将价值从一个活动传递到另一个活动

Question

I have developed one login form example using soap webservices.

In my app I have a start activity HomePage.HomePage and I have one button(myaccount). When I clicked myaccount button it is redirect to androidloginexampleactivity successfully.

Here I enter the details username and password . The details are correct, it means it is redirected to HomePage with pass the username . I got login is successful but after that it is force closed.

These is the my coding part:

Homepage.java is

public class HomePage extends Activity {
private Button account; 
private TextView tv; 
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);

Button account = (Button) findViewById(R.id.account);
TextView tv = (TextView) findViewById(R.id.textView1);
       tv.setText("Welcome ,"+getIntent().getExtras().getString("username"));

// Listening to register new account link
account.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
       Intent i = new Intent(getApplicationContext() , AndroidLoginExampleActivity.class);
       startActivity(i);
   }
}); 

  }

  }

AndroidLoginExampleActivity.java

  public class AndroidLoginExampleActivity extends Activity {
  private final String NAMESPACE = "http://ws.userlogin.com";
  private final String URL = "http://192.168.1.168:8085/Login/services/Login?wsdl";
  private final String SOAP_ACTION = "http://ws.userlogin.com/authentication";
  private final String METHOD_NAME = "authentication";
  /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Button login = (Button) findViewById(R.id.btn_login);
    login.setOnClickListener(new View.OnClickListener() {

    public void onClick(View arg0) {
    loginAction();

    }
   });
  }

  private void loginAction(){
   SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);

    EditText userName = (EditText) findViewById(R.id.tf_userName);
    String user_Name = userName.getText().toString();
    EditText userPassword = (EditText) findViewById(R.id.tf_password);
    String user_Password = userPassword.getText().toString();

  //Pass value for userName variable of the web service
    PropertyInfo unameProp =new PropertyInfo();
    unameProp.setName("userName");//Define the variable name in the web service method
    unameProp.setValue(user_Name);//set value for userName variable
    unameProp.setType(String.class);//Define the type of the variable
    request.addProperty(unameProp);//Pass properties to the variable

  //Pass value for Password variable of the web service
    PropertyInfo passwordProp =new PropertyInfo();
    passwordProp.setName("password");
    passwordProp.setValue(user_Password);
    passwordProp.setType(String.class);
    request.addProperty(passwordProp);

    SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
    envelope.setOutputSoapObject(request);
    HttpTransportSE androidHttpTransport = new HttpTransportSE(URL);

    try{
        androidHttpTransport.call(SOAP_ACTION, envelope);
           SoapPrimitive response = (SoapPrimitive)envelope.getResponse();
           String status = response.toString();
           TextView result = (TextView) findViewById(R.id.tv_status);
           result.setText(response.toString());

           if(status.equals("Success!"))
            {
               Intent intent = new    Intent(AndroidLoginExampleActivity.this,HomePage.class);
               intent.putExtra("username",userName.getText().toString());
               startActivity(intent);

            }
           else
            {
                // Code for Login failure 
            }
           }



    catch(Exception e){

      }

      }

      }

How can i resolve dis error?

This is my logcat window:

07-17 15:52:00.997: E/AndroidRuntime(1798): FATAL EXCEPTION: main
07-17 15:52:00.997: E/AndroidRuntime(1798): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidlogin.ws/com.androidlogin.ws.HomePage}: java.lang.NullPointerException
.
.
.
dalvik.system.NativeStart.main(Native Method)
 07-17 15:52:00.997: E/AndroidRuntime(1798): Caused by: java.lang.NullPointerException
 07-17 15:52:00.997: E/AndroidRuntime(1798):    at com.androidlogin.ws.HomePage.onCreate(HomePage.java:30)

Answer 1

Just check that your extra is not null:

if(getIntent().getExtras() != null) {
    tv.setText("Welcome ," + getIntent().getExtras().getString("username"));
}

Just add if() condition as I have stated in HomePage.Java

Answer 2

You've to start the AndroidLoginExampleActivity by calling startActivityForResult(Intent, int) instead of startActivity() . That way you may send data to the called activity and receive data from the called activity.

For your reference read - Activity.

Answer 3

Your question: pass value from one activity to another activity + ?

My Answer: You can use SharedPreferences to pass values from one activity to an other.

To set a value:

String inputName = "Peter";
String inputPassword = "I love Stackoverflow";
SharedPreferences prefs = getSharedPreferences("myPrefs", 0);
SharedPreferences editor = prefs.edit();
editor.putString("accountName", inputName);
editor.putString("accountPassword", inputPassword);
editor.commit();

To get inputName and inputPassword in your other activities:

String prefOutputAccountName = "no name";
String prefOutputAccountPassword = "no password";
SharedPreferences prefs = getSharedPreferences("myPrefs", 0);
prefOutputAccountName = prefs.getString("accountName", prefOutputAccountName);
prefOutputAccountPassword = prefs.getString("accountPassword", prefOutputAccountPassword);

I hope i got your question right.

Answer 4

Your question: pass value from one activity to another activity + ?

My Answer: You can use SharedPreferences to pass values from one activity to an other.

To set a value:

String inputName = "Peter";
String inputPassword = "I love Stackoverflow";
SharedPreferences prefs = getSharedPreferences("myPrefs", 0);
SharedPreferences editor = prefs.edit();
editor.putString("accountName", inputName);
editor.putString("accountPassword", inputPassword);
editor.commit();

To get inputName and inputPassword in your other activities:

String prefOutputAccountName = "no name";
String prefOutputAccountPassword = "no password";
SharedPreferences prefs = getSharedPreferences("myPrefs", 0);
prefOutputAccountName = prefs.getString("accountName", prefOutputAccountName);
prefOutputAccountPassword = prefs.getString("accountPassword", prefOutputAccountPassword);

I hope i got your question right.