how to add button click event in android studio

Question

So I have done some research, and after defining you button as an object by the code

private Button buttonname;
buttonname = (Button) findViewById(R.id.buttonnameinandroid) ;

here is my problem

buttonname.setOnClickListener(this); //as I understand it, the "**this**" denotes the current `view(focus)` in the android program

then your OnClick() event...

Problem:

When I type in the "this", it says:

setOnClickListener (Android.View.view.OnClickListener) in View cannot be applied to (com.helloandroidstudio.MainActivity)

I have no idea why?

here is the code from the .java file

import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

    private Button btnClick;
    private EditText Name, Date;
    private TextView msg, NameOut, DateOut;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btnClick = (Button) findViewById(R.id.button) ;
        btnClick.setOnClickListener(this);
        Name = (EditText) findViewById(R.id.textenter) ;
        Date = (EditText) findViewById(R.id.editText) ;
        msg = (TextView) findViewById(R.id.txtviewOut) ;
        NameOut = (TextView) findViewById(R.id.txtoutName) ;
        DateOut = (TextView) findViewById(R.id.txtOutDate) ;
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }
    }

    public void onClick(View v)
    {
        if (v == btnClick)
        {
            if (Name.equals("") == false && Date.equals("") == false)
            {
                NameOut = Name;
                DateOut = Date;
                msg.setVisibility(View.VISIBLE);
            }
            else
            {
                msg.setText("Please complete both fields");
                msg.setVisibility(View.VISIBLE);
            }
        }
        return;

    }

Answer 1

Button button= (Button)findViewById(R.id.buttonId);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
    // click handling code
   }
});

Answer 2

public class EditProfile extends AppCompatActivity {

    Button searchBtn;
    EditText userName_editText;
    EditText password_editText;
    EditText dob_editText;
    RadioGroup genderRadioGroup;
    RadioButton genderRadioBtn;
    Button editBtn;
    Button deleteBtn;
    Intent intent;
    DBHandler dbHandler;

    public static final String USERID_EDITPROFILE = "userID";

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

        searchBtn = (Button)findViewById(R.id.editprof_searchbtn);
        userName_editText = (EditText)findViewById(R.id.editprof_userName);
        password_editText = (EditText)findViewById(R.id.editprof_password);
        dob_editText = (EditText)findViewById(R.id.editprof_dob);
        genderRadioGroup = (RadioGroup)findViewById(R.id.editprof_radiogroup);
        editBtn = (Button)findViewById(R.id.editprof_editbtn);
        deleteBtn = (Button)findViewById(R.id.editprof_deletebtn);
        intent = getIntent();


        dbHandler = new DBHandler(EditProfile.this);

        setUserDetails();

        deleteBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String username = userName_editText.getText().toString();

                if(username == null){
                    Toast.makeText(EditProfile.this,"Please enter username to delete your profile",Toast.LENGTH_SHORT).show();
                }
                else{
                    UserProfile.Users users = dbHandler.readAllInfor(username);

                    if(users == null){
                        Toast.makeText(EditProfile.this,"No profile found from this username, please enter valid username",Toast.LENGTH_SHORT).show();
                    }
                    else{
                        dbHandler.deleteInfo(username);
                        Intent redirectintent_home = new Intent("com.modelpaper.mad.it17121002.Home");
                        startActivity(redirectintent_home);
                    }
                }
            }
        });

        editBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                String userID_String = intent.getStringExtra(Home.USERID);
                if(userID_String == null){
                    Toast.makeText(EditProfile.this,"Error!!",Toast.LENGTH_SHORT).show();
                    Intent redirectintent_home =  new Intent(getApplicationContext(),Home.class);
                    startActivity(redirectintent_home);
                }
                int userID = Integer.parseInt(userID_String);

                String username = userName_editText.getText().toString();
                String password = password_editText.getText().toString();
                String dob = dob_editText.getText().toString();
                int selectedGender = genderRadioGroup.getCheckedRadioButtonId();
                genderRadioBtn = (RadioButton)findViewById(selectedGender);
                String gender = genderRadioBtn.getText().toString();

                UserProfile.Users users = UserProfile.getProfile().getUser();
                users.setUsername(username);
                users.setPassword(password);
                users.setDob(dob);
                users.setGender(gender);
                users.setId(userID);

                dbHandler.updateInfor(users);
                Toast.makeText(EditProfile.this,"Updated Successfully",Toast.LENGTH_SHORT).show();
                Intent redirectintent_home = new Intent(getApplicationContext(),Home.class);
                startActivity(redirectintent_home);
            }
        });

        searchBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               String username = userName_editText.getText().toString();
               if (username == null){
                   Toast.makeText(EditProfile.this,"Please enter a username",Toast.LENGTH_SHORT).show();
               }
               else{
                   UserProfile.Users users_search = dbHandler.readAllInfor(username);


                   if(users_search == null){
                       Toast.makeText(EditProfile.this,"Please enter a valid username",Toast.LENGTH_SHORT).show();
                   }
                   else{
                       userName_editText.setText(users_search.getUsername());
                       password_editText.setText(users_search.getPassword());
                       dob_editText.setText(users_search.getDob());
                       int id = users_search.getId();
                       Intent redirectintent = new Intent("com.modelpaper.mad.it17121002.EditProfile");
                       redirectintent.putExtra(USERID_EDITPROFILE,Integer.toString(id));
                       startActivity(redirectintent);
                   }
               }
            }
        });


    }

    public void setUserDetails(){

        String userID_String = intent.getStringExtra(Home.USERID);
        if(userID_String == null){
            Toast.makeText(EditProfile.this,"Error!!",Toast.LENGTH_SHORT).show();
            Intent redirectintent_home = new Intent("com.modelpaper.mad.it17121002.Home");
            startActivity(redirectintent_home);
        }
        int userID = Integer.parseInt(userID_String);
        UserProfile.Users users = dbHandler.readAllInfor(userID);
        userName_editText.setText(users.getUsername());
        password_editText.setText(users.getPassword());
        dob_editText.setText(users.getDob());
    }
}

Answer 3

public class MainActivity extends Activity {

    Button button;

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

        button = (Button) findViewById(R.id.submitButton);
        button.setOnClickListener(new MyClass());

    }

    public class MyClass implements View.OnClickListener {

        @Override
        public void onClick(View v) {

        }

    }
}

Answer 4

//as I understand it, the "this" denotes the current view(focus) in the android program

No, "this" will only work if your MainActivity referenced by this implements the View.OnClickListener, which is the parameter type for the setOnClickListener() method. It means that you should implement View.OnClickListener in MainActivity.

Answer 5

public class MainActivity extends AppCompatActivity implements View.OnClickListener

Whenever you use (this) on click events, your main activity has to implement ocClickListener. Android Studio does it for you, press alt+enter on the 'this' word.

Answer 6

Start your OnClickListener, but when you get to the first set up parenthesis, type new, then View, and press enter. Should look like this when you're done:

Button btn1 = (Button)findViewById(R.id.button1);

btn1.setOnClickListener(new View.OnClickListener() {            
    @Override
    public void onClick(View v) {
//your stuff here.
    }
});