编辑网址-怎么做？

Question

I am working in this code where I want to edit an Url with an EditText and when I press the button that brings me the image. But I'm getting a mistake that saids that the EditText is sending a null value.

public class MainActivity extends AppCompatActivity {

ImageView img;
Bitmap bitmap;
private Button btn;
EditText et_num;

String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num+".png";

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

    img = (ImageView) findViewById(R.id.img);
    et_num = (EditText) findViewById(R.id.et_num);
    btn = (Button) findViewById(R.id.btn);

 btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new GetImageFromURL(img).execute(URLIMAGE);
        }
    });
}

public class GetImageFromURL extends AsyncTask<String, Void, Bitmap> {
    ImageView imgV;

    public GetImageFromURL(ImageView imgV) {
        this.imgV = imgV;
    }

    @Override
    protected Bitmap doInBackground(String... url) {
        String urldisplay = url[0];
        bitmap = null;
        try {
            InputStream srt = new java.net.URL(urldisplay).openStream();
            bitmap = BitmapFactory.decodeStream(srt);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bitmap;
    }

    @Override
    protected void onPostExecute(Bitmap bitmap) {
        super.onPostExecute(bitmap);
        imgV.setImageBitmap(bitmap);
     }
   }
 }

I'm getting this:

 W/System.err: java.io.FileNotFoundException: https://www.avansys.edu.pe/sites/default/files/null.png

Does anyone has an idea of ​​how can I fix it?

Answer 1

You got wrong here:

EditText et_num;
String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num+".png";

change to something like this:

String URLIMAGE = "";

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

    img = (ImageView) findViewById(R.id.img);
    et_num = (EditText) findViewById(R.id.et_num);
    btn = (Button) findViewById(R.id.btn);

 btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) { 
     URLIMAGE  = "https://www.avansys.edu.pe/sites/default/files/"+et_num.getText().toString()+".png";
            new GetImageFromURL(img).execute(URLIMAGE);
        }
    });
}

Added

Remember: You need to check nullPointerException for textView any time you want to get its value.

if(!TextUtils.isEmpty(edt.getText().toString())){
 // Doing something
}

Answer 2

I see two things wrong here.

First, you're hardcoding URLIMAGE at initialization, which means it'll take whatever the et_num variable is at that point and convert it to a String. Since it's null, the String representation is null .

The second problem is that EditText#toString() isn't how you get the text from an EditText instance. You should be using EditText#getText().toString() . So do two things:

1. Since you're only using URLIMAGE in one place, just move the assignment to your click listener.

2. Use et_num.getText() not et_num .

Your onClick() code should look like this:

@Override
public void onClick(View v) {
    String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num.getText()+".png";
   new GetImageFromURL(img).execute(URLIMAGE);
}

Answer 3

1.Place String URLIMAGE; (before onCreate)

2.Place you code inside btn.setOnClickListener also you need to get text from edit text.

 btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num.getText().toString()+".png";

            new GetImageFromURL(img).execute(URLIMAGE);
        }
    });

Answer 4

What you are trying to do, is probably getting value provided in the EditText.

First of all the structure will always give you null, as et_num is not declared yet, so it will be always null in below scenario.

EditText et_num;
String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num+".png";

Change the URLIMAGE to String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"

Then in OnClickListener get the actual value of EditText and append to URL

btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String text = et_num.getText().toString();
            new GetImageFromURL(img).execute(URLIMAGE + text + ".png");
        }
    });

Answer 5

First of all, et_num is an Object(EditText) and not the text. During initialization your URLIMAGE initializes before you init your et_num, so it's null. Remove URLIMAGE at all and replace this:

new GetImageFromURL(img).execute(URLIMAGE);

with this:

String url = "https://www.avansys.edu.pe/sites/default/files/"+et_num.getText()+".png";
new GetImageFromURL(img).execute(url);

Answer 6

put this inside the onClick() method of the button btn

String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num.getText().toString()+".png";

like this

btn.setOnclicklistener(new View.OnClickListener(){
           @Override
        public void onClick(View v) {   
            String URLIMAGE = "https://www.avansys.edu.pe/sites/default/files/"+et_num.getText().toString()+".png";

            new GetImageFromURL(img).execute(URLIMAGE);
      }
       });