Develop Reference

Button doesn't respond on anything when pressed

What I'm facing is that whenever I press the button to save data to check if the fields is filled up and if it is then it will pass data to back4app but nothing happens even. The Android monitor/Run doesnt even show that the button is being pressed nor the Logcat.
I have a log in activity, register activity, and the main activity. After Logging in it will take you to the main activity which is empty for now but you need to use the navigation bar to take you to this activity and even the fields are filled or not the button does not respond at all. I put a toast to make sure that the button works but the toast doesnt show.
The code below I just copied in the registration form which is the same concept, fill the form test if theres something in there, if not then message will appear then it will send data to back4app. But the button in this problem doesnt work.
This is the button command
package com.example.back4app.userregistrationexample.Classes;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.view.View.OnClickListener;
import com.example.back4app.userregistrationexample.R;
import com.parse.Parse;
import com.parse.ParseObject;
import com.parse.ParseUser;
public class Purchases extends AppCompatActivity {
private EditText establishmentView;
private EditText particularsView;
private EditText amountView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.app_bar_purchases);
establishmentView = (EditText) findViewById(R.id.Edt_Establishment);
particularsView = (EditText) findViewById(R.id.Edt_Particular);
amountView = (EditText) findViewById(R.id.Edt_purchasesnumber);
final Button save = (Button) findViewById(R.id.btn_purchasessave);
save.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
boolean validationError = false;
StringBuilder validationErrorMessage = new StringBuilder("Please, insert ");
if (isEmpty(establishmentView)) {
validationError = true;
validationErrorMessage.append("an Establisment");
}
if (isEmpty(particularsView)) {
if (validationError) {
validationErrorMessage.append(" and ");
}
validationError = true;
validationErrorMessage.append("a Particular");
}
if (isEmpty(amountView)) {
if (validationError) {
validationErrorMessage.append(" and ");
}
validationError = true;
validationErrorMessage.append("a Amount");
}
validationErrorMessage.append(".");
if (validationError) {
Toast.makeText(Purchases.this, validationErrorMessage.toString(), Toast.LENGTH_LONG).show();
return;
}
final ProgressDialog dlg = new ProgressDialog(Purchases.this);
dlg.setTitle("Please, wait a moment.");
dlg.setMessage("Signing up...");
dlg.show();
Toast.makeText(getApplicationContext(),"Data Saved",Toast.LENGTH_SHORT).show();
}
});
}
private boolean isEmpty(EditText text) {
if (text.getText().toString().trim().length() > 0) {
return false;
} else {
return true;
}
}
private boolean isMatching(EditText text1, EditText text2){
if(text1.getText().toString().equals(text2.getText().toString())){
return true;
}
else{
return false;
}
}
private void alertDisplayer(String title,String message){
AlertDialog.Builder builder = new AlertDialog.Builder(Purchases.this)
.setTitle(title)
.setMessage(message)
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
Intent intent = new Intent(Purchases.this, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
ParseUser.logOut();
}
});
AlertDialog ok = builder.create();
ok.show();
}
}
Edit: This is the app_bar_purchases.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">
<TextView
android:id="#+id/txt_puchasesbal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="22dp"
android:text="Balance" />
<EditText
android:id="#+id/Edt_Establishment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="70dp"
android:ems="10"
android:hint="Establishment"
android:inputType="textPersonName" />
<EditText
android:id="#+id/Edt_Particular"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="130dp"
android:ems="10"
android:hint="Particulars"
android:inputType="textPersonName" />
<EditText
android:id="#+id/Edt_purchasesnumber"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="197dp"
android:ems="10"
android:hint="Amount"
android:inputType="number" />
<Button
android:id="#+id/btn_purchasessave"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="178dp"
android:text="Save" />
</RelativeLayout>
Heres what happen when I try to debug it and put break in boolean same thing happens when I put the break in button save it doesnt show anything on the Debug no errors or anything
EDIT I have pasted the right xml file
EDIT Does having RelativeLayout makes the button not respond?
EDIT I have pasted the whole java class
EDIT I also tried deleting everything else on the onClick except for
Toast.makeText(getApplicationContext(),"Data Saved",Toast.LENGTH_SHORT).show(); just to see if the button itself works but it didn't even show the toast

Please check your button id in xml file it's btn_addbalance
then check your id in java file it's btn_purchasessave
please correct this check below code
your line
final Button save = findViewById(R.id.btn_purchasessave);
replace with
final Button save = findViewById(R.id.btn_addbalance);
it will help to you

I took reference of a SO question,
Try using this :
save.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(getBaseContext(), "clicked", Toast.LENGTH_LONG).show();
}
});
And import this
import android.view.View.OnClickListener;
EDIT
Casting most of the android views is reduntant now but it can be the problem, Try to caste the button like this :
final Button save = (Button) findViewById(R.id.btn_purchasessave);
and try your code.
EDIT 2
Try using save.setOnClickListener(this) like this,
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private EditText establishmentView;
private EditText particularsView;
private EditText amountView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
establishmentView = (EditText) findViewById(R.id.Edt_Establishment);
particularsView = (EditText) findViewById(R.id.Edt_Particular);
amountView = (EditText) findViewById(R.id.Edt_purchasesnumber);
final Button save = (Button) findViewById(R.id.btn_purchasessave);
save.setOnClickListener(this);
}
#Override
public void onClick(View v) {
//do things here
}

Display User Input from one activity to another in a textView

I tried to display User Input from my main activity to my second activity, but when I typed in and click the send button on the main activity the whole app just crashes. Please help!
crash solved! Thanks a lot!
However, I can't get the message to display on the second activity.
MainActivity.java
package com.example.dell_inspiron.sendmessage;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import static android.R.id.message;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final String message = getResources().getString(R.string.UserInput);
final Button send = (Button) findViewById(R.id.send);
send.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
Intent sendMessage = new Intent(MainActivity.this, DisplayMessageActivity.class);
sendMessage.putExtra("UserInput", message);
startActivity(sendMessage);
}
});
}
}
activity_main.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:id="#+id/activity_main"
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.example.dell_inspiron.sendmessage.MainActivity">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPersonName"
android:text="#string/edit"
android:ems="10"
android:layout_below="#+id/textView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="15dp"
android:id="#+id/UserInput" />
<Button
android:text="#string/send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/UserInput"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="14dp"
android:id="#+id/send"
android:onClick="sendMessage" />
<TextView
android:text="#string/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/textView"
android:textSize="18sp"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
DisplayMessageActivity.java
package com.example.dell_inspiron.sendmessage;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class DisplayMessageActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
Intent Extra = getIntent();
String textView = Extra.getStringExtra("UserInput");
TextView UserInput = (TextView) findViewById(R.id.UserOutput);
UserInput.setText(textView);
final Button button = (Button) findViewById(R.id.button2);
button.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
launchActivity();
}
});
}
private void launchActivity() {
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
}
}
activity_display_message.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:id="#+id/activity_display_message"
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.example.dell_inspiron.sendmessage.DisplayMessageActivity">
<Button
android:text="#string/Button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="51dp"
android:id="#+id/button2" />
<TextView
android:text="#string/UserOutput"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="91dp"
android:id="#+id/UserOutput" />
<TextView
android:text="#string/enter"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:id="#+id/enter"
android:textSize="18sp"
android:textColor="#android:color/holo_purple" />
</RelativeLayout>

You are passing int, but receive it in String, so your app crashed.
MainActivity
int message = R.string.UserInput;
Intent sendMessage = new Intent(MainActivity.this, DisplayMessageActivity.class);
sendMessage.putExtra("UserInput", message);
DisplayMessageActivity
Bundle Extra = getIntent().getExtras();
String textView = Extra.getString("UserInput");
You should also add
intent.putExtra("UserInput", message);
into launchActivity method.
Solution 1
Change String textView = Extra.getString("UserInput"); to int textView= Extra.getIntExtra("UserInput", 0);
Solution 2
To send the message to your second Activity, you need to use intent inside your MainActivity button click. Modify your code as below.
package com.example.dell_inspiron.sendmessage;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import static android.R.id.message;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String message = getResources().getString(R.string.UserInput);
final Button send = (Button) findViewById(R.id.send);
send.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
Intent sendMessage = new Intent(MainActivity.this,DisplayMessageActivity.class);
sendMessage.putExtra("UserInput", message);
startActivity(sendMessage);
}
});
}
}
Solution 3
This line look wrong to me
final String message = getResources().getString(R.string.UserInput);
If you want to get the editText string, this is the way to go
EditText input = (EditText)findViewById(R.id.UserInput); // declare your editText
final String message = input.getText().toString(); // get your input type

You mentioned that you are getting the user input from the MainActivity but i don't see anything like that in your code but you can do the below to pass some value from one activity to another...
Change your second activity like this
Bundle Extra = getIntent().getExtras();
String textView = Extra.getString("UserInput");
to
Intent Extra = getIntent();
String textView = Extra.getStringExtra("UserInput");
and change your MainActivity like this
int message = R.string.UserInput;
to
String message= getResources().getString(R.string.UserInput);
and
final Button send = (Button) findViewById(R.id.send);
send.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
launchActivity();
}
});
to
Button send = (Button) findViewById(R.id.send);
send.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
startActivity(sendMessage);
}
});

There is issue with your second Activity.You are passing int value in Intents but trying to get String value.
Change it as below:
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class DisplayMessageActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
Bundle Extra = getIntent().getExtras();
int textView = Extra.getInt("UserInput");
TextView UserInput = (TextView) findViewById(R.id.UserInput2);
UserInput.setText(textView);
final Button button = (Button) findViewById(R.id.button2);
button.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
launchActivity();
}
});
}
private void launchActivity() {
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
}
}

not getting any response when clicking on send button in android app

I am an Android newbie and I was following this tutorial for learning android. The app takes input from the user and prints the text whenever the user presses the Submit button. It is able to take input from the user but it does not output anything when Submit button is pressed. Eclipse doesn't show any error in the code, so I don't know what's wrong. Here is the code(Sorry for pasting so much of code as I wasn't able to make out which file was exactly causing the error):
helloworld/src/com.archit.helloworld/DisplayMessageActivity.java
package com.archit.helloworld;
import android.annotation.TargetApi;
import android.app.Activity;
import android.app.Fragment;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.archit.helloworld.R;
public class DisplayMessageActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
// Show the Up button in the action bar.
setupActionBar();
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
//Create new text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
//set the text view as the activity layout
setContentView(textView);
}
/**
* Set up the {#link android.app.ActionBar}, if the API is available.
*/
#TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void setupActionBar() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getActionBar().setDisplayHomeAsUpEnabled(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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() { }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_display_message,
container, false);
return rootView;
}
}
}
helloworld/src/com.archit.helloworld/MainActivity.java
package com.archit.helloworld;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.helloworld.MESSAGE";
#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.main, menu);
return true;
}
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
// Do something in response to button
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
}
}
helloworld/res/layout/activity_display_message.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"
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=".DisplayMessageActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
helloworld/res/layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<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:orientation="horizontal" >
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
helloworld/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.archit.helloworld"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.archit.helloworld.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="com.archit.helloworld.DisplayMessageActivity"
android:label="#string/title_activity_display_message"
android:parentActivityName="com.example.helloworld.MainActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.helloworld.MainActivity" />
</activity>
</application>
</manifest>

/** Called when the user clicks the Send button */
public void sendMessage(View view) {
// Do something in response to button
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
}
has to be
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
// Do something in response to button
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}

Implement onclicklistener Where is your onclickListener

actually you forgot to add startActivity method
public void sendMessage(View view) {
// Do something in response to button
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}

You have missed to call
startActivity(intent);
in your
sendMessage(View V)
method. So finally it will be
public void sendMessage(View view) {
// Do something in response to button
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}

java.lang.IllegalStateException: Could not find a method sendMessage(View)

java code:
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.widget.EditText;
public class MainActivity<View> extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
#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.main, menu);
return true;
}
/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<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:orientation="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
the error message:
06-18 15:19:12.493: E/AndroidRuntime(799): java.lang.IllegalStateException: Could not find a method sendMessage(View) in the activity class com.example.myfirstapp.MainActivity for onClick handler on view class android.widget.Button
I really do not know the reason about that，and i check the case about the method name,that's ok.
Who can help me?

you have to declare your activity as :
public class MainActivity extends Activity {
}
and also you need to declare your button in your onCreate() method like below:
Button button_send= (Button)findViewById(R.id.your_Button_Id);
update:
Also you have to assign an id for your button in your manifest and refer to it above.

Remove <View>. Also move your initialization of Editext to oncreate(). Need not initialize editext evey time on button click.
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
private EdiText editext;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.edit_message);
}
....

How to send text from one Activity to another Activity?

calculated.java: (this has to command to show the calculated.xml layout)
public class Calculated extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.calculated);
}
}
older:
main class:
package com.barth.appie;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.EditText;
public class MainActivity extends Activity {
Button button1;
String text;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
}
public void addListenerOnButton() {
button1 = (Button) findViewById(R.id.buttoncalculate);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
EditText editText = (EditText)findViewById(R.id.editText1);
String text = editText.getText().toString();
Intent myIntent = new Intent(view.getContext(), Calculated.class);
startActivityForResult(myIntent, 0);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
calculated.xml: (this is what it has to show after the button press)
<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" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="42dp"
android:text="#string/text"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
Furthermore I have <string name="text">Value</string> at strings.xml, and in the other class called calculated.class, I have it so that it outputs the calculated.xml ( which works fine)
What I want: I want to display text in calculated.xml, which is a string made in main.class, and i want the string to be the text filled in textfield called "editText1"

import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.EditText;
public class MainActivity extends Activity {
Button button1;
String text;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
}
public void addListenerOnButton() {
button1 = (Button) findViewById(R.id.buttoncalculate);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
EditText editText = (EditText)findViewById(R.id.editText1);
String text = editText.getText().toString();
Intent myIntent = new Intent(view.getContext(),Calculated.class);
myIntent.putExtra("mytext",text);
startActivity(myIntent);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Calculated.java
public class Calculated extends Activity {
TextView mTextview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.calculated);
mTextview = (TextView)findViewById(R.id.textView1);
mTextview.setText(getIntent().getStringExtra("mytext"));
}
calculated.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" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="42dp"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>

To send the data from one activity to another activity
MainActivity.java is first activity from where you want to send data to another activity.
Intent myIntent = new Intent(view.getContext(), Calculated.class);
myIntent.putExtra("text", text);
startActivity(myIntent);
Calculated.java is second activity which receive the intent data whatever you pass from MainActivity.java
String text = myIntent.getStringExtra("text");
TextView textView = (TextView)findViewById(R.id.textView1);
textView.setText(text);