AndroidはSdカードを使用します

package com.hiscene.testsd;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Environment;
import android.text.format.Formatter;
import android.widget.Toast;

import java.io.File;

public class MainActivity extends AppCompatActivity {

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

        activity=MainActivity.this;
    }

    //判断SD是否准备就绪
    private boolean SdCardIsReady() {
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            Toast.makeText(activity, "sdcard就绪", Toast.LENGTH_SHORT).show();
            return true;
        } else {
            Toast.makeText(activity, "sdcard不存在或未挂载", Toast.LENGTH_SHORT).show();
            return false;
        }
    }

    //获取SD卡使用内存（单位：字节）
    private long GetUseSpace() {
        File ext = Environment.getExternalStorageDirectory();//SD卡目录
        return ext.getUsableSpace();
    }

    //获取SD卡总内存（单位：字节）
    private long GetTotalSpace() {
        File ext = Environment.getExternalStorageDirectory();//SD卡目录
        return ext.getTotalSpace();
    }

}