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Moving from activity A to activity B and back from activity B to activity A

I'm very new to this and I've been looking around the forum for a while to get an answer to my question but I can't seem to get this working and I would very much appreciate help from your pros :)
As the title specifies I would like to go from activity A to activity B on a button click and from activity B on a button click go back to activity A.
My problem is first of all that I can't even go from activity A to activity B because the app crashes when I press the button. Why?
Second I would like to know if my code for returning from activity B to activity A is correct.
My code to go from activity A to activity B
public Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void ToCV(View v) {
Intent intent = new Intent(this, CV.class);
startActivity(intent);
}
}
And now the code for returning from Activity B to Activity A
public class CV extends AppCompatActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cv);
}
public void GoBack(View v) {
startActivity(new Intent(CV.this,MainActivity.class));
}
}
here is the crash log when i run the app##
2021-03-03 11:29:46.290 4104-4104/com.example.cvapp D/AndroidRuntime: Shutting down VM
2021-03-03 11:29:46.291 4104-4104/com.example.cvapp W/m.example.cvap: Accessing hidden method Lcom/msic/qarth/PatchStore;->createDisableExceptionQarthFile(Ljava/lang/Throwable;)Z (blacklist, JNI)
2021-03-03 11:29:46.291 4104-4104/com.example.cvapp E/m.example.cvap: [qarth_debug:] get PatchStore::createDisableExceptionQarthFile method fail.
2021-03-03 11:29:46.296 4104-4104/com.example.cvapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.cvapp, PID: 4104
java.lang.IllegalStateException: Could not execute method for android:onClick
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414)
at android.view.View.performClick(View.java:6659)
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992)
at android.view.View.performClickInternal(View.java:6631)
at android.view.View.access$3100(View.java:790)
at android.view.View$PerformClick.run(View.java:26187)
at android.os.Handler.handleCallback(Handler.java:907)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:216)
at android.app.ActivityThread.main(ActivityThread.java:7625)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409)
at android.view.View.performClick(View.java:6659) 
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992) 
at android.view.View.performClickInternal(View.java:6631) 
at android.view.View.access$3100(View.java:790) 
at android.view.View$PerformClick.run(View.java:26187) 
at android.os.Handler.handleCallback(Handler.java:907) 
at android.os.Handler.dispatchMessage(Handler.java:105) 
at android.os.Looper.loop(Looper.java:216) 
at android.app.ActivityThread.main(ActivityThread.java:7625) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987) 
Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.cvapp/com.example.cvapp.CV}; have you declared this activity in your AndroidManifest.xml?
at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:2112)
at android.app.Instrumentation.execStartActivity(Instrumentation.java:1757)
at android.app.Activity.startActivityForResult(Activity.java:4803)
at androidx.fragment.app.FragmentActivity.startActivityForResult(FragmentActivity.java:676)
at android.app.Activity.startActivityForResult(Activity.java:4743)
at androidx.fragment.app.FragmentActivity.startActivityForResult(FragmentActivity.java:663)
at android.app.Activity.startActivity(Activity.java:5164)
at android.app.Activity.startActivity(Activity.java:5132)
at com.example.cvapp.MainActivity.ToCV(MainActivity.java:21)
at java.lang.reflect.Method.invoke(Native Method) 
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) 
at android.view.View.performClick(View.java:6659) 
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992) 
at android.view.View.performClickInternal(View.java:6631) 
at android.view.View.access$3100(View.java:790) 
at android.view.View$PerformClick.run(View.java:26187) 
at android.os.Handler.handleCallback(Handler.java:907) 
at android.os.Handler.dispatchMessage(Handler.java:105) 
at android.os.Looper.loop(Looper.java:216) 
at android.app.ActivityThread.main(ActivityThread.java:7625) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987) 
The manifest
`<?xml version="1.0" encoding="utf-8"?>
<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/Theme.CVapp">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

Register your Activity B in the manifest file

Put these lines in your maifest
<activity android:name=".CV"/>

You should register Activity B in your AndroidManifest.xml
Your manifest should look like this:
<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/Theme.CVapp">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".CV"/>
</application>
And also if you want to return from Activity B to Activity A, you can call method ->
finish() - in Activity B and that will destroy Activity B and return to previous activity and that's Activity A.

Error Unknown bits set in runtime_flags: 0x8000 Fail to get file list

I am doing an exercise with tabLayout, a frame has some textlayout and another one has buttons with a scroll. When I try it, it gives me a series of errors that I can't find, I leave you the code and the logcat
2020-01-07 20:20:13.336 27052-27052/? I/om.example.ej1: Late-enabling -Xcheck:jni
2020-01-07 20:20:13.348 27052-27052/? E/om.example.ej1: Unknown bits set in runtime_flags: 0x8000
2020-01-07 20:20:13.561 27052-27052/com.example.ej10 I/Perf: Connecting to perf service.
2020-01-07 20:20:13.578 27052-27114/com.example.ej10 E/Perf: Fail to get file list com.example.ej10
2020-01-07 20:20:13.579 27052-27114/com.example.ej10 E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2020-01-07 20:20:13.579 27052-27114/com.example.ej10 E/Perf: Fail to get file list com.example.ej10
2020-01-07 20:20:13.579 27052-27114/com.example.ej10 E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2020-01-07 20:20:13.691 27052-27052/com.example.ej10 D/AndroidRuntime: Shutting down VM
2020-01-07 20:20:13.694 27052-27052/com.example.ej10 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ej10, PID: 27052
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ej10/com.example.ej10.MainActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3276)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3415)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2022)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:359)
at android.app.ActivityThread.main(ActivityThread.java:7418)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:935)
Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:696)
at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:552)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161)
at com.example.ej10.MainActivity.onCreate(MainActivity.java:23)
at android.app.Activity.performCreate(Activity.java:7802)
at android.app.Activity.performCreate(Activity.java:7791)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3415)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2022)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:359)
at android.app.ActivityThread.main(ActivityThread.java:7418)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:935)
2020-01-07 20:20:13.706 27052-27052/com.example.ej10 I/Process: Sending signal. PID: 27052 SIG: 9
xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.ej10">
<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=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
main
public class MainActivity extends AppCompatActivity {
private FrameLayout fm1;
private TabLayout tabLayout1;
private PrimerFragment pF = new PrimerFragment();
private SegundoFragment sF= new SegundoFragment();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fm1 = (FrameLayout) findViewById(R.id.fm1);
tabLayout1 = (TabLayout) findViewById(R.id.tabLayout1);
reemplazarFrameLayout(pF);
tabLayout1.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
Fragment fragment = null;
switch (tab.getPosition()) {
case 0:
fragment = pF;
break;
case 1:
fragment = sF;
break;
}
reemplazarFrameLayout(fragment);
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
private void reemplazarFrameLayout(Fragment fragment) {
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.fm1, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.commit();
}
}
I really don't understand the error, I searched the internet but I can't find anything. I don't have any Array so the array error doesn't make sense

My app crashes when execute Intent statement [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
I learn android studio programing and I have problem in my programs,
when I want to go to new activity using intent statement my app crashed,
this is my main activity;
public class MainActivity extends AppCompatActivity {
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
}
public void onStart(){
super.onStart();
FirebaseUser CurrentUser = mAuth.getCurrentUser();
if(CurrentUser == null){
Intent StartIntent = new Intent(MainActivity.this,
StartActivity.class);
startActivity(StartIntent);
finish();
}
}
}
and this is manifest :
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".StartActivity"
android:label="#string/app_name">
</activity>
there is no error message
but thit is what i have into android monitor :
08-23 21:50:33.507 11264-11264/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.ruse.ayse.areyousmartenough, PID: 11264
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ruse.ayse.areyousmartenough/com.ruse.ayse.areyousmartenough.StartActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2378)
at android.app.ActivityThread.access$800(ActivityThread.java:155)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1244)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5433)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.ruse.ayse.areyousmartenough.StartActivity.onCreate(StartActivity.java:31)
at android.app.Activity.performCreate(Activity.java:5301)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2291)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2378) 
at android.app.ActivityThread.access$800(ActivityThread.java:155) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1244) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:136) 
at android.app.ActivityThread.main(ActivityThread.java:5433) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084) 
at dalvik.system.NativeStart.main(Native Method) 
I solved this problem into another project by adding "intent-filter" into manifest file but it does not work with this project,
this is StartActivity :
public class StartActivity extends AppCompatActivity {
private Button mRegBtn ;
private Button mLoginBtn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
mRegBtn = (Button) findViewById(R.id.RegBtn);
mLoginBtn = (Button) findViewById(R.id.LoginBtn);
mRegBtn.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view) {
Intent createAccount = new Intent(StartActivity.this, RegisterActivity.class);
startActivity(createAccount);
}
});
mLoginBtn.setOnClickListener(new View.OnClickListener(){ /////this is line 31
#Override
public void onClick(View view) {
Intent loginAccount = new Intent(StartActivity.this, LoginActivity.class);
startActivity(loginAccount);
}
});
}}

Your problem is at StartActivity.java:31 you are trying to read from a null reference.
By your comment, you look to miss getting the mLoginBtn from your Layout=
mLoginBtn = (Button) findViewById(R.id.btn_login);

Getting error when changing other activity's TextView

I'm a beginner at Android and Java and I have an error when trying to change an other activity's TextView. I've created MainActivity, and another one (PlayerNames).
I've set PlayerNames to be the Launcher activity, maybe the error is that, I don't know. I post the error and the code:
FATAL EXCEPTION: main
Process: com.example.android.mapamundi, PID: 1423
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.mapamundi/com.example.android.mapamundi.PlayerNames}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:68)
at android.support.v7.app.AppCompatDelegateImplV7.<init>(AppCompatDelegateImplV7.java:146)
at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:28)
at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:41)
at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:190)
at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:172)
at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:512)
at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:184)
at com.example.android.mapamundi.PlayerNames.<init>(PlayerNames.java:12)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1606)
at android.app.Instrumentation.newActivity(Instrumentation.java:1066)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2226)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
MAINACTIVITY.JAVA
Well, on MainActivity I only cast the TextViews with public static TextView tv1, so I don't post it
PLAYERNAMES.JAVA
public class PlayerNames extends AppCompatActivity implements View.OnClickListener {
Button accept = (Button) findViewById(R.id.changeNames);
EditText playerInput1 = (EditText) findViewById(R.id.PlayerNameInput1);
EditText playerInput2 = (EditText) findViewById(R.id.PlayerNameInput2);
EditText playerInput3 = (EditText) findViewById(R.id.PlayerNameInput3);
EditText playerInput4 = (EditText) findViewById(R.id.PlayerNameInput4);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_player_names);
accept.setOnClickListener(this);
}
#Override
public void onClick(View view) {
switch (view.getId()){
case (R.id.changeNames):
MainActivity.playerName1.setText(playerInput1.toString());
MainActivity.playerName2.setText(playerInput2.toString());
MainActivity.playerName3.setText(playerInput3.toString());
MainActivity.playerName4.setText(playerInput4.toString());
Intent intent = new Intent(PlayerNames.this, MainActivity.class);
startActivity(intent);
}
}
}
I post AndroidManifest.xml, just in case I have an error or something that causes the error
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:theme="#style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="com.example.android.mapamundi.MainActivity" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity android:name=".PlayerNames">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Can someone please tell me what am I doing wrong? TKS!!

You are calling findViewById() to early, before your activity is fully created. It cannot be in a field initialiser. It has to be in (or after) onCreate(). And also after setContentView(), because you first have to set the content of your activity, before you can try to find views inside of it.

Why does my WebView doesn't work?

Well, I am totally a beginner, I was trying to do some exercise for webview. However, I can't find what problem it is. Can someone helps me? Thanks.
Here is my java class:
public class MainActivity extends AppCompatActivity {
private Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button1)
;
Uri uri = Uri.parse("www.google.com");
final Intent intent = new Intent(Intent.ACTION_VIEW,uri);
button.setOnClickListener(
new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(intent);
}
}
);
}
}
And here is my manifest file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.jinyu.webview">
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Here is my log:
4-16 22:52:03.234 23525-23525/com.example.jinyu.webview E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.jinyu.webview, PID: 23525
android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=www.baidu.com }
at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1798)
at android.app.Instrumentation.execStartActivity(Instrumentation.java:1512)
at android.app.Activity.startActivityForResult(Activity.java:3930)
at android.app.Activity.startActivityForResult(Activity.java:3890)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:820)
at android.app.Activity.startActivity(Activity.java:4213)
at android.app.Activity.startActivity(Activity.java:4181)
at com.example.jinyu.webview.MainActivity$1.onClick(MainActivity.java:29)
at android.view.View.performClick(View.java:5204)
at android.view.View$PerformClick.run(View.java:21153)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
04-16 22:52:04.687 23525-23525/com.example.jinyu.webview I/Process: Sending signal. PID: 23525 SIG: 9

add "http://" or "https://" to your url.

Edit (for future visitors) : add http:// or https:// before actual url.
Shortest way to achieve this is
public class MainActivity extends AppCompatActivity {
private Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(
new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.google.com")));
}
}
);
}
}