：

分辨率: 1280x752DPI: 213物理尺寸(英寸): 对角线 9.4

step1:

package com.example.myapplication;import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import androidx.appcompat.app.AppCompatActivity;public class TestActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_test);printScreenInfo();}private void printScreenInfo() {DisplayMetrics metrics = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(metrics);// 分辨率int widthPixels = metrics.widthPixels;int heightPixels = metrics.heightPixels;// DPI（密度分级）int densityDpi = metrics.densityDpi;// 屏幕物理尺寸计算（英寸）float widthInches = (float) widthPixels / metrics.xdpi;float heightInches = (float) heightPixels / metrics.ydpi;float diagonalInches = (float) Math.sqrt(Math.pow(widthInches, 2) + Math.pow(heightInches, 2));Log.e("ScreenInfo", "分辨率: " + widthPixels + "x" + heightPixels);Log.e("ScreenInfo", "DPI: " + densityDpi);Log.e("ScreenInfo", "物理尺寸(英寸): 对角线 " + String.format("%.1f", diagonalInches));}
}