以 XXXXdigYYMMdd.txt的形式在手机文件目录下新建文件

XXXX为序列号，可以认为是随着文件递增的int，例如1234com171201的形式，代码如下：

MainActivity中 ：

package com.example.wupb.testcreatnewfilebytime;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.TextView;import java.io.File;public class MainActivity extends AppCompatActivity {    private static final String TAG="BBBBB";    private File dir;    private File file;    private String mYYMMDD;    private String lastFileName;    File [] fileLists;    private int sericiousNum;    private String baseName;    String basePath;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initData();        scanFile();    }    public void initData(){        baseName = "WuPengBo";        sericiousNum = 0;        basePath= getFilesDir().getPath();        dir =FileUtils.creatDir(basePath + "/abc");        mYYMMDD=FileUtils.getYYMMDD();    }    public void creat(View v){        scanFile();        if(fileLists.length==0){            sericiousNum = 0000;            Log.i(TAG,"int sericiousNum =="+sericiousNum);        }else {            lastFileName = fileLists[fileLists.length-1].getName();            if(lastFileName.matches("[0-9]{4}WuPengBo[0-9]{6}\\.txt")) {                sericiousNum = Integer.parseInt(lastFileName.substring(0, 4));                Log.i(TAG, "sericiousNum ==" + sericiousNum);            }        }        sericiousNum++;        String finalName = String.format("%04d",sericiousNum) + baseName + mYYMMDD + ".txt";        Log.i(TAG,"finalName = "+finalName);        file = FileUtils.createFile(basePath + "/abc/",finalName);        Log.i(TAG,"file.getName ==" +file.getName());    }    public void scanFile( ){        fileLists= dir.listFiles();        for (int i = 0; i <fileLists.length ; i++) {            Log.i(TAG,"fileName is "+fileLists[i].getName().toString());            lastFileName = fileLists[fileList().length-1].getName();        }    }}

FileUtils:

package com.example.wupb.testcreatnewfilebytime;import android.util.Log;import java.io.File;import java.io.IOException;import java.text.SimpleDateFormat;import java.util.Calendar;import static android.content.ContentValues.TAG;/** * Created by wupb on 2017/12/2. */public class FileUtils {    public static File creatDir(String path){        File file = new File(path);        if(file.exists()){            return file;        }        file.mkdirs();        return file;    }    public static String getYYMMDD(){        Calendar calendar=Calendar.getInstance();        SimpleDateFormat s=new SimpleDateFormat("YYMMdd");        String result = s.format(calendar.getTime());        Log.e(TAG, "getYYMMDD:"+result);        return result;    }    public static File createFile(String path,String name){        File file = new File(path+name);        if(file.exists()){            return  file;        }        try {            file.createNewFile();        } catch (IOException e) {            e.printStackTrace();        }        return file;    }}