Question

首先，当我运行程序时，它工作正常，列表元素被发送到微调器....但下次我得到空指针异常 spinner.setAdapter（spinnerArrayAdapter）; 请帮帮我..

   InputStream in = response.getEntity().getContent(); //Get the data in the entity  
                        String a=convertStreamToString(in);  
                        JSONObject jObject  = new JSONObject(a);
                        int result = jObject.getInt("status");
                        final JSONObject banksObj = jObject.getJSONObject("message");
                        ArrayList<String> bankNumbersList =new ArrayList<String>();
                        ArrayList<String> bankNamesList =new ArrayList<String>();

                        Iterator<String> keys = banksObj.keys(); //json is JsonObject From which you get all information
                        while (keys.hasNext()) 
                        {
                         String key = keys.next();
                         Log.d("key",key);
                         bankNumbersList.add(key);

                         try
                         {
                            String bankName = banksObj.getString(key);
                            Log.d("bank",bankName);
                            bankNamesList.add(bankName);
                         }

                         catch (JSONException e)
                         {
                            // Handle Exception
                         }

                        }

                        String[] numbers = new String[bankNumbersList.size()];
                        numbers = bankNumbersList.toArray(numbers);
                        Log.d("numbers",bankNumbersList.toString());
                        String[] names = new String[bankNamesList.size()];
                        names = bankNamesList.toArray(names);
                        Log.d("names",bankNamesList.toString());

                        Spinner spinner = (Spinner) findViewById(R.id.spinner1);
                        Log.d("message","helll");
                        ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(Registration.this,android.R.layout.simple_spinner_item, bankNamesList); 
                        //You can create Spinner for Numbers just change numbers

                        spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

                        if (!bankNamesList.equals(""))

                           spinner.setAdapter(spinnerArrayAdapter);


                        if(result==1)
                        {
                            Log.d("message","hellllllllllo");
                            runOnUiThread(new Runnable() {

                                @Override
                                public void run() {
                                    // TODO Auto-generated method stub
//                                  Log.d("banks",banks);

                                    Toast.makeText( Registration.this, "Success", Toast.LENGTH_LONG).show();
                                }
                            });

                        }else if(result==0){
                            runOnUiThread(new Runnable() {

                                @Override
                                public void run() {
                                    // TODO Auto-generated method stub
                                    Toast.makeText( Registration.this, "Unsuccessful",Toast.LENGTH_LONG).show();
                                }
                            });
                        }

                }
             }
            catch(final Exception e){
                Log.d("exception",e.toString());
                runOnUiThread(new Runnable() {

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub

                        Toast.makeText( Registration.this, 
                                "Unable to connect. Please try again.++++++++++ ",
                                Toast.LENGTH_LONG).show();

                    }
                });

xml文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ccdddd"  >

    <RelativeLayout
        android:id="@+id/relativeLayout1"
        android:layout_width="fill_parent"
        android:layout_height="70dp"
        android:layout_alignParentLeft="true"
        android:background="#00716f" >

         <TextView
             android:id="@+id/registration"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_centerHorizontal="true"
             android:layout_centerVertical="true"
             android:text="Registration"
             android:textColor="#fff"
             android:textSize="18sp"
             android:textStyle="bold" />

         <ImageView
             android:id="@+id/imageView1"
             android:layout_width="30dp"
             android:layout_height="30dp"
             android:layout_alignParentLeft="true"
             android:layout_centerVertical="true"
             android:layout_marginLeft="24dp"
             android:src="@drawable/backicon" />

</RelativeLayout>

 <ScrollView
        android:id="@+id/scrollview"
        android:layout_width="fill_parent"
        android:layout_height="700dp" 
        android:layout_below="@id/relativeLayout1">



 <Spinner
     android:id="@+id/spinner1"
     android:layout_width="300dp"
     android:layout_height="45dp"
     android:layout_marginTop="19dp"
     android:layout_below="@+id/name"
     android:layout_centerHorizontal="true" />

    </RelativeLayout>
   </ScrollView>

</RelativeLayout>

Answer 1

要从Json获取所有键和值，您可以使用以下代码

ArrayList alKeys=new ArrayList();
ArrayList alValues=new ArrayList();


Iterator<String> iter = json.keys();
while (iter.hasNext()) {
    String key = iter.next();
    alKeys.add(key);
    try {
        String value = json.getString(key);
        alValues.add(value);
    } catch (JSONException e) {
        e.printStacktrace();
    }
}

Answer 2

使用keys（）迭代器迭代所有属性，并为每个属性调用get（）。

JSONObject jObject  = new JSONObject(a);
int result = jObject.getInt("status");
final String banks = jObject.getString("message");

ArrayList<String> bankNumbersList =new ArrayList<String>();
ArrayList<String> bankNamesList =new ArrayList<String>();

JSONObject banksObj = jObject.getJSONObject("message");
Iterator<String> iter = banksObj.keys();
while (iter.hasNext()) {
    String key = iter.next();
    bankNumbersList.add(key);
    try {
        String bankName = banksObj.getString(key);
        bankNamesList.add(bankName);
    } catch (JSONException e) {
        // Something went wrong!
    }
}

Answer 3

ArrayList<String> bankNumbers =new ArrayList<String>();
ArrayList<String> bankNames =new ArrayList<String>();

Iterator<String> keys = json.keys(); //json is JsonObject From which you get all information
while (keys.hasNext()) 
{
 String key = keys.next();
 bankNumbers.add(key);

 try
 {
    String bankName = json.getString(key);
    bankNames.add(bankName);
 }

 catch (JSONException e)
 {
    // Handle Exception
 }

}

String[] numbers = new String[bankNumbers.size()];
numbers = bankNumbers.toArray(numbers);

String[] names = new String[bankNames.size()];
names = bankNames.toArray(names);

//在spinner中添加值：

Spinner spinner = (Spinner) findViewById(YOUR_SPINNER_ID);
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item, names); //You can create Spinner for Numbers just change numbers
spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(spinnerArrayAdapter);

是的。

在spinner.setAdapter（spinnerArrayAdapter）获取Null指针异常;

3 个答案: