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My app is crashing when I try to go to another activity

I'm trying to make a clickable image button redirect to the mainactivity
But since I've putted this code, the app crash when I click on the button to go to the 2nd Activity.
This id the first time I'm making an application.
Activity_good.java
public class Activity_good extends AppCompatActivity {
private Button backGood;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_good);
final TextView txtBien = (TextView) findViewById(R.id.txtBien);
Button genBien = (Button) findViewById(R.id.genBien);
final String[] pBien={"« Pour réussir, votre désir de réussite doit être plus grand que votre peur de l’échec. » Bill Cosby", "trql", "oui", "non"};
genBien.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int rando = (int) (Math.random()*4);
txtBien.setText(pBien[rando]);
}
});
backGood = (Button) findViewById(R.id.backGood);
backGood.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
openMainActivity();
}
});
}
public void openMainActivity(){
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
private Button button1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final MediaPlayer pianoman = MediaPlayer.create(this, R.raw.piano);
button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
pianoman.start();
openActivity_good();
}
});
}
public void openActivity_good() {
Intent intent = new Intent(this, Activity_good.class);
startActivity(intent);
}
}
Crash log ?
E/MediaPlayer: error (1, -19)
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: fr.gab.artapp, PID: 9016
java.lang.RuntimeException: Unable to start activity ComponentInfo{fr.gab.artapp/fr.gab.artapp.Activity_good}: java.lang.ClassCastException: android.support.v7.widget.AppCompatImageButton cannot be cast to android.widget.Button
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
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.ClassCastException: android.support.v7.widget.AppCompatImageButton cannot be cast to android.widget.Button
at fr.gab.artapp.Activity_good.onCreate(Activity_good.java:30)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
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) 
Application terminated.
I exprected to to get back on mainactivity when I click on the button backGood.+

Change this line:
backGood = (Button) findViewById(R.id.backGood);
To this:
backGood = (AppCompatImageButton) findViewById(R.id.backGood);
You are casting a AppCompatImageButton as a Button.

android - MediaRecorder.stop() crashes the app

Everybody,
I'm trying to record audio.
The audio is record perfectly when record button is clicked.
I try to stop the record and the app crashing immediately after the stop button is clicked.
Can you please help me on fixing this code so i could continue building my project.
Here's part of the code:
public class window2 extends AppCompatActivity implements AdapterView.OnItemSelectedListener{
Spinner spinner;//choice between record and Speech-2-text.
Button play,stop,record;//record, stop and replay buttons.
String outputFile;//the record file.
MediaRecorder myAudioRecorder;//the record method.
int reRecord = 0;//reRecord value.
int pathVal = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_window2);
spinner = findViewById(R.id.spinner);
spinner.setOnItemSelectedListener(this);//upon change between record and S2T.
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor edit = sharedPreferences.edit();
if( sharedPreferences.getInt("pathVal",0) == 0)
edit.putInt("pathVal",1);
else {
pathVal = sharedPreferences.getInt("pathVal", pathVal);
edit.putInt("pathVal",pathVal+1);
}
pathVal = sharedPreferences.getInt("pathVal", 0);
edit.commit();
//3 buttons for record,stop and replay.
play = findViewById(R.id.button14);
stop = findViewById(R.id.button13);
record = findViewById(R.id.button11);
//to immune issues that may start if the buttons are enabled.
stop.setEnabled(false);
play.setEnabled(false);
//the file of recording.
outputFile = Environment.getExternalStorageDirectory().getAbsolutePath() + "/"+pathVal+".3gp";
//record settings.
myAudioRecorder = new MediaRecorder();
myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
myAudioRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
myAudioRecorder.setOutputFile(outputFile);
//record button click.
record.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
play.setEnabled(false);
try{
//if we want to re record.
if(reRecord == 1)
{
//we build the settings again.
myAudioRecorder = new MediaRecorder();
myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
myAudioRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
myAudioRecorder.setOutputFile(outputFile);
}
//prepare and start methods.
myAudioRecorder.prepare();
myAudioRecorder.start();
}catch (IllegalStateException ise) {
//something
}catch (IOException ioe){
//something
}
record.setEnabled(false);
stop.setEnabled(true);
Toast.makeText(window2.this, "Recording...", Toast.LENGTH_SHORT).show();
}
});
//stop button click.
stop.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
myAudioRecorder.stop();
myAudioRecorder.reset();
reRecord = 1;
myAudioRecorder = null;
record.setEnabled(true);
stop.setEnabled(false);
play.setEnabled(true);
Toast.makeText(window2.this, "Recorded!", Toast.LENGTH_SHORT).show();
}
});
play.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
MediaPlayer mediaPlayer = new MediaPlayer();
try {
mediaPlayer.setDataSource(outputFile);
mediaPlayer.prepare();
mediaPlayer.start();
Toast.makeText(window2.this, "Playing.", Toast.LENGTH_SHORT).show();
} catch (Exception e){
//something
}
}
});
}
public void OpenWindow4(View view)
{
Spinner spinner = findViewById(R.id.spinner3);
String SpinTxt = spinner.getSelectedItem().toString();
EditText edit2 = findViewById(R.id.editText);
String editTextTxt = edit2.getText().toString();
Intent intent = new Intent(this,window4.class);
intent.putExtra("THE_TEXT",editTextTxt);
intent.putExtra("SPIN_CHOICE",SpinTxt);
startActivity(intent);
}
public void OpenWindow4Speech(View view)
{
Spinner spinner = findViewById(R.id.spinner4);
String SpinTxt = spinner.getSelectedItem().toString();
EditText edit2 = findViewById(R.id.editText2);
String editTextTxt = edit2.getText().toString();
Intent intent = new Intent(this,window4.class);
intent.putExtra("THE_RECORD",outputFile);
intent.putExtra("SPIN_CHOICE",SpinTxt);
intent.putExtra("THE_TEXT",editTextTxt);
startActivity(intent);
}
#Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
String item = adapterView.getItemAtPosition(i).toString();
if (item.equals("S2T"))
{
Intent intent = new Intent(this,windows2B.class);
startActivity(intent);
}
}
#Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
}
and here is the logcat:
01-13 08:42:27.105 1031-1031/com.example.simplenigal.prealphabuilt V/MediaRecorder: prepare
01-13 08:42:27.105 1031-1031/com.example.simplenigal.prealphabuilt V/MediaRecorder: start
01-13 08:42:27.105 1031-1031/com.example.simplenigal.prealphabuilt E/MediaRecorder: start failed: -38
01-13 08:42:27.757 1031-1038/com.example.simplenigal.prealphabuilt I/art: Do partial code cache collection, code=115KB, data=106KB
01-13 08:42:27.757 1031-1038/com.example.simplenigal.prealphabuilt I/art: After code cache collection, code=115KB, data=106KB
01-13 08:42:27.757 1031-1038/com.example.simplenigal.prealphabuilt I/art: Increasing code cache capacity to 512KB
01-13 08:42:27.759 1031-1038/com.example.simplenigal.prealphabuilt I/art: Compiler allocated 6MB to compile void android.view.ViewRootImpl.performTraversals()
01-13 08:42:31.382 1031-1031/com.example.simplenigal.prealphabuilt I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
01-13 08:42:31.452 1031-1031/com.example.simplenigal.prealphabuilt I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
01-13 08:42:31.462 1031-1031/com.example.simplenigal.prealphabuilt V/MediaRecorder: stop
01-13 08:42:31.462 1031-1031/com.example.simplenigal.prealphabuilt E/MediaRecorder: stop called in an invalid state: 0
01-13 08:42:31.463 1031-1031/com.example.simplenigal.prealphabuilt D/AndroidRuntime: Shutting down VM
01-13 08:42:31.468 1031-1031/com.example.simplenigal.prealphabuilt E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.simplenigal.prealphabuilt, PID: 1031
java.lang.IllegalStateException
at android.media.MediaRecorder.native_stop(Native Method)
at android.media.MediaRecorder.stop(MediaRecorder.java:896)
at com.example.simplenigal.prealphabuilt.window2$2.onClick(window2.java:102)
at android.view.View.performClick(View.java:5624)
at android.view.View$PerformClick.run(View.java:22441)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6316)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:872)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)
thanks to every one who paying attention and helping.
Still looking for help

App crashes when Intent is passed

I've MainActivity as following:
public class MainActivity extends AppCompatActivity {
DatabaseHelper myDb;
TextView textView;
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myDb =new DatabaseHelper(this);
Cursor res= myDb.getAllData();
if(res.getCount()==0)
{
textView = (TextView)findViewById(R.id.textView);
textView.setText("No Reminders");
button = (Button)findViewById(R.id.button);
button.setText("Create a Reminder");
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) { //on click 2nd activity is called.
Intent myIntent = new Intent(MainActivity.this, Main2Activity.class);
//myIntent.putExtra("key", value); //Optional parameters
startActivity(myIntent);
}
});
return;
}
StringBuffer buffer=new StringBuffer();
while(res.moveToNext())
{
buffer.append("Id : " +res.getString(0)+"\n");
buffer.append("Event : " +res.getString(1)+"\n");
buffer.append("Location : " +res.getString(2)+"\n");
}
textView = (TextView)findViewById(R.id.textView);
textView.setText(buffer.toString());
}
}
I've another activity named main2activity. But when I press the button in 1st activity, The app crashes and log gives NullPointerException. But this is not duplicate of any other such NullPointerException questions.
Because when I run only my second activity Main2Activity, separately, it does not give to this error. But when It is called from mainActivity, It is giving error. I can't understand why setting listener on button giving NullPointerException.
My Main2Activity is :
public class Main2Activity extends AppCompatActivity {
private static final int PLACE_PICKER_REQUEST = 1;
private TextView mName;
private TextView mAddress;
private TextView mAttributions;
private GoogleApiClient mGoogleApiClient;
public TextView tv4;
private static final LatLngBounds BOUNDS_MOUNTAIN_VIEW = new LatLngBounds(
new LatLng(37.398160, -122.180831), new LatLng(37.430610, -121.972090));
private boolean flag = false;
DatabaseHelper myDb;
EditText newevent;
Button submit;
Button viewremainders;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = getIntent();
setContentView(R.layout.activity_main);
myDb =new DatabaseHelper(this);
newevent=(EditText)findViewById(R.id.newEvent);
submit=(Button)findViewById(R.id.submit);
viewremainders=(Button)findViewById(R.id.view);
Button pickerButton = (Button) findViewById(R.id.pickerButton);
tv4 = (TextView)findViewById(R.id.textView4);
pickerButton.setOnClickListener(new View.OnClickListener() { // <-- Error is here. (NullPointerException.)
#Override
public void onClick(View v) {
try {
PlacePicker.IntentBuilder intentBuilder =
new PlacePicker.IntentBuilder();
intentBuilder.setLatLngBounds(BOUNDS_MOUNTAIN_VIEW);
Intent intent = intentBuilder.build(Main2Activity.this);
startActivityForResult(intent, PLACE_PICKER_REQUEST);
} catch (GooglePlayServicesRepairableException
| GooglePlayServicesNotAvailableException e) {
e.printStackTrace();
}
}
});
AddData();
viewremainders();
}
Here I've mentioned where the error is occurring in comment. And I've other methods with this but only included necessary part.
Thanks in advance!
EDIT:
Log:
08-18 21:48:05.421 29655-29655/com.example.kaushal28.locationbasedreminder E/test: Exception
08-18 21:48:05.424 29655-29655/com.example.kaushal28.locationbasedreminder E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.kaushal28.locationbasedreminder/com.example.kaushal28.locationbasedreminder.Main2Activity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2306)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
at android.app.ActivityThread.access$600(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:5299)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.kaushal28.locationbasedreminder.Main2Activity.onCreate(Main2Activity.java:85)
at android.app.Activity.performCreate(Activity.java:5182)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358) 
at android.app.ActivityThread.access$600(ActivityThread.java:156) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:153) 
at android.app.ActivityThread.main(ActivityThread.java:5299) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
at dalvik.system.NativeStart.main(Native Method) 

You are setting the same layout in both activities. Make sure and add correct layout.
setContentView(R.layout.activity_main);
public class Main2Activity extends AppCompatActivity {
.
.
.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = getIntent();
setContentView(R.layout.activity_main); // here is issue same layout is used for both activity
}
}

ClassCastException android Integer to Long

I was using an integer for the money factor in this little test app but I realized that long was more appropriate and I changed the code so that money is a long instead of an int and I changed SharedPreferences appropriately as well, however it does not work wheras it did when I used int. Thank you for the help!
public class Home extends AppCompatActivity {
SharedPreferences pref;
SharedPreferences.Editor editor;
Intent intent;
TextView home_money_view;
long money; // this is the variable that is causing problems
int initial;
final long TEST = (long)-1;
int gold_pieces;
int gold_price = 50;
TimerTask timerTask;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
home_money_view = (TextView) findViewById(R.id.home_money_view)
pref = getApplicationContext().getSharedPreferences("MY_PREFS", MODE_PRIVATE);
editor = pref.edit();
money = pref.getLong("temp_money",Long.MIN_VALUE); // get value
if (money==Long.MIN_VALUE){
money=0;
}
gold_pieces = pref.getInt("temp_gold",-1);
if (gold_pieces==-1){
gold_pieces=0;
}
initial = pref.getInt("initial",0);
money+=initial;
editor.putInt("initial",0);
editor.commit();
home_money_view = (TextView) findViewById(R.id.home_money_view);
home_money_view.setText(money+"");
editor.commit();
}
public void backToSplash(View view){
intent = new Intent(Home.this,BusinessSelector.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
public void goToSecondView(View view){
long temp_money = money;
editor.putLong("temp_money",temp_money); // set value
int temp_gold = gold_pieces;
editor.putInt("temp_gold",temp_gold);
editor.commit();
intent = new Intent(Home.this,SecondView.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
public void goToOtherView(View view) {
long temp_money = money;
editor.putLong("temp_money",temp_money); // set value
int temp_gold = gold_pieces;
editor.putInt("temp_gold", temp_gold);
editor.commit();
intent = new Intent(Home.this, Next.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
}
Logcat:
04-13 19:01:03.675 12896-12896/com.exampleryancocuzzo.ryan.markettycoon E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.exampleryancocuzzo.ryan.markettycoon/com.exampleryancocuzzo.ryan.markettycoon.Home}: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Long
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Long
at android.app.SharedPreferencesImpl.getLong(SharedPreferencesImpl.java:228)
at com.exampleryancocuzzo.ryan.markettycoon.Home.onCreate(Home.java:56)
at android.app.Activity.performCreate(Activity.java:4466)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
at android.app.ActivityThread.access$600(ActivityThread.java:123) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4424) 
at java.lang.reflect.Method.invokeNative(Native Method) 

Converting String to int from intent

I have 2 activities, and I'm passing edit number editText data to 2nd activity with intent. But in second activity I can't convert data from String to int with any functions. Here is my code:
This is main function:
public class MainActivity extends ActionBarActivity {
public EditText mAge;
public Button mCalculate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAge = (EditText) findViewById(R.id.numberImputEditText);
mCalculate = (Button) findViewById(R.id.calculateButton);
mCalculate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String age = mAge.getText().toString();
Intent mIntent = new Intent(getApplicationContext(),FinalActivity.class);
mIntent.putExtra("age", age);
startActivity(mIntent);
}
});
}
}
and this is 2nd activity where is data passed:
public class FinalActivity extends Activity {
public Button mCalculateAgain;
public TextView mMinAge;
public TextView mMaxAge;
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_final);
Intent mIntent = getIntent();
String age = mIntent.getStringExtra("age");
mCalculateAgain = (Button) findViewById(R.id.calculateAgainButton);
mMinAge = (TextView) findViewById(R.id.minAgeTextView);
mMaxAge = (TextView) findViewById(R.id.maxAgeTextView);
Integer i = Integer.parseInt(age);
mMinAge.setText((i/2)+7);
mMaxAge.setText((i-7)*2);
Toast.makeText(getApplicationContext(), age, Toast.LENGTH_LONG).show();
mCalculateAgain.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent mIntent = new Intent(getApplicationContext(),MainActivity.class);
startActivity(mIntent);
}
});
}
}
here's the log:
`java.lang.RuntimeException: Unable to start activity ComponentInfo{com.robigroza.halfyourage/com.robigroza.halfyourage.FinalActivity}: android.content.res.Resources$NotFoundException: String resource ID #0x12
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2114)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139)
at android.app.ActivityThread.access$700(ActivityThread.java:143)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4960)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x12
at android.content.res.Resources.getText(Resources.java:1058)
at android.widget.TextView.setText(TextView.java:3857)
at com.robigroza.halfyourage.FinalActivity.onCreate(FinalActivity.java:35)
at android.app.Activity.performCreate(Activity.java:5203)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2078)

There's a few types of TextView.setText(...). One takes a CharSequence, which is probably what you expected to use, and another commonly used variant takes an int. The int form expects the parameter to be a resource ID.
mMinAge.setText((i/2)+7);
mMaxAge.setText((i-7)*2);
Given that (i/2)+7 isn't likely to resolve to a string resource, you could do:
mMinAge.setText("" + (i/2)+7);
mMaxAge.setText("" + (i-7)*2);
or better:
mMinAge.setText(String.valueOf((i/2)+7));
mMaxAge.setText(String.valueOf((i-7)*2));

Use this code in MainActivity.java
int age = Integer.parseInt(mage.getText().toString());
Intent i = new Intent(MainActivity.this,FinalActivity.class);
i.putExtra("age", age);
startActivity(i);
Code for FinalActivity .java
Bundle extras = getIntent().getExtras();
int age = extras.getInt("age");
In this way you can send integer value to other activity.
EnJoY coding :)