Tentativo di richiamare il metodo virtuale 'void android.widget.TextView.setText (java.lang.CharSequence)' su un riferimento oggetto nullo

Question

Impossibile passare i dati da un frammento a un altro utilizzando l'intento. La logica va bene. Si prega di controllare le ultime parti dell'attività principale dove ho inviato stringhe ad altre attività usando putExtra.

Ecco la MainActivity.java:

public class MainActivity extends Activity implements View.OnClickListener { 
EditText ed1,ed2,ed3,ed4,ed5,ed6; 

Button bt1; 
TextView tv1,tv2; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    ed1=(EditText)findViewById(R.id.editText); 
    ed2=(EditText)findViewById(R.id.editText2); 
    ed3=(EditText)findViewById(R.id.editText3); 
    ed4=(EditText)findViewById(R.id.editText4); 
    ed5=(EditText)findViewById(R.id.editText5); 
    ed6=(EditText)findViewById(R.id.editText6); 
    tv1=(TextView)findViewById(R.id.textView); 
    tv2=(TextView)findViewById(R.id.textView2); 
    bt1=(Button)findViewById(R.id.button); 
    bt1.setOnClickListener(this); 
} 
public void onClick(View v) 
{ 

    String str1=ed1.getText().toString(); 
    String str2=ed2.getText().toString(); 
    String str3=ed3.getText().toString(); 
    String str4=ed4.getText().toString(); 
    String str5=ed5.getText().toString(); 
    String str6=ed6.getText().toString(); 

    if(str1.matches("") || str2.matches("") || str3.matches("")) 
    { 
     tv1.setText("One or more fields missing"); 
     if(str4.matches("") || str5.matches("") || str6.matches("")) 
     { 
      tv2.setText("One or more fields missing"); 
     } 
    } 

    else { 
     int age1 = Integer.parseInt(ed2.getText().toString()); 
     int age2 = Integer.parseInt(ed5.getText().toString()); 

     int l1 = str1.length(); 
     str1 = str1.toLowerCase(); 
     str4 = str4.toLowerCase(); 
     int l2 = str4.length(); 

     int[] a = new int[26]; 
     int[] b = new int[26]; 

     for (int i = 0; i < l1; i++) { 

      char c = str1.charAt(i); 
      int x = (int) c - 97; 
      a[x]++; 
     } 
     for (int i = 0; i < l2; i++) { 

      char c = str4.charAt(i); 
      int x = (int) c - 97; 
      b[x]++; 
     } 
     int s=0,p; 
     for(int i=0;i<26;i++) 
     { 
      if(a[i]>b[i]) 
       p=a[i]; 
      else 
       p=b[i]; 

      s+=p; 
     } 
     if(l1>l2) 
      p=l1; 
     else 
      p=l2; 
     double love1=(double)(s/p)*100; 
     double love2=0.0,x; 

     if(age1>age2) { 
      p = age1; 
     x=age2; 
     } 
     else { 
      p = age2; 
      x=age1; 
     } 
     love2=(double)(x/p)*100; 

     Intent in=new Intent(MainActivity.this,SecondActivity.class); 
     String s1=""+love1; 
     String s2=""+love2; 



     in.putExtra("k1",str4); 
     in.putExtra("k2",str4); 
     in.putExtra("k3", love1); 
     in.putExtra("k4",love2); 
     startActivity(in); 
     finish(); 


    } 


} 


} 

Qui è il codice per SecondActivity.java:

public class SecondActivity extends Activity { 

    TextView tv7,tv8,tv9,tv10; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_second); 


    Intent in = getIntent(); 

    String s1 = in.getStringExtra("k1"); 
    String s2 = in.getStringExtra("k2"); 
    String s3 = in.getStringExtra("k3"); 
    String s4 = in.getStringExtra("k4"); 
    tv7=(TextView)findViewById(R.id.textView3); 
    tv8=(TextView)findViewById(R.id.editText4); 
    tv9=(TextView)findViewById(R.id.editText5); 
    tv10=(TextView)findViewById(R.id.editText6); 

    tv7.setText("Hello "+s1); 
    tv8.setText("Your partner "+s2+" is really nice"); 
    tv9.setText("Your love percent based on name is "+s3); 
    tv10.setText("Your love percent based on age is "+s4); 
} 
} 

Qui è l'errore che sto ottenendo:

Process: khurana.nikhil.lovemeter, PID: 4019 
java.lang.RuntimeException: Unable to start activity ComponentInfo{khurana.nikhil.lovemeter/khurana.nikhil.lovemeter.SecondActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325) 
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390) 
     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:5257) 
     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.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference 
     at khurana.nikhil.lovemeter.SecondActivity.onCreate(SecondActivity.java:32) 
     at android.app.Activity.performCreate(Activity.java:5990) 
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) 

Qui è activity_second.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:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin" 
android:paddingBottom="@dimen/activity_vertical_margin" 
android:background="#cefcfd" 
tools:context="khurana.nikhil.lovemeter.SecondActivity"> 


<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="" 
    android:id="@+id/textView3" 
    android:layout_alignParentTop="true" 
    android:layout_centerHorizontal="true" 
    android:layout_marginTop="68dp" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="" 
    android:id="@+id/textView4" 
    android:layout_below="@+id/textView3" 
    android:layout_centerHorizontal="true" 
    android:layout_marginTop="51dp" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="" 
    android:id="@+id/textView5" 
    android:layout_above="@+id/textView6" 
    android:layout_alignStart="@+id/textView6" 
    android:layout_marginBottom="84dp" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="" 
    android:id="@+id/textView6" 
    android:layout_alignParentBottom="true" 
    android:layout_centerHorizontal="true" 
    android:layout_marginBottom="51dp" /> 
</RelativeLayout> 

Answer 1

tv8=(TextView)findViewById(R.id.editText4); 
tv9=(TextView)findViewById(R.id.editText5); 
tv10=(TextView)findViewById(R.id.editText6); 

Modifica questi per:

tv8=(TextView)findViewById(R.id.textView4); 
tv9=(TextView)findViewById(R.id.textView5); 
tv10=(TextView)findViewById(R.id.textView6); 

Hai solo utilizzato l'ID sbagliate di.