android studio setContenView

Question

So im trying to create a login page for my app and i'm implementing it on Android Studio but it receives an error saying cant not resolve symbol in setContentView. I have been cracking my head up for several hours but i still cant figure what wrong with it. setContentView(R.layout.activity_main); right here at this line, it says activity_main cant not resolve as a variable even though i name my xml file is exactly the same with it. here is my code,

package com.example.tieulyphidep.treasurehunters;

import android.app.ActionBar;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.R;

public class login extends ActionBarActivity implements View.OnClickListener{


    Button bLoggin,buttonSignup;
    EditText EditTextUserName, EditTextPassword;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bLoggin = (Button) findViewById(R.id.buttonLogin);
        buttonSignup = (Button) findViewById(R.id.buttonSignup);
        EditTextUserName =(EditText) findViewById(R.id.EditTextUserName);
        EditTextPassword =(EditText) findViewById(R.id.EditTextPassword);

        buttonLogin.setOnClickListener(this);
        buttonSignup.setOnClickListener(this);


    }
    @Override
    public void onClick(View v) {
    switch(v.getId()){
        case R.id.buttonLogin:
            break;
        case R.id.buttonSignup:
            startActivity(new Intent(this, register.class));
            break;
    }
    }


}

Answer 1

You imported R as import android.R;, but you want to import com.example.tieulyphidep.R

Just erase the line of import android.R; and Android Studio will suggest you to import the good one.

Note also that a class should start by an upcase letter and end by the mother class, like LoginActivity.

Answer 2

Do you have a layout file in your layout.xml titled activity_main? This piece of code:

setContentView(R.layout.activity_main);

is basically saying, "Hey, i'm a java class. I want to look like this file in my layout directory: activity_main"

Now, if you don't have an activity_main, you will definitely get an error.

If you already have the activity_main file in your layout, there are a few steps I suggest you take:

• Clean your project: Build->Clean Project
• Rebuild your project Build->Rebuild project
• Restart android studio

I also noted this:

import android.R;

You shouldn't be importing that.

Here's what your code should look like:

package com.USERNAME.loginregister;

import android.app.AlertDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


public class Login extends ActionBarActivity implements View.OnClickListener {
    Button bLogin;
    TextView registerLink;
    EditText etUsername, etPassword;

    UserLocalStore userLocalStore;

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

        bLogin = (Button) findViewById(R.id.bLogin);
        etUsername = (EditText) findViewById(R.id.etUsername);
        etPassword = (EditText) findViewById(R.id.etPassword);
        registerLink = (TextView) findViewById(R.id.tvRegisterLink);

        bLogin.setOnClickListener(this);
        registerLink.setOnClickListener(this);

        userLocalStore = new UserLocalStore(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.bLogin:
                String username = etUsername.getText().toString();
                String password = etPassword.getText().toString();

                User user = new User(username, password);

                authenticate(user);
                break;
            case R.id.tvRegisterLink:
                Intent registerIntent = new Intent(Login.this, Register.class);
                startActivity(registerIntent);
                break;
        }
    }

According to the link you gave me, here is the full project code:

https://github.com/tonikami/LoginRegister

Best of luck,

{Ruchir}