java Android studio：找不到符号变量工具栏
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Android studio: cannot find symbol variable toolbar
提问by M.Jun
I'm a newbie in android studio and I'm following the tutorial guide androidhive. However I'm stucked at the LoginActivity.java part and the author doesnt feel like want to solve it as well. The thing is that when I compile the code,
我是 android studio 的新手，我正在关注教程指南 androidhive。但是我被困在 LoginActivity.java 部分，作者也不想解决它。问题是当我编译代码时，
Error:(41, 54) error: cannot find symbol variable toolbar
错误：(41, 54) 错误：找不到符号变量工具栏
showed up and highlight all the code with R.id, if I delete the toolbar code:
如果我删除工具栏代码，则会显示并突出显示带有 R.id 的所有代码：
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
the code can be compiled but then when you install and open it in the phone it will crash. I've read through a lot of thread and all they said is clean the project or rebuild the gradle, but it is not working.
代码可以编译，但是当您在手机中安装并打开它时，它会崩溃。我已经阅读了很多线程，他们所说的只是清理项目或重建 gradle，但它不起作用。
LoginActivity.java
登录活动.java
package com.testapps.basicsinter;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
public class LoginActivity extends AppCompatActivity {
private EditText inputEmail, inputPassword;
private FirebaseAuth auth;
private ProgressBar progressBar;
private Button btnSignup, btnLogin, btnReset;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Get Firebase auth instance
auth = FirebaseAuth.getInstance();
if (auth.getCurrentUser() != null) {
startActivity(new Intent(LoginActivity.this, MainActivity.class));
finish();
}
// set the view now
setContentView(R.layout.activity_login);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
inputEmail = (EditText) findViewById(R.id.email);
inputPassword = (EditText) findViewById(R.id.password);
progressBar = (ProgressBar) findViewById(R.id.progressBar);
btnSignup = (Button) findViewById(R.id.btn_signup);
btnLogin = (Button) findViewById(R.id.btn_login);
btnReset = (Button) findViewById(R.id.btn_reset_password);
//Get Firebase auth instance
auth = FirebaseAuth.getInstance();
btnSignup.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(LoginActivity.this, SignupActivity.class));
}
});
btnReset.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(LoginActivity.this, ResetPasswordActivity.class));
}
});
btnLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String email = inputEmail.getText().toString();
final String password = inputPassword.getText().toString();
if (TextUtils.isEmpty(email)) {
Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
return;
}
if (TextUtils.isEmpty(password)) {
Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
return;
}
progressBar.setVisibility(View.VISIBLE);
//authenticate user
auth.signInWithEmailAndPassword(email, password)
.addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
// If sign in fails, display a message to the user. If sign in succeeds
// the auth state listener will be notified and logic to handle the
// signed in user can be handled in the listener.
progressBar.setVisibility(View.GONE);
if (!task.isSuccessful()) {
// there was an error
if (password.length() < 6) {
inputPassword.setError(getString(R.string.minimum_password));
} else {
Toast.makeText(LoginActivity.this, getString(R.string.auth_failed), Toast.LENGTH_LONG).show();
}
} else {
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
startActivity(intent);
finish();
}
}
});
}
});
}
}
activity_login.xml
活动登录.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.testapps.basicsinter.LoginActivity">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@color/colorPrimary"
android:gravity="center"
android:orientation="vertical"
android:padding="@dimen/activity_horizontal_margin">
<ImageView
android:layout_width="@dimen/logo_w_h"
android:layout_height="@dimen/logo_w_h"
android:layout_gravity="center_horizontal"
android:layout_marginBottom="30dp"
android:src="@mipmap/ic_launcher" />
<android.support.design.widget.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="@+id/email"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:hint="@string/hint_email"
android:inputType="textEmailAddress"
android:textColor="@android:color/white"
android:textColorHint="@android:color/white" />
</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="@+id/password"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:hint="@string/hint_password"
android:inputType="textPassword"
android:textColor="@android:color/white"
android:textColorHint="@android:color/white" />
</android.support.design.widget.TextInputLayout>
<!-- Login Button -->
<Button
android:id="@+id/btn_login"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dip"
android:background="@color/colorAccent"
android:text="@string/btn_login"
android:textColor="@android:color/black" />
<Button
android:id="@+id/btn_reset_password"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dip"
android:background="@null"
android:text="@string/btn_forgot_password"
android:textAllCaps="false"
android:textColor="@color/colorAccent" />
<!-- Link to Login Screen -->
<Button
android:id="@+id/btn_signup"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dip"
android:background="@null"
android:text="@string/btn_link_to_register"
android:textAllCaps="false"
android:textColor="@color/white"
android:textSize="15dp" />
</LinearLayout>
<ProgressBar
android:id="@+id/progressBar"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_gravity="center|bottom"
android:layout_marginBottom="20dp"
android:visibility="gone" />
</android.support.design.widget.CoordinatorLayout>
AndroidManifest.xml
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.testapps.basicsinter">
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".LoginActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity" />
<activity android:name=".SignupActivity"></activity>
</application>
</manifest>
build.gradle
构建.gradle
apply plugin: 'com.android.application'
android {
compileSdkVersion 25
buildToolsVersion "25.0.3"
defaultConfig {
applicationId "com.testapps.basicsinter"
minSdkVersion 16
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.google.firebase:firebase-auth:10.0.1'
compile 'com.android.support:appcompat-v7:25.3.1'
compile 'com.android.support:design:25.3.1'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
testCompile 'junit:junit:4.12'
}
apply plugin: 'com.google.gms.google-services'
回答by Mahdi-Malv
According to hereyou should include Toolbar in your layout.
根据here，您应该在布局中包含工具栏。
First make a toolbar layout.my_toolbar.xml
首先做一个工具栏布局。my_toolbar.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:orientation="vertical">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:minHeight="?attr/actionBarSize"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:titleTextColor="@android:color/white"
android:background="?attr/colorPrimary">
</android.support.v7.widget.Toolbar>
<!-- Layout for content is here. This can be a RelativeLayout -->
</LinearLayout>
Then include it in your layout (in your case activity_login.xml)
然后将其包含在您的布局中（在您的情况下activity_login.xml）
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.testapps.basicsinter.LoginActivity">
<include
layout="@layout/my_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<!--Rest of your layout content-->
</android.support.design.widget.CoordinatorLayout>
Then you can use Toolbar.
然后你可以使用Toolbar.
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
回答by ivanleoncz
It seems that none of your UI elements in activity_login.xml, has the id toolbarthat you are mentioning here:
中的任何 UI 元素似乎都没有您在此处提到activity_login.xml的 ID toolbar：
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
Also, I believe that you repeated the manifest file, when in fact, you wanted to show the gradle file on the description of your question :).
另外，我相信您重复了清单文件，而实际上，您想在问题描述中显示 gradle 文件:)。
回答by Abhi
Toolbar element is missing in activity_login.xml. The codes for toolbar are
中缺少工具栏元素activity_login.xml。工具栏的代码是
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay"
app:elevation="0dp">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimaryDark"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
If any other errors occur, comment below.
如果发生任何其他错误，请在下面评论。
回答by lonelearner
I have done the tutorial before and here is how I work around it. The gist is in the last step, but I recommend changing all the following code below.
我之前已经完成了本教程，这里是我解决它的方法。要点在最后一步，但我建议更改下面的所有代码。
First, under your manifest
首先，在您的清单下
<activity android:name=".LoginActivity"
android:theme="@style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Second, remove the code, unless you need toolbar for compelling reasons, I don't see a point of including it in.
其次，删除代码，除非出于令人信服的原因需要工具栏，否则我认为没有必要将其包含在内。
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
Third, replace the coordinator layout with LinearLayout and add in the orientation to be vertical
三、用LinearLayout替换coordinator布局，添加方向为垂直
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
Lastly and the most important step, add the following to build.gradle (app). At my time, it was 24.0.0. The current version as of date is 26.1.0. Please adjust accordingly to the appcompt version
最后也是最重要的一步，将以下内容添加到 build.gradle (app)。在我那个时候，它是 24.0.0。截止日期的当前版本是 26.1.0。请根据appcompt版本进行相应调整
compile 'com.android.support:design:26.1.0'
implementation 'com.android.support:appcompat-v7:26.1.0'
回答by DragonFire
For me it was adding the following to the imports.
对我来说，它是在导入中添加以下内容。
import android.support.v7.widget.Toolbar;
Sometimes when I comment some code and auto format using command+option+l - the imports are removed automatically but when I remove the commenting problem arises.
有时，当我使用 command+option+l 注释某些代码和自动格式时 - 导入会自动删除，但是当我删除注释时会出现问题。
Hope this helps someone.
希望这可以帮助某人。
