Develop Reference

Put And Get Extras From Another Class

I have Act_01 (where I put value) and Act_02 (where I get value) but have declared these methods in a Extras class, getting value from Act_02 returns null value:
Act_01: (Where I want to pass the value Name to Act_02)
public class Act_01 extends Activity {
Extras cc_Extras;
Button btn1;
Intent intent;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_01);
cc_Extras = new Extras();
str_Name = "Buck";
btn1 = (Button) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
cc_Extras.putExtras();
startActivity(intent);
}
});
}
}
Act_02: (Where I want ot receive value Name from Act_01 but the app crashes with null value)
public class Act_02 extends Activity {
Extras cc_Extras;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_02);
cc_Extras = new Extras();
if(getIntent() != null && getIntent().getExtras() != null)
{
cc_Extras.getExtras();
}
Toast.makeText(getApplicationContext(), "Name: "+str_Name, Toast.LENGTH_SHORT).show();
}
}
Extras: (Where I define the methods to put and get Extras)
public class Extras extends Activity {
String str_Name;
Intent intent;
public void putExtras() {
// TODO Auto-generated method stub
intent.putExtra("KEY_Name", str_Name);
}
public void getExtras() {
// TODO Auto-generated method stub
str_Name = getIntent().getExtras().getString("KEY_Name");
}
}
EDIT: I do not want to pass and get data directly between activities, I want to use the 3rd class (Extras.java) because I have too many activities having too many values between each other and want to sort of define them globally in Extras so that all my other activities can just call one method instead of getting and putting too many values in my activities.

Your app crashes not with a null value, but a null pointer reference because you created a new Activity manually
cc_Extras = new Extras();
Then called a lifecycle method on it
cc_Extras.getExtras()
Which calls getIntent(), but the Intent was never setup by the Android framework, and cc_Extras.getExtras() wouldn't have any of the data you wanted anyway in the second Activity because it was just created there, not from the first Activity.
Briefly, you should never make a new Activity, and your Extras class does not need to be an Activity in the first place (nor does it provide much benefit).
Just use the Intent object provided by the first Activity to start the second Activity, and get extras like normal. Don't overcomplicate your code. Regarding the title of the question, Intent and Bundle are already "another class" designed by Android for you to transfer data.

On both activities you are creating a new instances of Extras class means they dont hold the same value you can do this to transfer data from A to B
public class Act_01 extends Activity {
Button btn1;
Intent intent;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_01);
str_Name = "Buck";
btn1 = (Button) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
intent = new Intent(Act_01.this, Act_02.class);
intent.putExtra("data", str_Name)
startActivity(intent);
}
});
}
}
And receieve data like this
public class Act_02 extends Activity {
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_02);
// cc_Extras = new Extras();
if(getIntent() != null)
{
if (getIntent().getStringExtra("data") != null) {
Toast.makeText(Act_02.this, "Name: "+getIntent.getStringExtra("data"), Toast.LENGTH_SHORT).show();
}
}
}
}
Also you should consider using Activity Context instead of the application context

Ok! so here are the few things I might wanna suggest you to correct.
Changes needs to be done in the code.
You are not assigning anything to "intent" object , and you have passed a intent without assigning anything to it.
Your instance cc_Extra isn't doing anything in the activity1. You might wanna pass the "intent" object in your constructor of class like cc_Extras= new Extras(intent); and in the Extras class do the following- Intent intent;
Extras(Intent i)
{
this.intent=i;
}
In the activity2 you are creating the new Instance of Extras(). So according to your code it is going to be NULL by default. If you have done the changes from the previous step, you can create new instance by doing cc_Extras(getIntent());
Corrections in the code
1) In Extras class getExtras() method instead of str=getIntent() use str=intent.getExtras.getString().
2) In the activity2 you are not assigning anything to your String str_Name, so you need to return the string you got in getExtras() method. You can do it by changing the return type to String. Below is the sample code.
public String getExtras()
{
str_Name=intent.getExtras().getString("KEY_Name");
//OR
//str_Name=intent.getStringExtra("KEY_Name");
return str_Name;
}
3) By the doing this you need to catch this string in the activity2 by doing `
if(getIntent() != null && getIntent().getExtras() != null)
{
str_Name=cc_Extras.getExtras();
}`
4) Another thing is you must create intent like this-
Intent intent=new Intent(currentActivityName.this,anotherActivity2.class);
//then use the intent object
EDIT- Your code must look like this in the end...
Act1
public class Act_01 extends Activity {
Extras cc_Extras=null;
Button btn1;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_01);
str_Name = "Buck";
btn1 = (Button) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//changes to do
Intent intent= new Intent(Act01.this,Act02.class);
cc_Extras= new Extras(intent);
cc_Extras.putExtras(str_Name);
//end
startActivity(intent);
}
});
}
}
Act02
public class Act_02 extends Activity {
Extras cc_Extras;
String str_Name;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_02);
cc_Extras = new Extras(getIntent());
if(getIntent() != null && getIntent().getExtras() != null)
{
str_Name=cc_Extras.getExtras();
}
Toast.makeText(getApplicationContext(), "Name: "+str_Name, Toast.LENGTH_SHORT).show();
}
}
Extras class
public class Extras { //remove "extends Activity" because it is a class not a activity
String str_Name;
Intent intent;
Extras(Intent i)
{
this.intent=i;
}
public void putExtras(String str) {
// TODO Auto-generated method stub
str_Name=str;
intent.putExtra("KEY_Name", str_Name);
}
public String getExtras() {
// TODO Auto-generated method stub
str_Name = intent.getExtras().getString("KEY_Name");
return str_Name;
}
}
Above code will work just on String. You can extend the functionality if you want.
I hope this must work to get your code working!

Retrieve the data using putExtra [duplicate]

This question already has answers here:
How do I pass data between Activities in Android application?
(53 answers)
Closed 5 years ago.
I am doing admin page. I want to make changes to the data from server. The data already retrieved from server, but I do not know how to data can carry to the next activity(when i click Edit) using putExtra, because I use another java class to for retrieving the information. This is the sample of my table.
Below is my java coding:
public class assessment_table_edit extends AppCompatActivity {
Toolbar toolbar;
String data = "";
TableLayout tlAssessment;
TableRow tr;
TextView stuID,totalmarks,marks,edit;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_assessment_table_edit);
tlAssessment=(TableLayout)findViewById(R.id.tlAssessment_Edit);
final Assessment_Information_GetData getdb=new Assessment_Information_GetData();
new Thread(new Runnable() {
#Override
public void run() {
data =getdb.getDataFromDB();
System.out.println(data);
runOnUiThread(new Runnable() {
#Override
public void run() {
ArrayList<Assessment_Information> users=parseJSON(data);
addData(users);
}
});
}
}).start();
}
View.OnClickListener onClickListener=new View.OnClickListener() {
#Override
public void onClick(View v) {
switch (v.getId()){
case R.id.assessment_id:
Intent iChange=new Intent(assessment_table_edit.this,change_details.class);
//Having problem here
iChange.putExtra();
startActivity(iChange);
break;
}
}
};
Appreciate if some can enlighten me on how to use putExtra or other method to carry the data to another activity.

You can send data using,
Intent iChange = new Intent(assessment_table_edit.this,change_details.class);
iChange.putExtra("YOUR_KEY", "YOUR_VALUE");
startActivity(iChange);
You can get data using,
String data = getIntent().getStringExtra("YOUR_KEY");

You can pass your Object through Intent by using putExtra() method
if you want to pass arraylist then you can use putParcelableArrayListExtra()
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent i = new Intent(this,SecondActivity.class);
ArrayList<Assessment_Information> testing = new ArrayList<Assessment_Information>();
i.putParcelableArrayListExtra("extraextra", testing);
startActivity(i);
}
SecondActivity
public class SecondActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<Assessment_Information> testing = this.getIntent().getParcelableArrayListExtra("extraextra");
}
}

Multiple Instances and Multiple Activities calling the same Activity

I have three Activities. MainActivity,ActivityB and ActivityC. In activity A and B there are two buttons source and destination in both activities. in Activity C there is a list of data. when button is clicked (either Source or destination) from activity A and B. both Activities are calling Activity C
code for Activity A is following
public class MainActivity extends Activity {
TextView source,destination;
Button sendSource,sendDestination,btnTob;
String src,des,activity,checksrc,checkdes;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
source=(TextView)findViewById(R.id.tv_rcvDataA);
destination=(TextView)findViewById(R.id.tv_rcvDataAa);
sendSource=(Button)findViewById(R.id.btn_sendA);
sendDestination=(Button)findViewById(R.id.btn_sendAa);
btnTob=(Button)findViewById(R.id.btn_toB);
sendSource.setText("source");
sendDestination.setText("destination");
src=sendSource.getText().toString();
des=sendDestination.getText().toString();
activity=getClass().getSimpleName();
sendSource.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent send= new Intent(MainActivity.this,ActivityC.class);
send.putExtra("source",src);
send.putExtra("Activity",activity);
startActivity(send);
}
});
sendDestination.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent senda= new Intent(MainActivity.this,ActivityC.class);
senda.putExtra("destination",des);
senda.putExtra("Activity",activity);
startActivity(senda);
}
});
btnTob.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent movetoB= new Intent(MainActivity.this,ActivityB.class);
startActivity(movetoB);
finish();
}
}); }}
and code for Activity B is
public class ActivityB extends Activity {
TextView sourceB,destinationB;
Button sendSourceB,sendDestinationB;
String src,des,activity,checksrc,checkdes;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_b);
sourceB=(TextView)findViewById(R.id.tv_rcvDataB);
destinationB=(TextView)findViewById(R.id.tv_rcvDataBa);
sendSourceB=(Button)findViewById(R.id.btn_sendB);
sendDestinationB=(Button)findViewById(R.id.btn_sendDataBa);
activity=getClass().getSimpleName();
sendDestinationB.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent senda= new Intent(ActivityB.this,ActivityC.class);
senda.putExtra("destination",src);
senda.putExtra("Activity",activity);
startActivity(senda);
}
});
sendSourceB.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent send= new Intent(ActivityB.this,ActivityC.class);
send.putExtra("source",src);
send.putExtra("Activity",activity);
startActivity(send);
}
});}}
now how to check in activityC which activity is calling this activity and which buttonclicklistener is calling the intent

You need to send the value for determine what value and what activity via Intent.putExtra(). Please be remember that you need to set the key as the first parameter for Intent.putExtra(), like
intent.putExtra(THIS_IS_THE_KEY, THIS_IS_YOUR_VALUE);
You need to create something like this:
// This is the key for your putExtra
// you need to create this as global variable.
public static final String FROM_KEY = "FROM";
public static final String ACTIVITY_KEY = "ACTIVITY";
public static final boolean IS_FROM_SOURCE = true;
// This is a sample to send data to Activity C
// where the activity caller is B and from source
Intent senda= new Intent(ActivityB.this,ActivityC.class);
senda.putExtra(FROM_KEY, IS_FROM_SOURCE);
senda.putExtra(ACTIVITY_KEY,"activity_a");
Then in your Activity C, you need to receive the Intent Extra.
You can get the value in Activity onCreate(), something like this:
Bundle extras = getIntent().getExtras();
boolean from = extras.getBoolean(FROM_KEY);
String act = extras.getString(ACTIVITY_KEY);
// do something here if from activity a
if(act.equals("activity_a")) {
if(IS_FROM_SOURCE) {
// do something if from source
} else {
// do something if from destination.
}
} else { // if from activity a
if(IS_FROM_SOURCE) {
// do something if from source
} else {
// do something if from destination.
}
}

In onCreate or anytime after that method is called in Activity-C, you should do the following:
Intent intent = getIntent();
if (intent != null) {
String activity = intent.getStringExtra("Activity");
String src = intent.getStringExtra("source");
// Do something with those values
}

how can i pass my password value into other class of my package

Here i want to send the value of "ourpassword" to say in myclass.java so how can i do this??
public class SetPassword extends Activity{
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.set_password);
final EditText ed=(EditText)findViewById(R.id.setpass);
Button submit=(Button)findViewById(R.id.button1);
submit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String ourpassword=ed.getText().toString();
}
});
}

To pass data between activities use intents.
Intent i= new Intent("com.example.myclass");
i.puExtra("mypassword",ourpassword);
startActivtiy(i);
In myclass
Bundle extras = getIntent().getExtras();
if (extras != null) {
String password = extras.getString("mypassword");
}
You can also pass value to another class by passing value to the constructor of the class
myClass mc= new myClass(ourPassword);
mc.doSomething(); //call some method in another class
In your myclass
class myClass{
String pwd;
public myclass(String password)
{
pwd =password;
}
publidc void doSomething()
{
}
}
Say you want pass value to a class like asynctask
//pass value as a parameter to the class constructor
MyAsyncTask my= new MyAycTask(ourpassword).execute();
In My AsyncTask
class MyAsyncTask extends AsyncTask<Void,Void,Void>
{
public M(String password)//receive value here
{
}
other methods....
}

Create object of this class and get the value as
Define string as static
Object.String;
You can also use Use database. thats better way to store and retrieve passwords

If myclass.java is another Activity class, you can just set the password as a parameter in the intent. For example:
Intent intent = new Intent(getApplicationContext(),myclass.class);
intent.putExtra("password", ourpassword);
startActivity(intent);
... and then you can get the value from within the myclass.java in the onCreate() method like this:
String password = "";
if (getIntent().getStringExtra("password") != null) password = getIntent().getStringExtra("password");
EDIT: You place the Intent code in the onClick() method of the submit button.

Android: starting activity using intent on button click

I'm trying to start activitiy using intent:
public class Bez_provjere_739 extends Activity {
Button Tbutun;
public void onCreate(Bundle savedInstanceState) {
Tbutun.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Intent otvoriIn = new Intent("com.riteh.HL.IN");
startActivity(otvoriIn);
}
});
I use it several times in my aplication in the same way but only in this case i get error:
05-17 00:44:43.694: E/AndroidRuntime(3533): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.riteh.HL/com.riteh.HL.Bez_provjere_739}: java.lang.NullPointerException

You never initialized your button nor assigned to it, so it is null.
Also, there are some basics missing from your code:
// naming conventions - variable names start with lower case letter
private Button tbutun;
#Override
public void onCreate(Bundle savedInstanceState) {
// always call super.onCreate
super.onCreate(savedInstanceState);
// if you have a layout XML, use it
setContentView(R.layout.lay_xml_name);
// if the button declared in the layout, refer to it
tbutun = (Button)findViewById(R.id.the_button_name);
// the rest
}

Initialize your Button, try this
public class Bez_provjere_739 extends Activity {
Button Tbutun;
public void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.main);
Tbutun=(Button)findViewById(R.id.button1) //change the id as per yours
Tbutun.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Intent otvoriIn = new Intent("com.riteh.HL.IN");
startActivity(otvoriIn);
}
});