App is crashing when trying to switch to new Activity

Question

this is my first question on stackoverflow so don´t judge: :D I am creating a simple android app which is about physics (don´t ask why because I don´t know the answer). So I have created 3 Activites. The Main layout is composed such that there are 2 buttons. One is to get to the activity where there are 3 Newton laws of motion and the other is to get to the activity where there are laws of thermodynamics. Now I have managed to switch from Main activity to Newton activity (I watched a tutorial on youtube) but when I tried to do the same thing with thermodynamics (the code is completely the same) but when I click the button (thermodynamics button) the app crashes. Here is the code:

MainActivity

public class MainActivity extends AppCompatActivity {

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


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }
    else if (id == R.id.action_exit){
        finish();
        return true;
    }

    return super.onOptionsItemSelected(item);
}

public void onGetNewtonLaw(View view)
{
    Intent getNewtonLawIntent = new Intent(this, NewtonScreen.class);

    final int result = 1;

    startActivityForResult(getNewtonLawIntent,result);
}

public void onGetThermodynamicsLaw(View view)
{
    Intent getThermodynamicsLawIntent = new Intent(this, ThermodynamicsScreen.class);

    final int result = 1;

    startActivityForResult(getThermodynamicsLawIntent,result);

}

}

ThermodynamicsScreen Activity

public class ThermodynamicsScreen extends Activity {

 private Button thermodynamicsLawOneButton,  thermodynamicsLawTwoButton,thermodynamicsLawThreeButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.thermodynamics_layout);

    thermodynamicsLawOneButton = (Button) findViewById(R.id.thermodynamics_law_1_button);
    thermodynamicsLawTwoButton = (Button) findViewById(R.id.thermodynamics_law_2_button);
    thermodynamicsLawThreeButton = (Button) findViewById(R.id.thermodynamics_law_3_button);
}

public  void onClickThermodynamicsLawOne(View view)
{
    Toast.makeText(this, "Energy can neither be created nor destroyed; it can only be transferred or changed from one form to another.\n\n ΔE=q+w ",Toast.LENGTH_LONG).show();
}
public void onClickThermodynamicsLawTwo(View view)
{
    Toast.makeText(this, "The entropy of the world only increases and never decreases.", Toast.LENGTH_LONG).show();
}
public void onClickThermodynamicsLawThree(View view)
{
    Toast.makeText(this, "that the entropy of a system approaches a constant value as the temperature approaches absolute zero.", Toast.LENGTH_LONG).show();
}
public void onClickBackToMainMenu (View view)
{
    Intent mainMenu = new Intent();

    setResult(RESULT_OK, mainMenu);

    finish();
}

}

NewtonScreen Activity

public class NewtonScreen extends Activity
{


private Button theAnswerButton, theHintButton, theSuckButton;
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    setContentView(R.layout.newton_layout);

    theAnswerButton = (Button) findViewById(R.id.answer_button);
    theHintButton = (Button) findViewById(R.id.hint_button);
    theSuckButton = (Button)findViewById(R.id.suck_at_physics_button);

}

public void onClickTheAnswerButton(View view)
{

    Toast.makeText(this,
            "An object at rest will remain at rest unless acted on by an unbalanced force. " +
                    "An object in motion continues in motion with the same speed and in the same direction" +
                    " unless acted upon by an unbalanced force.",
            Toast.LENGTH_LONG).show();

}

public  void onClickTheHintButton(View view)
{
    Toast.makeText(this, "F = m*a",Toast.LENGTH_SHORT).show();
}

public  void onClickTheSuckPhysicsButton(View view)
{
    Toast.makeText(this, "For every action there is an equal and opposite re-action.", Toast.LENGTH_LONG).show();
}

public void onClickBackToMainMenu (View view)
{
    Intent mainMenu = new Intent();

    setResult(RESULT_OK, mainMenu);

    finish();
}

}

E/AndroidRuntime﹕ FATAL EXCEPTION: main

Log (everything that was red)

       Process: com.example.android.newtonsfirstlawofmotion, PID: 8432
       java.lang.IllegalStateException: Could not execute method of the activity
        at android.view.View$1.onClick(View.java:3827)
        at android.view.View.performClick(View.java:4442)
        at android.view.View$PerformClick.run(View.java:18473)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5105)
        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:792)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at android.view.View$1.onClick(View.java:3822)

            

at android.view.View.performClick(View.java:4442)
            at android.view.View$PerformClick.run(View.java:18473)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5105)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.android.newtonsfirstlawofmotion/com.example.android.newtonsfirstlawofmotion.ThermodynamicsScreen}; have you declared this activity in your AndroidManifest.xml?
            at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1628)
            at android.app.Instrumentation.execStartActivity(Instrumentation.java:1424)
            at android.app.Activity.startActivityForResult(Activity.java:3468)
            at android.app.Activity.startActivityForResult(Activity.java:3429)
            at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:748)
            at com.example.android.newtonsfirstlawofmotion.MainActivity.onGetThermodynamicsLaw(MainActivity.java:63)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at android.view.View$1.onClick(View.java:3822)
            at android.view.View.performClick(View.java:4442)
            at android.view.View$PerformClick.run(View.java:18473)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5105)
            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:792)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
            at dalvik.system.NativeStart.main(Native Method)

Thanks for your response in advance! :)

Answer 1

The key line of the error is this one:

android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.android.newtonsfirstlawofmotion/com.example.android.newtonsfirstlawofmotion.ThermodynamicsScreen}; have you declared this activity in your AndroidManifest.xml?

It looks like you forgot to declare the ThermodynamicsScreen Activity in your AndroidManifest.xml file. Open up that file and declare your ThermodynamicsScreen Activity. It should look similar to this:

<activity
    android:name=".ThermodynamicsScreen"
    android:label="@string/your_title_string"
    android:parentActivityName=".MainActivity"
    android:theme="@style/AppTheme.NoActionBar">
    <meta-data
        android:name="android.support.PARENT_ACTIVITY"
        android:value=".MainActivity" />
</activity>

Answer 2

Thanks guys I found the error myself when searching through the log (I would not find it if you did not recommend me that). The problem was that I did not declared the thermodynamics activity in the manifest. It is working now. There is no better feeling than this hahaha :)

Answer 3

This line is the problem:

   Intent mainMenu = new Intent();

Pass required parameters to the

Intent

constructor like you've done in the other two classes.

It should be

  Intent mainMenu = new Intent(this, NewtonScreen.class);