java.lang.NullPointerException bei ArrayAdapter

Question

Ich habe zwei Layouts, die einen hat editText und die andere als Listview, um die Schriften des editText zu ändern. aber die App wird beim Klicken auf die Schaltfläche zum Öffnen des Layouts mit ListView vermutlich bcuz von Array-Adaptern zerquetscht. Bitte hilf mir. Jeder Button funktioniert einwandfrei. jst Die Schaltfläche btnChangeFont erzeugt ein Problem. Mein Code: MainActivity.java [Bildbeschreibung hier eingeben] [1] Paket com.example.xarn.test;

public class MainActivity extends ActionBarActivity { 

    String[] values = new String[]{ 

      "art_science", 
      "big_bold", 
      "bold_itallic", 
      "crazy_days", 
      "gabriola", 
      "handwritting", 
      "new_bold", 
      "new_itallic", 
      "oldschool", 
      "rough&tough", 
      "sketch", 

    }; 

    ListView listView; 
    EditText text; 
    LinearLayout choosefonts; 
    ImageButton btnOpen, btnClose, btnNew, btnSave, btnDelete,btnChangeFont; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     text = (EditText)findViewById(R.id.text); 
     listView =(ListView)findViewById(R.id.listView); 
     btnChangeFont = (ImageButton)findViewById(R.id.btnChangeFont); 
     btnChangeFont.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       setContentView(R.layout.choosefonts); 
       choosefonts = (LinearLayout)findViewById(R.id.choosefonts); 
       ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,android.R.id.text1,values); 
       listView.setAdapter(adapter); 
       listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
       @Override 
       public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
        switch (position){ 
         case 0:text.setTypeface(Typeface.createFromAsset(getAssets(), "fonts/art_science.ttf")); 
          break; 
         case 1: text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/big_bold.ttf")); 
          break; 
         case 3:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/bold_itallic.ttf")); 
          break; 
         case 4:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/crazy_days.ttf")); 
          break; 
         case 5:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/gabriola.ttf")); 
          break; 
         case 6:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/handwritting.ttf")); 
          break; 
         case 7:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/new_bold.ttf")); 
          break; 
         case 8:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/new_itallic.ttf")); 
          break; 
         case 9:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/oldschool.ttf")); 
          break; 
         case 10:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/rough&tough.ttf")); 
          break; 
         case 11:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/sketch.ttf")); 
          break;} 
       } 
      }); 

      } 
     }); 


     text.setHint("Write Your Note Here............"); 
     text.setTextIsSelectable(true); 

     btnSave = (ImageButton)findViewById(R.id.btnSave); 
     btnSave.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       final Dialog d = new Dialog(MainActivity.this); 
       d.setTitle("Save As"); 
       d.setContentView(R.layout.dialogsave); 
       d.show(); 
       Button btnDialogSave = (Button)d.findViewById(R.id.btnDialogSave); 
       btnDialogSave.setOnClickListener(new View.OnClickListener() { 
        @Override 
        public void onClick(View v) { 
         EditText saveText = (EditText)d.findViewById(R.id.SaveText); 
         try { 
          File myFile = new File("/sdcard/"+saveText.getText()+".txt"); 
          myFile.createNewFile(); 
          FileOutputStream fOut = new FileOutputStream(myFile); 
          OutputStreamWriter myOutWriter = 
            new OutputStreamWriter(fOut); 
          myOutWriter.append(text.getText()); 
          myOutWriter.close(); 
          fOut.close(); 
          Toast.makeText(getBaseContext(), 
            ""+saveText.getText()+" Saved", 
            Toast.LENGTH_SHORT).show(); 
         } catch (Exception e) { 
          Toast.makeText(getBaseContext(), e.getMessage(), 
            Toast.LENGTH_SHORT).show(); 
         } 
         d.dismiss(); 
        } 
       }); 
      } 
     }); 
     btnNew = (ImageButton)findViewById(R.id.btnNew); 
     btnNew.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       text.setText(""); 
      } 
     }); 
     btnClose = (ImageButton)findViewById(R.id.btnClose); 
     btnClose.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       finish(); 
      } 
     }); 
     btnOpen = (ImageButton)findViewById(R.id.btnOpen); 
     btnOpen.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 

       final Dialog d2 = new Dialog(MainActivity.this); 
       d2.setTitle("Open"); 
       d2.setContentView(R.layout.dialogopen); 
       d2.show(); 
       Button btnDialogOpen = (Button)d2.findViewById(R.id.btnDialogOpen); 
       btnDialogOpen.setOnClickListener(new View.OnClickListener() { 
        @Override 
        public void onClick(View v) { 
         EditText openText = (EditText)d2.findViewById(R.id.OpenText); 
         try { 
          File myFile = new File("/sdcard/"+openText.getText()+".txt"); 
          FileInputStream fIn = new FileInputStream(myFile); 
          BufferedReader myReader = new BufferedReader(
            new InputStreamReader(fIn)); 
          String aDataRow = ""; 
          String aBuffer = ""; 
          while ((aDataRow = myReader.readLine()) != null) { 
           aBuffer += aDataRow + "\n"; 
          } 
          text.setText(aBuffer); 
          myReader.close(); 
          Toast.makeText(getBaseContext(), 
            ""+openText.getText()+" Opened", 
            Toast.LENGTH_SHORT).show(); 
         } catch (Exception e) { 
          Toast.makeText(getBaseContext(), e.getMessage(), 
            Toast.LENGTH_SHORT).show(); 
         } 
      d2.dismiss(); 

        } 

       }); 

      } 
     }); 

    } 



    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return 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(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 

      return true; 
     } else if(id == R.id.changeFont){ 
      final Dialog d3 = new Dialog(MainActivity.this); 
      d3.setContentView(R.layout.choosefonts); 
      d3.setTitle("Choose Fonts"); 
      d3.show(); 
      /* String[] values = new String[]{ 
        "art_science", 
        "big_bold", 
        "bold_itallic", 
        "crazy_days", 
        "gabriola", 
        "handwritting", 
        "new_bold", 
        "new_itallic", 
        "oldschool", 
        "rough&tough", 
        "sketch", 

      }; 
      ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,android.R.id.text1,values); 
      listView.setAdapter(adapter); 
      listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
       @Override 
       public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
        switch (position){case 0:text.setTypeface(Typeface.createFromAsset(getAssets(), "fonts/art_science.ttf")); 
         // text.setTypeface(Typeface.createFromAsset(getAssets(), "fonts/art_science.ttf")); 
         break; 
         case 1: text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/big_bold.ttf")); 
          break; 
         case 3:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/bold_itallic.ttf")); 
          break; 
         case 4:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/crazy_days.ttf")); 
          break; 
         case 5:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/gabriola.ttf")); 
          break; 
         case 6:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/handwritting.ttf")); 
          break; 
         case 7:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/new_bold.ttf")); 
          break; 
         case 8:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/new_itallic.ttf")); 
          break; 
         case 9:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/oldschool.ttf")); 
          break; 
         case 10:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/rough&tough.ttf")); 
          break; 
         case 11:text.setTypeface(Typeface.createFromAsset(getAssets(),"fonts/sketch.ttf")); 
          break;} 
       } 
      });*/ 
     } 


     return super.onOptionsItemSelected(item); 
    } 
} 

xml-Code für das Layout 1:

<RelativeLayout 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/text" 
     android:layout_alignParentTop="true" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentEnd="true" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:height="200pt" 
     android:gravity="top" 
     android:scrollbars="horizontal"/> 

    <ImageButton 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/btnNew" 
     android:layout_below="@+id/text" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:background="@drawable/new1" /> 

    <ImageButton 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/btnSave" 
     android:layout_alignBottom="@+id/btnNew" 
     android:layout_toRightOf="@+id/btnNew" 
     android:layout_toEndOf="@+id/btnNew" 
     android:background="@drawable/save" 
     android:clickable="true" /> 


    <ImageButton 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/btnOpen" 
     android:layout_below="@+id/text" 
     android:layout_toRightOf="@+id/btnSave" 
     android:layout_toEndOf="@+id/btnSave" 
     android:background="@drawable/open4"/> 

    <ImageButton 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/btnClose" 
     android:background="@drawable/close" 
     android:layout_below="@+id/text" 
     android:layout_toRightOf="@+id/btnOpen" 
     android:layout_toEndOf="@+id/btnOpen" /> 

    <ImageButton 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/btnDelete" 
     android:background="@drawable/delete" 
     android:layout_below="@+id/text" 
     android:layout_toRightOf="@+id/btnClose" 
     android:layout_toEndOf="@+id/btnClose" /> 

    <ImageButton 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/btnChangeFont" 
     android:layout_alignBottom="@+id/btnDelete" 
     android:layout_below="@+id/text" 
     android:layout_toRightOf="@+id/btnDelete" 
     android:background="@drawable/star"/> 


<RelativeLayout/> 

logcat Fehler

06-22 11:48:18.188 8058-8058/? E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    Process: com.example.xarn.test, PID: 8058 
    java.lang.NullPointerException 
      at com.example.xarn.test.MainActivity$1.onClick(MainActivity.java:65) 
      at android.view.View.performClick(View.java:4443) 
      at android.view.View$PerformClick.run(View.java:18442) 
      at android.os.Handler.handleCallback(Handler.java:733) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:136) 
      at android.app.ActivityThread.main(ActivityThread.java:5021) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:515) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643) 
      at dalvik.system.NativeStart.main(Native Method) 

Answer 1

Ich glaube, Sie Ihre EditText Ansicht zuweisen vergessen haben, an die entsprechende Ansicht in Ihrem XML-Layout genannt "text" .

Answer 2

Die Variable text ist definiert, ihr wird jedoch nie ein Wert zugewiesen.