AndroidStudio : Cannot resolve symbol MainActivity

Question

I got an error "Cannot resolve symbol MainActivity" on this code.

<activity
        android:name=".MainActivity"          //here
        android:label="@string/app_name"
        android:launchMode="singleTask" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/> 

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.intent.action.VIEW" />

            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />

            <data
                android:host="MainActivity"
                android:scheme="callback" />
        </intent-filter>
    </activity>

Needless to say , MainActivity inherits Activity and package name is correct too.

Why?

Thank you

Here's an image of the directory structure.

Snapshot of the directory structure

What does your package structure look like? Where is MainActivity in that structure? — Bryan Herbst, Jul 30 '14 at 15:42
Take a screenshot of your directory structure within android studio — StuStirling, Jul 30 '14 at 15:47
I tried writing my package structure "com.example.fovoapp.MainActivity" but this error was not fixed. — Yuya Okada, Jul 30 '14 at 15:51
This is my directory structure. http://www.fastpic.jp/images.php?file=4073568203.png — Yuya Okada, Jul 30 '14 at 15:59

score 20 · Answer 1 · answered Jul 30 '14 at 17:22

20

It's possible that your 'src' directory isn't set as a source directory?

Your IDE seems to be seeing your com.example.fovoapp as a simple directory structure instead of a package. Also looking at your linked image, the little "J" on the java files tells me that also. When a java file is set as source usually it shows up as a Class "C".

I could be wrong but make sure you set your src directory as source and that should fix the issue.

answered Jul 30 '14 at 17:22

Miguel

19,133
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11

@MiguelLavigne please explain how to set your src director as source. – DiscDev Mar 01 '16 at 13:43

score 12 · Answer 2 · edited Sep 13 '19 at 16:30

12

package name on AndroidManifest.xml file and your classes must be same.

AndroidManifest.xml header:

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   package="com.ahmet.currencies">

Code:

package com.ahmet.currencies;

import ...;


public class MainActivity extends Activity {}

edited Sep 13 '19 at 16:30

CopsOnRoad

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answered Jul 22 '15 at 12:32

Ahmet Arslan

4,474
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Packages are mainly handled by Gradle – Zoe stands with Ukraine Apr 10 '19 at 13:49

score 2 · Answer 3 · answered Dec 16 '14 at 13:02

2

Maybe you use the wrong path for the src directory.
It should be in the path : ./yourApp/src/main and not ./yourApp/src/androidTest
You can move it manually.

answered Dec 16 '14 at 13:02

Alexandre Gombert

168
1
12

score 2 · Answer 4 · answered Nov 27 '15 at 20:22

project structure, right click on src folder->Mark directory as-> sources root.

Now your mainactivity.java file with 'j' symbol to change to 'c' symbol.

The error was that the project did not have a valid source folder from where it could look for the activity class.

score 2 · Answer 5 · edited Sep 13 '19 at 16:36

2

Clean Caches

File -> Invalidate Caches / Restart...

edited Sep 13 '19 at 16:36

CopsOnRoad

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answered May 03 '19 at 15:37

Nitya Kumar

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14

score 0 · Answer 6 · answered Dec 23 '15 at 05:52

0

In your build.gradle file add the following.

android {
     sourceSets {
            main.java.srcDirs += 'src/<YOUR DIRECTORY NAME>'
        }
...
...
}

answered Dec 23 '15 at 05:52

Naskov

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score 0 · Answer 7 · answered Apr 10 '19 at 13:03

0

set your compatible api level. i also same the face error so i set my api level to 23 in file-> project structure-> app-> flavour -> target sdk version

answered Apr 10 '19 at 13:03

mehak

1

You have to post this as a comment, not an answer. – Elio Lako Apr 10 '19 at 13:07
@cod-e-rection why? It is an answer – Zoe stands with Ukraine Apr 10 '19 at 15:40
@Zoe yes but in this case it was not close to the question. – Elio Lako Apr 11 '19 at 07:55
@cod-e-rection except it is, and it does answer the question for OP, which does make this an answer. – Zoe stands with Ukraine Apr 11 '19 at 08:13

AndroidStudio : Cannot resolve symbol MainActivity

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