Android进度条不显示

我使用firebase发布某个日期，我需要在上传数据时使用进度对话框指示用户。我导入进度对话框，我需要在上传前显示它，并在上传后关闭它。但是，“进度”对话框根本不会出现

谁能告诉我哪里出错了，谢谢

private ProgressDialog progressDialog;
progressDialog = new ProgressDialog(this);


public void postHelp() {

    progressDialog.setMessage("Posting your request...");
    progressDialog.show();

    final String postTitle = title.getText().toString().trim();
    final String postDesc = desc.getText().toString().trim();
    final String postAddress = address.getText().toString().trim();
    final String postPhone = phone.getText().toString().trim();

    //check input fields
    if (!TextUtils.isEmpty(postTitle) && !TextUtils.isEmpty(postDesc)
            && !TextUtils.isEmpty(postAddress) && !TextUtils.isEmpty(postPhone)) {

        final DatabaseReference newRequest = database.push();
        mDatabaseUser.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                newRequest.child("Title").setValue(postTitle);
                newRequest.child("Desc").setValue(postDesc);
                newRequest.child("Address").setValue(postAddress);
                newRequest.child("Phone").setValue(postPhone);
                progressDialog.dismiss();
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });
        Intent main = (new Intent(AddPostActivity.this,MainActivity.class));
        main.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(main);
    }
}

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调用对话框生成器，如下所示：

AlertDialog.Builder diaog = new AlertDialog.Builder(this,android.R.style.Theme_DeviceDefault_Dialog)
            .setTitle(title)
            .setMessage(message)
            .setPositiveButton(okBtn, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {

                }
            })
            .setCancelable(false)
            ;

然后

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@MarcGV您可以在android o中找到它。Opost完整的代码…您在活动中在哪里使用

这个
？
dialog.show();
dialog.dismiss();