Throwing an Exception from OnClickListener

I'm kind of new to java, what I'm trying to do here is sending a Post request everytime a button is pressed. Here's my code

   public class Remotetask extends AppCompatActivity {

    TextView tv;
    Button btn;

    public void PostRequest(String url_from_text) throws IOException {
        String url = url_from_text;
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("User-Agent", "Mozilla/5.0");
        int responseCode = con.getResponseCode();
        BufferedReader in = new BufferedReader(
                new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        //print in String
        tv.setText(response.toString());
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_eve_aioremote);
        btn = (Button) findViewById(R.id.Button1);
        tv = (TextView) findViewById(R.id.textView);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) throws IOException{
                PostRequest("api endpoint");
            }
        });
    }
}

This line here though

public void onClick(View v) throws IOException

Gives me this error here:

error: onClick(View) in cannot implement onClick(View) in OnClickListener overridden method does not throw IOException

I found another post of a guy asking a similar question but the answers really didn't help me out as I'm kind of new to this. Thank you.

Remove that IOException throw from your onclick. Like this

@Override
public void onClick(View v) {
  try {
    PostRequest("api endpoint");
   } catch (IOException e){
        e.printStackTrace();
    }
}

The original method of onClickListener doesn't throw any Exception that's why it is giving error.

How to throw an exception from onClickListener's methods, You cannot throw a checked exception in an overridden method if the initial declaration does not include the throw declaration. You can  The OnClickListener Android button throws a null exception I am having trouble setting an onclicklistener for my Buttons. While some of them are working properly, others are not working. The code shows no errors but when i run the app i am presented with errors in the Log, one of which says NullPointerExcept

throws IOException Please dont throw this in Onclick because you already throw the exception in PostRequest Method

Try this:

 btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v){
        PostRequest("api endpoint");
    }
});

OnClick(view v) throws a null pointer exception. Can anyone help , Hide Copy Code. TextView txt1 = (TextView) findViewById(R.id.userName); EditText txt = (EditText) findViewById(R.id.userName); Both use the  click(view v) is throwing a null pointer exception. have been trying to sort it for hours. but to no avail. I would appriciate if anyone could help me sort this issue. Thanks for you time.

implement try-catch instead of throwing IOException ,

 public class Remotetask extends AppCompatActivity {

 TextView tv;
 Button btn;

 public void PostRequest(String url_from_text) {
 try{
String url = url_from_text;
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
con.setRequestMethod("GET");
con.setRequestProperty("User-Agent", "Mozilla/5.0");
int responseCode = con.getResponseCode();
BufferedReader in = new BufferedReader(
        new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
    response.append(inputLine);
}
in.close();
//print in String
tv.setText(response.toString());
}catch(Exception e)
{
e.printStackTrace();
}
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_eve_aioremote);
btn = (Button) findViewById(R.id.Button1);
tv = (TextView) findViewById(R.id.textView);

btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v){
        PostRequest("api endpoint");
    }
});

}

Tips to fixing a NullPointerException in Java (Android) – FincoApps, A NullPointerException is usually thrown when you try to access a field or a method in a variable or an object that is null. This is The above code will throw a null pointer exception on line 2. public void onClick(View v) {. It is important to understand how to throw exceptions in Java. This will allow you to create higher quality code where errors are checked at compile time instead of runtime, and create custom exceptions that make debugging and recovery easier. How to throw exceptions in Java. Throwing an exception is as simple as using the "throw" statement.

handle error like this

btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
    try {
        PostRequest("api endpoint");
    } catch (Exception e)‏ {
        //error handling code
    }

}
});

Asynchronous Android Programming, The first way is to clear the pending exception with ExceptionClear and continue to release all the native resources, and throw a different exception to be handled in Java by the OnClickListener onClickListener = new OnClickListener​()  Programs can throw a predefined exception class in the System namespace (except where previously noted), or create their own exception classes by deriving from Exception. The derived classes should define at least four constructors: one parameterless constructor, one that sets the message property, and one that sets both the Message and

Try This Code Snippet please remove throw IOException from OnClick

  public class Remotetask extends AppCompatActivity {

    TextView tv;
    Button btn;

    public void PostRequest(String url_from_text) throws IOException {
        String url = url_from_text;
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("User-Agent", "Mozilla/5.0");
        int responseCode = con.getResponseCode();
        BufferedReader in = new BufferedReader(
                new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        //print in String
        tv.setText(response.toString());
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_eve_aioremote);
        btn = (Button) findViewById(R.id.Button1);
        tv = (TextView) findViewById(R.id.textView);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try{
                PostRequest("api endpoint");
                } catch (Exception e)
                  {
                   e.getStackTrace();
                  }
            }
        });
    }
}

Hope this may help you

Null pointer exception When making an intent crash?, View$OnClickListener)' on a null object reference Now what does it on the variable the JVM catches the error and throws the exception . Exception Class. Most programs throw and catch objects that derive from the Exception class. An Exception indicates that a problem occurred, but it is not a serious system problem. Most programs you write will throw and catch Exceptions as opposed to Errors. The Java platform defines the many descendants of the Exception class. These

OnClickListener inside a loop throwing IndexOutOfBounds Exception, For some reason though, setting my OnClickListener inside the loop is causing an OOB exception but from what I see it shouldn't be so I appreciate being  Android Platform. API level 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1. Manifest.permission. Manifest.permission_group. android.accessibilityservice. AccessibilityService.MagnificationController.OnMagnificationChangedListener. AccessibilityService.SoftKeyboardController.OnShowModeChangedListener.

@Onclick annotation throws runtime exception on bind · Issue , I just created a new project targetting 28 , minimum 28. Jetifier enabled and using AndroidX libs. I created a simple fragment with a button and a  A NullPointerException is usually thrown when you try to access a field or a method in a variable or an object that is null. This is simple to understand however, it might be a bit confusing for some programmers.

The Definitive Guide to Firebase: Build Android Apps on Google's , and implement a crash by clicking the button – it will simply throw a runtime exception. public void onClick(View view) { throw new RuntimeException  In java, as a rule, if a method in a class does not throw any exception, then the derived classes can override the behaviour of the method but cannot throw any exception. Overriding a method in a derived classes cannot change the method signature which inclues the return value, parameters and exceptions.

Comments
  • throw a runtimeexeption not a checked exception or handle the exception directly in the onCick method
  • i suggest you use volley or retrofit library instead of manual code
  • That's the first thing I tried, but if I do that I get "error: unreported exception IOException; must be caught or declared to be thrown" for the line "PostRequest("api endpoint");". Thank you so much for the quick reply though.
  • Okay got it! Thank you for the quick solution!
  • If it helped you then mark this as accepted answer so others can take benefit from it.
  • Yup! Got it! Thank you!