活動之間的導航無法正常工作

Question

我在我的android應用程序中使用列表視圖。列表視圖工作正常，但是當我嘗試導航到項目單擊另一個活動時，我的應用程序崩潰並在模擬器上顯示消息意外停止您的應用程序。

這裏是我的onItemClick代碼：

public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { 
    // TODO Auto-generated method stub 
    Intent i=new Intent(MainActivity.this,CityActivity.class); 
    i.putExtra("me","hello"); 
    startActivity(i); 
} 

我的第二個活動的代碼：第二個活動的

public class CityActivity extends Activity { 
    TextView text; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.cityname); 
     text= (TextView)findViewById(R.id.textView1); 
     Intent intent = getIntent(); 
     String message=intent.getStringExtra("me"); 
     text.setText(message); 
    } 

    @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; 
    } 
} 

XML代碼：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical" > 

    <TextView 
     android:id="@+id/textView1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="TextView" /> 

</LinearLayout> 

我的第一次的全部代碼活動：

public class MainActivity extends Activity implements OnItemClickListener { 

    ListView listview; 
    List<Country_Name> items; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     listview=(ListView)findViewById(R.id.list); 
     JSONObject main_obj=getjson(); 
     items=new ArrayList<Country_Name>(); 
     try { 
      JSONArray array=main_obj.getJSONArray("Country"); 

      for(int i=0;i<array.length();i++) { 
       JSONObject obj=array.getJSONObject(i); 
       String name=obj.getString("Name"); 
       String image_url=obj.getString("Image"); 
       Country_Name country=new Country_Name(name,image_url); 
       JSONArray array_city=obj.getJSONArray("City"); 
       for(int j=0;j<array_city.length();j++) 
       { 
       JSONObject obj2=array_city.getJSONObject(i); 
       country.items.add(new City_Name(obj2.getString("CName"),obj2.getString("CImage"))); 
       } 
       this.items.add(country); 
      } 
     } 
     catch (JSONException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 

     CustomeBaseAdapter adapter=new CustomeBaseAdapter(this,this.items); 
     this.listview.setAdapter(adapter); 
     listview.setOnItemClickListener(this); 
    } 



    @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; 
    } 

    public JSONObject getjson() { 
     String json=""; 
     StringBuilder builder=new StringBuilder(); 
     JSONObject obj=null; 
     try { 
      BufferedReader reader=new BufferedReader(new InputStreamReader(getAssets().open("Country.txt"))); 

      String line=""; 
      while((line=reader.readLine())!=null) 
      { 
      builder.append(line); 
      } 
      json=builder.toString(); 
      obj=new JSONObject(json); 
     } 
     catch(Exception ex) { 
      ex.toString(); 
     } 

     return obj; 
    } 

    @Override 
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { 
     // TODO Auto-generated method stub 
     Intent i=new Intent(MainActivity.this,CityActivity.class); 
     i.putExtra("me","hello"); 
     startActivity(i); 
     /*Toast toast = Toast.makeText(getApplicationContext(),"hello", 
     Toast.LENGTH_SHORT); 
     toast.show();*/ 
    } 
} 

Answer 1

假設您的「CustomBaseAdapter」類和jSONObject都可以，我應該建議您記錄並調試以檢查它失敗的位置。這似乎是新的活動是好的，所以它的通話失敗可能。你可以嘗試以其他方式使用不同的方式來撥打電話，至少我更喜歡：

public class MainActivity extends Activity { 

    *instead of:* 

    public class MainActivity extends Activity implements OnItemClickListener { 

    *and use "setOnItemClickListener" method instead:* 

    listview.setOnItemClickListener(new OnItemClickListener(){ 
    @Override 
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { 
     // TODO Auto-generated method stub 

    } 

    }); 

希望它可以幫助好運[不幸的是MyApp的已停止