Unknown Crashing

Unknown Crashing - java

I am currently trying to develop a simple feature for switching from one page to another but every time I launch the app it crashes.
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Screen One......"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/scan"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click me to another screen" />
</LinearLayout>
MainActivity.java
package com.example.mdpmk1;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addListenerOnButton();
}
public void addListenerOnButton() {
final Context context = this;
button = (Button) findViewById(R.id.scan);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(context, ScanScreen.class);
startActivity(intent);
}
});
}
}
ScanScreen.java
package com.example.mdpmk1;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
public class ScanScreen extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.scan_screen);
}
}
scan_screen.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="You have done it!!"
android:textAppearance="?android:attr/textAppearanceLarge" />
</LinearLayout>
Im quite new to this sort of stuff but i am doing an app for my major at school and would like to have it actually working. Any help would be lovely. Thanks

You forgot to write following statement in your MainActivity's onCreate() method,
setContentView(R.layout.activity_main);
Write here,
public class MainActivity extends Activity
{
Button button;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); // You forgot this line
addListenerOnButton();
}
Also change following line of code,
public void onClick(View arg0)
{
Intent intent = new Intent( MainActivity.this, ScanScreen.class ); // Change here
startActivity(intent);
}

Try editing intent statement in class MainActivity to:
Intent intent = new Intent(MainActivity.this, ScanScreen.class);
startActivity(intent);
You must also add:
setContentView(R.layout.activity_main);
in your ActivityMain class onCreate function to set a view.

setContentView(R.your_layout) doesnt exists in your MainActivity's onCreate(). Try providing your activity a layout.

In your MainActivity onCreate you need to add
setContentView(R.layout.activity_main);

First of all, add SetContentView(R.layout.activity_main) in your MainActivity.OnCreate method befor call to addListenerOnButton.
then be sure that you add your activities entries in your manifest.xml and make MainActivity as your Main Application Activity, like below:
<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=".ScanScreen"/>

Related

Android: StoredPreferences + WebView Link

I'm trying to store the users input from a text field in shared preferences and use that input in a webview link.
Here's what I have so far;
LoginActivity.java
package com.example.app;
import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.content.Intent;
public class LoginActivity extends Activity {
EditText subdomain;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
subdomain = (EditText) findViewById(R.id.subdomain);
Button btn=(Button)findViewById(R.id.sign_in_button);
btn.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Intent myIntent = new Intent(LoginActivity.this,
MainActivity.class);
LoginActivity.this.startActivity(myIntent);
}
});
}
public void saveInfo (View view) {
SharedPreferences sharedPref = getSharedPreferences("spfile",
Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("name", YourSchool.getText().toString());
editor.commit();
}
}
MainActivity.java
package com.example.app;
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class MainActivity extends Activity {
private WebView mWebView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mWebView = (WebView) findViewById(R.id.activity_main_webview);
// Force links and redirects to open in the WebView instead of in a
browser
mWebView.setWebViewClient(new WebViewClient());
// Enable Javascript
WebSettings webSettings = mWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
// Use remote resource
mWebView.loadUrl("https://"+client_subdomain+".domain.co.uk/texts");
// Stop local links and redirects from opening in browser instead
of WebView
mWebView.setWebViewClient(new MyAppWebViewClient());
}
public void displayData (View view) {
SharedPreferences sharedPref = getSharedPreferences("spfile",
Activity.MODE_PRIVATE);
String client_subdomain = sharedPref.getString("name", "");
}
// Prevent the back-button from closing the app
#Override
public void onBackPressed() {
if(mWebView.canGoBack()) {
mWebView.goBack();
} else {
super.onBackPressed();
}
}
#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;
}
return super.onOptionsItemSelected(item);
}
}
activity_login.xml
<LinearLayout
xmlns: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"
android:gravity="center_horizontal"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.app.LoginActivity">
<LinearLayout
android:id="#+id/email_login_form"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<EditText
android:id="#+id/YourSchool"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Your school"
android:maxLines="1"
android:singleLine="true" />
<Button
android:id="#+id/sign_in_button"
style="?android:textAppearanceSmall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:onClick="webView"
android:text="SIGN IN"
android:textStyle="bold" />
</LinearLayout>
</ScrollView>
</LinearLayout>
activity_main.xml
<RelativeLayout
xmlns: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"
tools:context=".MainActivity">
<WebView
android:id="#+id/activity_main_webview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.app">
<uses-permission android:name="android.permission.INTERNET" />
<!-- To auto-complete the email text field in the login form with the
user's emails -->
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.READ_PROFILE" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen">
<activity
android:name=".MainActivity"
android:label="#string/app_name"></activity>
<activity
android:name=".LoginActivity"
android:label="#string/title_activity_login">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER"
/>
</intent-filter>
</activity>
</application>
</manifest>
My problem is that the client_subdomain is flagged as red in the MainActivity.java and when I try to build the project, I get the error: cannot find symbol variable client_subdomain
I think it's probably something small that I've missed out but any help would be greatly appreciated.
Many thanks,
Sam

Its because haven't declared "client_subdomain" as a variable within scope of onCreate
why don't you try changing displayData to
public String displayData () {
SharedPreferences sharedPref = getSharedPreferences("spfile",
Activity.MODE_PRIVATE);
return sharedPref.getString("name", "");
}
and in onCreate of the Main Activity
...
// Enable Javascript
WebSettings webSettings = mWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
// Use remote resource
mWebView.loadUrl("https://"+displayData()+".domain.co.uk/texts");
...
Also, I don't see you ever calling "saveInfo" anywhere in your Login Activity. As well, you should probably change the function too. You aren't grabbing the text from the EditText correctly (whatever YourSchool) is
public void saveInfo() {
SharedPreferences sharedPref = getSharedPreferences("spfile", Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("name", subdomain.getText().toString());
editor.commit();
}
And this will be what your onCreate should have,
protected void onCreate(Bundle savedInstanceState) {
...
btn.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
saveInfo();
Intent myIntent = new Intent(LoginActivity.this, MainActivity.class);
LoginActivity.this.startActivity(myIntent);
}
});
...
}

New Binary XML file line #19: Error inflating class activity

This is my messenger app i'm working on. I've looked around and could not find a problem of the same brand. I disabled and re-enabled the messenger app, and since then it doesn't work. Please, help!
part of the create section
package com.danny4help.gchat;
import android.content.Intent;
import android.inputmethodservice.ExtractEditText;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class GChatCreateActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_gchat_create);
}
public void send(View view){
ExtractEditText eet = (ExtractEditText) findViewById(R.id.eet);
String message = eet.getText().toString();
Intent intent = new Intent(this, GChatReceiveActivity.class);
intent.putExtra(GChatReceiveActivity.EXTRA_MESSAGE,message);
String title = getString(R.string.chooser);
// Intent chosenIntent = Intent.createChooser(intent,title);
startActivity(intent);
}
}
Part of receive section
package com.danny4help.aolcreate;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public class AOLReceive extends AppCompatActivity {
public static final String EXTRA_MESSAGE = "message";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_aolreceive);
Intent intent = getIntent();
String messageSent = intent.getStringExtra(EXTRA_MESSAGE);
TextView messageView = (TextView) findViewById(R.id.message);
messageView.setText(messageSent);
}
}
create xml
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/send"
android:id="#+id/send"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:onClick="sendMessage"/>
<android.inputmethodservice.ExtractEditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/eet"
android:layout_above="#+id/send"
android:layout_centerHorizontal="true"
android:layout_marginBottom="75dp"
android:ems="10"/>
<activity android:name="SendActivity">
<intent-filter>
<action android:name="android.intent.action.SEND"/>
<category android:name="android.intent.category.DEFAULT"/>
<data android:mimeType="text/plain"/>
<data android:mimeType="image/*"/>
</intent-filter>
</activity>
</RelativeLayout>
receive xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns: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"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.danny4help.aolcreate.AOLReceive">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/message"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>

As I catch the error is Inside your Button you have define onClick method name is sendMessage and in java code you are create method send which is not the same as sendMessage. So change your java code to below way.
public void sendMessage(View view){
ExtractEditText eet = (ExtractEditText) findViewById(R.id.eet);
String message = eet.getText().toString();
Intent intent = new Intent(this, GChatReceiveActivity.class);
intent.putExtra(GChatReceiveActivity.EXTRA_MESSAGE,message);
String title = getString(R.string.chooser);
// Intent chosenIntent = Intent.createChooser(intent,title);
startActivity(intent);
}
In Short :
you have to change the method Name as you declare in the xml.

Java in Android from one activity to another activity

I am doing a Android app where I want to show the list of travels contact numbers in a separate screen when clicked on "Travels and Holidays" button. Here is the code:
AppActivity.java
package com.example.android;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class App2Activity extends Activity {
String number=getIntent().getStringExtra("no");
String name=getIntent().getStringExtra("no");
Button button;
Context context = this;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i=new Intent(context,AppActivity.class);
i.putExtra("no","yourno");
i.putExtra("name","yourname");
startActivity(i);
}
});
return;
}
}
App2Activity.java
package com.example.android;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class App2Activity extends Activity {
String number=getIntent().getStringExtra("784568435,438756435,435784365");
String name=getIntent().getStringExtra("Travels1,Travels2,Travels3");
Button button;
Context context = this;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i=new Intent(context,AppActivity.class);
i.putExtra("number","784568435,438756435,435784365");
i.putExtra("name","Travels1,Travels2,Travels3");
startActivity(i);
}
});
return;
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Travels and Holidays" />
</LinearLayout>
strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Travels and Holidays Details</string>
</resources>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mkyong.android"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.CALL_PHONE" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name" >
<activity
android:label="#string/app_name"
android:name=".AppActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:label="#string/app_name"
android:name=".App2Activity" >
</activity>
</application>
</manifest>
What I want is: When I click on "Travels and Holidays" button in the first screen, I want the travels name and contact number to be shown on another screen. When clicked on any travels, it should redirect to the call option of that number.
Where am I going wrong? Please help. Thanks in advance

You need to get your intents inside the onCreate() method. Also, while getting the intent values, you're using the same key "no" both times. You're going to get the same value in both number and name. Do this instead
String number=getIntent().getStringExtra("no");
String name=getIntent().getStringExtra("yourname");
Your onCreate() method inside AppActivity should look like this
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i=new Intent(context,AppActivity.class);
i.putExtra("number","784568435,438756435,435784365");
i.putExtra("name","Travels1,Travels2,Travels3");
startActivity(i);
}
});
return;
}
Then delete the getIntent() code, from above the onCreate() method.

You should only use getIntent() inside onCreate().

In your button listener you have to call the App2Activity, also note a typo in context,App2Activity.class
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i=new Intent(context,App2Activity.class);
// ↑: number 2 missing!!
// note you're harcoding the no and name variables!
i.putExtra("no","yourno");
i.putExtra("name","yourname");
startActivity(i);
}
});
After,
remove the similar code in App2Activity (is not necessary to show content)
make a layout with label or TextView to show the info
in oncreate of App2Activity get the extras
put in this label or textview the extras from the intent
To get extras:
String no = intent.getStringExtra("no");
String name = intent.getStringExtra("name");

You should getIntent() on the Activity's onCreate() method not when initializing the Activity. Because instance variables initialization is actually put in the constructor(s) by the compiler, I think the intent was not initialized in the Constructor.
public class App2Activity extends Activity {
String number;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
number = getIntent().getStringExtra("no");
}
}

How to make a thind link throw a button in a third screen?

two created screens that has two button, each button links to the other, so two screens with two buttons, I don't know how to add a link to the third screen, eclipse was running it but no use
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="I&apos;m screen 1 (main.xml)"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click me to another screen" />
</LinearLayout>
main2.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<Button
android:id="#+id/button2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="(main2.xml) how do get to the 3rd" />
</LinearLayout>
AppActivity.java
package com.mkyong.android;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
public class AppActivity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
addListenerOnButton();
}
public void addListenerOnButton() {
final Context context = this;
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(context, App2Activity.class);
startActivity(intent);
}
});
}
}
App2Activity.java
package com.mkyong.android;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
public class App2Activity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
}
}

package com.mkyong.android;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
public class App2Activity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
button = (Button) findViewById(R.id.button2);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(App2Activity.this, App3Activity.class);
startActivity(intent);
}
});
}
}
Make sure you have registered the App3Activity in AndroidManifest.
EDIT
Here is the complete solution, just copy paste into respective classes
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="I&apos;m screen 1 (main.xml)"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click me to to go second screen" />
</LinearLayout>
main2.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="I&apos;m screen 2 (main2.xml)"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/button2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click me to go to third screen" />
</LinearLayout>
main3.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="I&apos;m screen 3 (main3.xml)"
android:textAppearance="?android:attr/textAppearanceLarge" />
</LinearLayout>
AppActivity
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
public class AppActivity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(AppActivity.this, App2Activity.class);
startActivity(intent);
}
});
}
}
App2Activity
public class App2Activity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
button = (Button) findViewById(R.id.button2);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(App2Activity.this, App3Activity.class);
startActivity(intent);
}
});
}
}
App3Activity
public class AppActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main3);
}
}
AndroidManifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="your_package_name"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="10" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name" >
<activity
android:label="#string/app_name"
android:name=".AppActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".App2Activity" >
</activity>
<activity
android:name=".App3Activity" >
</activity>
</application>
</manifest>

Can I use setContentView outside the oncreate method?

I have seen many people telling that you can set setContentView outside the oncreate method, but I didn't find anywhere an example. Now when I try to use setContentView, my app just crashes. Here is my source code:
AlarmActivity.java:
package com.alarm.example;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.RelativeLayout;
public class AlarmActivity extends Activity{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Button buton = new Button(this);
buton.setId(101);
buton.setText("New alarm");
buton.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT));
RelativeLayout layout1 = new RelativeLayout(this);
layout1.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
layout1.addView(buton);
setContentView(layout1);
Button nou =(Button)findViewById(101);
nou.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
New_ala nou1=new New_ala();
nou1.nou_alarma();
}
});
}
}
New_ala.java:
package com.alarm.example;
public class New_ala extends AlarmActivity{
public void nou_alarma() {
setContentView(R.layout.timepicker);
}
}
TimePicker.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TimePicker
android:id="#+id/timePicker"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<LinearLayout
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_alignParentBottom="true">
<Button
android:id="#+id/picker_save"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Save">
</Button>
<Button
android:id="#+id/picker_cancel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Cancel">
</Button>
</LinearLayout>
</LinearLayout>
On more detail, I can use setContentView(R.layout.timepicker) inside the oncreate method without any problems so the problem is that setContentView isn't working properly inside the New_ala.java class. Can anyone help me?
The code after setting the intent:
AlarmActivity:
package com.alarm.example;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class AlarmActivity extends Activity{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
startActivity(new Intent(this, NewAlarmActivity.class));
}
}
NewAlarmActivity:
package com.alarm.example;
import android.os.Bundle;
public class NewAlarmActivity extends AlarmActivity{
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.timepicker);
}
}

You can call setContentView any time you are running on the event (UI) thread. Be aware that when you do, any fields you initialized by calling findViewById will need to be reset.

The best way to do that is to have multiple activities: instead of nou1.nou_alarma();, create an intent and start a new activity with the new layout.
startActivity(new Intent(this, NewAlarmActivity.class));
And in the onCreate method of NewAlarmActivity, set the content view to R.layout.timepicker

The setContentView() method can be called only once per activity. If you want to completely change the layout at some point you should either go for ViewFlipper or have 2 layouts in the activity and show only one of them at given time by calling view.setVisibility(View.GONE); and view.setVisibility(View.VISIBLE); respectively.

We Keep Coding

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Unknown Crashing - java

Try editing intent statement in class MainActivity to: Intent intent = new Intent(MainActivity.this, ScanScreen.class); startActivity(intent); You must also add: setContentView(R.layout.activity_main); in your ActivityMain class onCreate function to set a view.

setContentView(R.your_layout) doesnt exists in your MainActivity's onCreate(). Try providing your activity a layout.

In your MainActivity onCreate you need to add setContentView(R.layout.activity_main);

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