Illegalstateexception When Click On Button In Android Hello World Program

I'm new to android and I'm trying to implement MyFirstApp given on android google developers site, So app contains one textbox and button, if you enter any text in textfield and cl

Solution 1:

Edit:

Change your Manifest:

<?xml version="1.0" encoding="utf-8"?><manifestxmlns:android="http://schemas.android.com/apk/res/android"package="com.example.myfirstapp"android:versionCode="1"android:versionName="1.0" ><uses-sdkandroid:minSdkVersion="8"android:targetSdkVersion="11" /><applicationandroid:allowBackup="true"android:icon="@drawable/ic_launcher"android:label="@string/app_name"android:theme="@style/AppTheme" ><activityandroid:name=".MainActivity"android:label="@string/title_activity_display_message"><intent-filter ><actionandroid:name="android.intent.action.MAIN" /><categoryandroid:name="android.intent.category.LAUNCHER" /></intent-filter></activity><activityandroid:name=".DisplayMessageActivity" /></application></manifest>

DisplayMessgaeActivity:

publicclassDisplayMessageActivityextendsActivity {

        @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);



        // Get the message from the intentIntentintent= getIntent();
        Stringmessage= intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

        // Create the text viewTextViewtextView=newTextView(this);
        textView.setTextSize(40);
        textView.setText(message);

        // Set the text view as the activity layout
        setContentView(textView);



    }
       }

MainActivity:

publicclassMainActivityextendsActivity {

    publicfinalstaticStringEXTRA_MESSAGE="com.example.myfirstapp.MESSAGE";
  @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_display_message_1);
}

    /** Called when the user clicks the Send button */publicvoidsendMessage() {
        // Do something in response to buttonIntentintent=newIntent(this, DisplayMessageActivity.class);
        EditTexteditText= (EditText) findViewById(R.id.edit_message);
        Stringmessage= editText.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
    }

}

---

your layout should have a life cycle method onCreate It should have a onCreate method and you need to set setContentview(R.layout.yourlayout) for the MainActivity

Solution 2:

You are using two time setContentView(). You can use only one setContentView .

Solution 3:

Your app is looking for the sendMessage() method in an activity where the method is not implimented

java.lang.IllegalStateException:Could not find a method MainActivity.sendMessage(View) in the activity class com.example.myfirstapp.DisplayMessageActivity for onClick handler onview class android.widget.Button</p><p>03-1518:00:03.430: E/AndroidRuntime(592): 

is this the xml layout name activity_display_message_1 where you declare the Button? you must put the method sendMessage also in the same activity

EDIT: FULL SOLUTION

activity_main.xml

<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent" ><Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/button_send"android:onClick="sendMessage" /></LinearLayout>

activity_display_message.xml

<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent" ><EditTextandroid:id="@+id/edit_message"android:layout_weight="1"android:layout_width="0dp"android:layout_height="wrap_content"android:hint="@string/edit_message" /></LinearLayout>

MainActivity

publicclassMainActivityextendsActivity {
publicfinalstaticStringEXTRA_MESSAGE="com.example.myfirstapp.MESSAGE";
    @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
}


    /** Called when the user clicks the Send button */publicvoidsendMessage(View view) {
        // Do something in response to buttonIntentintent=newIntent(this, DisplayMessageActivity.class);
        EditTexteditText= (EditText) findViewById(R.id.edit_message);
        Stringmessage= editText.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
    }
}

DisplayMessageActivity.java

publicclassDisplayMessageActivityextendsActivity {

    @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_message_1);


    // Get the message from the intentIntentintent= getIntent();
    Stringmessage= intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

    // Create the text viewTextViewtextView=newTextView(this);
    textView.setTextSize(40);
    textView.setText(message);
}

}

Update also you manifest file because you've inverse the launcher

<?xml version="1.0" encoding="utf-8"?><manifestxmlns:android="http://schemas.android.com/apk/res/android"package="com.example.myfirstapp"android:versionCode="1"android:versionName="1.0" ><uses-sdkandroid:minSdkVersion="8"android:targetSdkVersion="11" /><applicationandroid:allowBackup="true"android:icon="@drawable/ic_launcher"android:label="@string/app_name"android:theme="@style/AppTheme" ><activityandroid:name=".MainActivity"android:label="@string/title_activity_display_message"><intent-filter ><actionandroid:name="android.intent.action.MAIN" /><categoryandroid:name="android.intent.category.LAUNCHER" /></intent-filter></activity><activityandroid:name=".DisplayMessageActivity" /></application></manifest>

Solution 4:

//Just change your manifest file, its not getting path of your "DisplayMessageActivity" for //sample as below :

 android:name="com.example.checkproject.DisplayMessageActivity"

or

android:name =".DisplayMessageActivity"

Solution 5:

publicvoidsendMessage(View view) {
    // Do something in response to buttonIntentintent=newIntent(this, DisplayMessageActivity.class);
    EditTexteditText= (EditText) findViewById(R.id.edit_message);
    Stringmessage= editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE, message);
    this.startActivity(intent);
}