问题
Basically I have a login and sign up code for Parse. I'm working off of this tutorial. I have:
LoginSignupActivity.java
package com.androidbegin.parselogintutorial;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.parse.LogInCallback;
import com.parse.ParseException;
import com.parse.ParseUser;
import com.parse.SignUpCallback;
public class LoginSignupActivity extends Activity {
// Declare Variables
Button loginbutton;
Button signup;
String usernametxt;
String passwordtxt;
EditText password;
EditText username;
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the view from main.xml
setContentView(R.layout.main);
// Locate EditTexts in main.xml
username = (EditText) findViewById(R.id.username);
password = (EditText) findViewById(R.id.password);
// Locate Buttons in main.xml
loginbutton = (Button) findViewById(R.id.login);
signup = (Button) findViewById(R.id.signup);
// Login Button Click Listener
loginbutton.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// Retrieve the text entered from the EditText
usernametxt = username.getText().toString();
passwordtxt = password.getText().toString();
// Send data to Parse.com for verification
ParseUser.logInInBackground(usernametxt, passwordtxt,
new LogInCallback() {
public void done(ParseUser user, ParseException e) {
if (user != null) {
// If user exist and authenticated, send user to Welcome.class
Intent intent = new Intent(
LoginSignupActivity.this,
Welcome.class);
startActivity(intent);
Toast.makeText(getApplicationContext(),
"Successfully Logged in",
Toast.LENGTH_LONG).show();
finish();
} else {
Toast.makeText(
getApplicationContext(),
"No such user exist, please signup",
Toast.LENGTH_LONG).show();
}
}
});
}
});
// Sign up Button Click Listener
signup.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// Retrieve the text entered from the EditText
usernametxt = username.getText().toString();
passwordtxt = password.getText().toString();
// Force user to fill up the form
if (usernametxt.equals("") && passwordtxt.equals("")) {
Toast.makeText(getApplicationContext(),
"Please complete the sign up form",
Toast.LENGTH_LONG).show();
} else {
// Save new user data into Parse.com Data Storage
ParseUser user = new ParseUser();
user.setUsername(usernametxt);
user.setPassword(passwordtxt);
user.signUpInBackground(new SignUpCallback() {
public void done(ParseException e) {
if (e == null) {
// Show a simple Toast message upon successful registration
Toast.makeText(getApplicationContext(),
"Successfully Signed up, please log in.",
Toast.LENGTH_LONG).show();
} else {
Toast.makeText(getApplicationContext(),
"Sign up Error", Toast.LENGTH_LONG)
.show();
}
}
});
}
}
});
}
}
And my loginsignup.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:padding="10dip" >
<TextView
android:id="@+id/txtusername"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/Username" />
<EditText
android:id="@+id/username"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/txtusername"
android:inputType="text" />
<TextView
android:id="@+id/txtpassword"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/username"
android:text="@string/Password" />
<EditText
android:id="@+id/password"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/txtpassword"
android:inputType="textPassword" />
<Button
android:id="@+id/login"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/password"
android:text="@string/LoginBtn" />
<Button
android:id="@+id/signup"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/login"
android:text="@string/SignupBtn" />
</RelativeLayout>
When I try to run it I get "string cannot be resolved or is not a field." (String is used as a placeholder). I'm fairy new to Android development. Any help would be great.
回答1:
Instead of-
setContentView(R.layout.main);
write this-
setContentView(R.layout.loginsignup);
回答2:
Try to clear your project.
Remove private libraries from the 3rd party library project if you have any.
Add to build path your Android v4 library.
Then again clear your project.
来源：https://stackoverflow.com/questions/21636036/string-cannot-be-resolved-or-is-not-a-field