'；boolean android.graphics.Bitmap.compress（android.graphics.Bitmap$CompressFormat，int，java.io.OutputStream）和#x27；关于空对象引用

我正在尝试使用Reformation2上载图像，但出现以下错误：

java.lang.NullPointerException:尝试调用虚拟方法 '布尔 android.graphics.Bitmap.compress（android.graphics.Bitmap$CompressFormat， int，java.io.OutputStream）“”在空对象引用上

更新：我设法修复了错误，但我不确定如何将ImageView转换为位图并压缩它。我目前正在使用毕加索将图像加载到ImageView中

My image toString方法：

     private String imagetoString() {
         ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG,100,byteArrayOutputStream);
         byte[] imgByte = byteArrayOutputStream.toByteArray();
         return Base64.encodeToString(imgByte,Base64.DEFAULT);
         }

我的API接口：

public interface ApiUpdateProfile {
    @FormUrlEncoded
    @POST("update_profile.php")
    Call<ProfileUpdate uploadImage(@Field("Photo_Location") String Photo_Location, @Field("Photo_Title") String Photo_Title);
}

我的图像上载方法：

private void uploadImage()
    {
        String Photo_Location = imagetoString();
        String Photo_Title = fullname.toString();

        ApiUpdateProfile apiUpdateProfile = ApiClient.getClient().create(ApiUpdateProfile.class);
        Call<ProfileUpdate call = apiUpdateProfile.uploadImage(Photo_Title, Photo_Location);
        call.enqueue(new Callback<ProfileUpdate>() {
            @Override
            public void onResponse(Call<ProfileUpdate call, Response<ProfileUpdate response) {
                ProfileUpdate profileUpdate = response.body();
                Toast.makeText(ProfileUpdateActivity.this, "Server response " + profileUpdate.getResponse(), Toast.LENGTH_LONG);
            }

            @Override
            public void onFailure(Call<ProfileUpdate call, Throwable t) {
                Toast.makeText(ProfileUpdateActivity.this, "error", Toast.LENGTH_LONG);
            }
        });
    }

private void uploadImage（）
{
字符串Photo_Location=imagetoString（）；
字符串Photo_Title=fullname.toString（）；
ApiUpdateProfile ApiUpdateProfile=ApiClient.getClient（）.create（ApiUpdateProfile.class）；
调用您的
imagetoString
中的
bitmap
对象来自何处？我遵循本教程：它似乎与他一起工作。我不确定我缺少了什么。它是他的
MainActivity
的一个类变量，可能您没有设置它（因此在您的情况下它仍然是
NULL
）.回到该系列的第5部分，检查你是否遗漏了什么。
private void uploadImage()
    {
        String Photo_Location = imagetoString();
        String Photo_Title = fullname.toString();

        ApiUpdateProfile apiUpdateProfile = ApiClient.getClient().create(ApiUpdateProfile.class);
        Call<ProfileUpdate call = apiUpdateProfile.uploadImage(Photo_Title, Photo_Location);
        call.enqueue(new Callback<ProfileUpdate>() {
            @Override
            public void onResponse(Call<ProfileUpdate call, Response<ProfileUpdate response) {
                ProfileUpdate profileUpdate = response.body();
                Toast.makeText(ProfileUpdateActivity.this, "Server response " + profileUpdate.getResponse(), Toast.LENGTH_LONG);
            }

            @Override
            public void onFailure(Call<ProfileUpdate call, Throwable t) {
                Toast.makeText(ProfileUpdateActivity.this, "error", Toast.LENGTH_LONG);
            }
        });
    }

 <?php

 require "connection.php";

 if($con){  $title = $_POST['Photo_Title'];     $image =
 $_POST['Photo_Location'];

    $upload_path = "images/$title.jpg";

    $sql = "INSERT into employee_profile(Photo_Location, Photo_Title)
        values('$title', '$upload_path');";

    if(mysqli_query($con, $sql))    {       file_put_contents($upload_path,
 base64_decode($image));        echo json_encode(array('response'=>"Image
 uploaded"));       }   else{       echo json_encode(array('response'=>"Image
 upload failed."));     }

 mysqli_close($con); }   ?>