如何将NameValuePair传递给android中的另一个活动？

Question

I have three activities in my application. A -> B -> C

In Activity A : I am getting some data from user and add those data NameValuePair. I do some other operations in Activity B . After that in Activity C , I want to http post NameValuePair. However, I cannot pass NameValuePair one class to another.

I tried this solution: solution

In Activity A :

 ArrayList<NameValuePair> nameValuePairs = new ArrayList<>();
 nameValuePairs.add(new BasicNameValuePair("username", username));
 nameValuePairs.add(new BasicNameValuePair("name", name));

 Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this,Main2Activity.class);
                intent.putParcelableArrayListExtra ("nvp", (ArrayList<? extends Parcelable>) nameValuePairs);
                startActivity(intent);
            }
    });

BasicNameValuePair.java :

public class BasicNameValuePair  implements Parcelable {
    private int mData;

    public int describeContents() {
        return 0;
    }

    public void writeToParcel(Parcel out, int flags) {
        out.writeInt(mData);
    }

    public static final Parcelable.Creator<BasicNameValuePair> CREATOR
            = new Parcelable.Creator<BasicNameValuePair>() {
        public BasicNameValuePair createFromParcel(Parcel in) {
            return new BasicNameValuePair(in);
        }

        public BasicNameValuePair[] newArray(int size) {
            return new BasicNameValuePair[size];
        }
    };

    private BasicNameValuePair(Parcel in) {
        mData = in.readInt();
    }
}

I get an error in my Activity A:

Error:(57, 94) error: incompatible types: ArrayList<NameValuePair> cannot be converted to ArrayList<? extends Parcelable>

How can I pass NameValuePair another activity?

Answer 1

For this problem, you have to make singleton class

that is DataHolder class

    public class DataHolder {

    public static final String TAG = "DataHolder";

    private static DataHolder mDataHolder;

    private ArrayList<NameValuePair> nameValuePairs;


    private DataHolder() {

    }

    /**
     * @return the DataHolder object. (This method returns always same object because of DataHolder is a Singleton Class.)
     */
    public static synchronized DataHolder getInstance() {
        if (null == mDataHolder) {
            mDataHolder = new DataHolder();
        }
        return mDataHolder;
    }


    public ArrayList<NameValuePair> getNameValuePairs() {
        return nameValuePairs;
    }

    public void setNameValuePairs(ArrayList<NameValuePair> nameValuePairs) {
        this.nameValuePairs = nameValuePairs;
    }
}

And then call below code for set the data

ArrayList<NameValuePair> nameValuePairs = new ArrayList<>();
nameValuePairs.add(new BasicNameValuePair("username", username));
nameValuePairs.add(new BasicNameValuePair("name", name));
DataHolder dataHolder = DataHolder.getInstance();
dataHolder.setNameValuePairs(nameValuePairs);

& get data where you want

ArrayList<NameValuePair> nameValuePairs;
DataHolder dataHolder = DataHolder.getInstance();
nameValuePairs = dataHolder.getNameValuePairs();

I hope this will work