使用Environment.GetExternalStoragePublicDirectory功能在android中从sdcard发送多个图像

Question

下面找到java文件，我不知道哪里出错了，但我的应用程序不幸停止了，有人可以帮助我哪里和在哪一行我出错了.....下面是我的logcat...详细信息

致命异常：main process:com.example.ankita.implicitIntent，PID:16822 java.lang.nullpointerexception at com.example.ankita.implicitintent.mainactivity.onclick（mainactivity.java:82)at android.view.view.performClick（view.java:4651)at android.view.view$performClick.run（view.java:19310)at android.os.handler.handleCallback（.main（ActivityThread.java:5653)，java.lang.reflect.Method.invokenative（原生方法），java.lang.reflect.Method.invoke(Method.java:515)，com.android.internal.os.zygoteinit$methodandArgsCaller.run(zygoteinit.java:1291)，com.android.internal.os.zygoteinit.main(zygoteinit.java:1107)，dalvik.system.NativePID：16822签名：9

package com.example.ankita.implicitintent;

import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import java.io.File;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity implements View.OnClickListener
{

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

        imgssend=(Button)findViewById(R.id.images_id);

        imgssend.setOnClickListener(this);
    }

    @Override
    public void onClick(View view)
    {
        Intent i=null,chooser=null;
        switch (view.getId())
        {
            case R.id.images_id:
                File Pictures= Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
                String[] listofPictures=Pictures.list();
               Uri uri=null;
                ArrayList<Uri> arraylist=new ArrayList<Uri>();
                for(String picture:listofPictures)
                {
                    uri=uri.parse("file://"+Pictures.toString()+"/"+picture);
                    arraylist.add(uri);
                }
                i=new Intent(Intent.ACTION_SEND_MULTIPLE);
                i.setType("image/*");
                i.putExtra(Intent.EXTRA_STREAM,arraylist);
                chooser=Intent.createChooser(i,"Send multiple");
                startActivity(chooser);
                break;
        }
    }
}


    here is xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.example.ankita.implicitintent.MainActivity">
    <Button
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:text="@string/send_images"
        android:id="@+id/images_id"
        android:layout_gravity="center_horizontal" />
</LinearLayout>

Answer 1

看起来OnClick重写出了问题。为什么不使用按钮的onClick监听器？类似于这样：

public class MainActivity extends AppCompatActivity implements View.OnClickListener
{

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

    Button imgssend=(Button)findViewById(R.id.images_id);

    imgssend.setOnClickListener(new OnClickListener{
        @Override
        public void onClick(View v) {
            Intent i=null,chooser=null;
            File Pictures= Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
            String[] listofPictures=Pictures.list();
            Uri uri=null;
            ArrayList<Uri> arraylist=new ArrayList<Uri>();
            for(String picture:listofPictures)
            {
                uri=uri.parse("file://"+Pictures.toString()+"/"+picture);
                arraylist.add(uri);
            }
            i=new Intent(Intent.ACTION_SEND_MULTIPLE);
            i.setType("image/*");
            i.putExtra(Intent.EXTRA_STREAM,arraylist);
            chooser=Intent.createChooser(i,"Send multiple");
            startActivity(chooser);
        }
    });
}
}