BottomSheetDialog控件使用 （底部，可拖动弹窗）

  implementation 'com.google.android.material:material:1.0.0'  

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/sh"
    android:orientation="vertical">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="40dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:text="100首歌"
            android:textStyle="bold" />

        <ImageView
            android:layout_width="24dp"
            android:layout_height="24dp"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:layout_marginRight="10dp"
            android:src="@drawable/error" />
    </RelativeLayout>

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/dialog_recycleView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <corners
        android:topLeftRadius="10dp"
        android:topRightRadius="10dp" />
    <solid android:color="#fff" />
</shape>

显示dialog
private void showSheetDialog() {
        recyclerView = view.findViewById(R.id.dialog_recycleView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        mainAdapter = new MainAdapter(R.layout.item_main, titleList);
        recyclerView.setAdapter(mainAdapter);

        bottomSheetDialog = new BottomSheetDialog(MainActivity.this, R.style.DialogTheme);
        bottomSheetDialog.setContentView(view);
        mDialogBehavior = BottomSheetBehavior.from((View) view.getParent());
        mDialogBehavior.setPeekHeight(getWindowHeight());//dialog的高度
        mDialogBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
            @Override
            public void onStateChanged(@NonNull View view, int i) {
                if (i == BottomSheetBehavior.STATE_HIDDEN) {
                    bottomSheetDialog.dismiss();
                    mDialogBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
                }
            }
            @Override
            public void onSlide(@NonNull View view, float v) {

            }
        });
    }

    private int getWindowHeight() {
        Resources res = MainActivity.this.getResources();
        DisplayMetrics displayMetrics = res.getDisplayMetrics();
        return displayMetrics.heightPixels;
    }

package com.example.bottomsheetdialog;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.res.Resources;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.google.android.material.bottomsheet.BottomSheetBehavior;
import com.google.android.material.bottomsheet.BottomSheetDialog;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private BottomSheetDialog bottomSheetDialog;
    private BottomSheetBehavior mDialogBehavior;
    private RecyclerView recyclerView;
    private MainAdapter mainAdapter;
    private List<String> titleList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.main_btn1).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                initData();
                showSheetDialog1();
                bottomSheetDialog.show();
            }
        });

    }


    private void showSheetDialog1() {
        View view = View.inflate(MainActivity.this, R.layout.dialog_bottomsheet, null);

        recyclerView = view.findViewById(R.id.dialog_recycleView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        mainAdapter = new MainAdapter(R.layout.item_main, titleList);
        recyclerView.setAdapter(mainAdapter);

        bottomSheetDialog = new BottomSheetDialog(MainActivity.this, R.style.DialogTheme);
        bottomSheetDialog.setContentView(view);
        mDialogBehavior = BottomSheetBehavior.from((View) view.getParent());
        mDialogBehavior.setPeekHeight(getPeekHeight());


    }


    /**
     * 弹窗高度，默认为屏幕高度的四分之三
     * 子类可重写该方法返回peekHeight
     *
     * @return height
     */
    protected int getPeekHeight() {
        int peekHeight = getResources().getDisplayMetrics().heightPixels;
        //设置弹窗高度为屏幕高度的3/4
        return peekHeight - peekHeight / 3;
    }

    private void initData() {
        for (int i = 0; i < 110; i++) {
            titleList.add("item" + i);
        }
    }
}

  private int getWindowHeight() {
        Resources res = MainActivity.this.getResources();
        DisplayMetrics displayMetrics = res.getDisplayMetrics();
        return displayMetrics.heightPixels;
    }