如何将已检查的多个联系人从列表视图发送到android studio

Question

我从手机中检索了联系人，并选择了多个联系人。我需要将选定的联系人发送到android studio.i中的下一个类中，试图发送该数据，但它显示了一个空白页面。如何将选定的联系人显示到下一页。我的主要活动是： package com.example.vijayasrivudanti.contact;

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.provider.ContactsContract;
import android.provider.Settings;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.SparseBooleanArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class ContactDetails extends AppCompatActivity implements View.OnClickListener {
     ListView mainListView;
     Contact[] contact_read;
     Cursor mCursor;
     ArrayAdapter<Contact> listAdapter;
    Button b;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.contact_details);
        b=(Button)findViewById(R.id.done);
        b.setOnClickListener(this);
        mainListView = (ListView) findViewById(R.id.listview);
        mainListView
                .setOnItemClickListener(new AdapterView.OnItemClickListener() {
                    @Override
                    public void onItemClick(AdapterView<?> parent, View item,
                                            int position, long id) {
                        Contact con = listAdapter.getItem(position);
                        con.toggleChecked();
                        ContactViewHolder viewHolder = (ContactViewHolder) item
                                .getTag();
                        viewHolder.getCheckBox().setChecked(con.isChecked());
                    }
                });
        String[] projection = new String[] { ContactsContract.Contacts.HAS_PHONE_NUMBER,
                ContactsContract.Contacts._ID, ContactsContract.Contacts.DISPLAY_NAME };

        mCursor = managedQuery(ContactsContract.Contacts.CONTENT_URI, projection,
                ContactsContract.Contacts.HAS_PHONE_NUMBER + "=?", new String[] { "1" },
                ContactsContract.Contacts.DISPLAY_NAME);

        if (mCursor != null) {
            mCursor.moveToFirst();
            contact_read = new Contact[mCursor.getCount()];

            // Add Contacts to the Array

            int j = 0;
            do {

                contact_read[j] = new Contact(mCursor.getString(mCursor
                        .getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME)));
                j++;
            } while (mCursor.moveToNext());

        } else {
            System.out.println("Cursor is NULL");
        }

        // Add Contact Class to the Arraylist

        ArrayList<Contact> contactList = new ArrayList<Contact>();
        contactList.addAll(Arrays.asList(contact_read));

        // Set our custom array adapter as the ListView's adapter.
        //listAdapter = new ArrayAdapter<Contact>(this,android.R.layout.simple_list_item_multiple_choice,contactList);
        listAdapter = new ContactArrayAdapter(this,contactList);
        mainListView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
        mainListView.setAdapter(listAdapter);
    }

    @Override
    public void onClick(View view) {
        SparseBooleanArray checked = mainListView.getCheckedItemPositions();
        ArrayList<Contact> selectedContacts = new ArrayList<Contact>();
        for(int i = 0;i < checked.size();i++){
            int position = checked.keyAt(i);
            if(checked.valueAt(i))
                selectedContacts .add(listAdapter.getItem(position));

        }
        String[] outputStrArr = new String[selectedContacts.size()];
        for (int i =0;i < selectedContacts.size();i++)
        {
            outputStrArr[i] = String.valueOf(selectedContacts.get(i));

        }

        Intent i = new Intent(ContactDetails.this,Display.class);
        Bundle b = new Bundle();
        b.putStringArray("selectedContacts",outputStrArr);
        i.putExtras(b);
        startActivity(i);

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

    /** Holds Contact data. */
    @SuppressWarnings("unused")
    public static class Contact {
        private String name = "";
        private boolean checked = false;

        public Contact() {
        }

        public Contact(String name) {
            this.name = name;
        }

        public Contact(String name, boolean checked) {
            this.name = name;
            this.checked = checked;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public boolean isChecked() {
            return checked;
        }

        public void setChecked(boolean checked) {
            this.checked = checked;
        }

        public String toString() {
            return name;
        }

        public void toggleChecked() {
            checked = !checked;
        }
    }

    /** Holds child views for one row. */
    @SuppressWarnings("unused")
    private static class ContactViewHolder {
        private CheckBox checkBox;
        private TextView textView;

        public ContactViewHolder() {
        }

        public ContactViewHolder(TextView textView, CheckBox checkBox) {
            this.checkBox = checkBox;
            this.textView = textView;
        }

        public CheckBox getCheckBox() {
            return checkBox;
        }

        public void setCheckBox(CheckBox checkBox) {
            this.checkBox = checkBox;
        }

        public TextView getTextView() {
            return textView;
        }

        public void setTextView(TextView textView) {
            this.textView = textView;
        }
    }

    /** Custom adapter for displaying an array of Contact objects. */
    private static class ContactArrayAdapter extends ArrayAdapter<Contact> {

        private LayoutInflater inflater;

       public ContactArrayAdapter(Context context, List<Contact> contactList) {
            super(context, R.layout.simplerow, R.id.rowTextView, contactList);
            // Cache the LayoutInflate to avoid asking for a new one each time.
            inflater = LayoutInflater.from(context);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // Contact to display
            Contact cont = (Contact) this.getItem(position);
            System.out.println(String.valueOf(position));

            // The child views in each row.
            CheckBox checkBox;
            TextView textView;

            // Create a new row view
            if (convertView == null) {
                convertView = inflater.inflate(R.layout.simplerow, null);

                // Find the child views.
                textView = (TextView) convertView
                        .findViewById(R.id.rowTextView);
                checkBox = (CheckBox) convertView.findViewById(R.id.CheckBox01);

                // Optimization: Tag the row with it's child views, so we don't
                // have to
                // call findViewById() later when we reuse the row.
                convertView.setTag(new ContactViewHolder(textView, checkBox));

                // If CheckBox is toggled, update the Contact it is tagged with.
                checkBox.setOnClickListener(new View.OnClickListener() {
                    public void onClick(View v) {
                        CheckBox cb = (CheckBox) v;
                        Contact contact = (Contact) cb.getTag();
                        contact.setChecked(cb.isChecked());
                    }
                });
            }
            // Reuse existing row view
            else {
                // Because we use a ViewHolder, we avoid having to call
                // findViewById().
                ContactViewHolder viewHolder = (ContactViewHolder) convertView
                        .getTag();
                checkBox = viewHolder.getCheckBox();
                textView = viewHolder.getTextView();
            }

            // Tag the CheckBox with the Contact it is displaying, so that we
            // can
            // access the Contact in onClick() when the CheckBox is toggled.
            checkBox.setTag(cont);

            // Display Contact data
            checkBox.setChecked(cont.isChecked());
            textView.setText(cont.getName());

            return convertView;
        }

    }


    }

我显示所选联系人的下一个布局是：

public class Display extends AppCompatActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_display);
            Bundle b = getIntent().getExtras();
            String[] resultArr = b.getStringArray("selectedContacts");
            ListView lv = (ListView)findViewById(R.id.outputList);
            ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,resultArr);
            lv.setAdapter(adapter);
        }
    }