java - 如何对 Android 应用程序的 HashMap 中的数据进行排序？

Question

我试图在 listdataHeader 中按升序对 arr.get() 值进行排序，以便它以以下形式打印出 listDataheader:名称1 1.0名称3 2.0名称5 3.0name2 4.0 等

而不是我预定义的格式

我尝试对 HashMap 进行排序，但当我打开此 Pane 时应用程序崩溃了，listdataheader 如何按随机生成的数组值的升序排列？

package com.example.listview;

import info.androidhive.expandablelistview.R;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.TreeSet;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.ExpandableListView.OnGroupClickListener;
import android.widget.ExpandableListView.OnGroupCollapseListener;
import android.widget.ExpandableListView.OnGroupExpandListener;
import android.widget.Toast;

public class MainActivity extends Activity {

ExpandableListAdapter listAdapter;
ExpandableListView expListView;
List<String> listDataHeader;
HashMap<String, List<String>> listDataChild;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // get the listview
    expListView = (ExpandableListView) findViewById(R.id.lvExp);

    // preparing list data
    prepareListData();

    listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild);

    // setting list adapter
    expListView.setAdapter(listAdapter);

    // Listview Group click listener
    expListView.setOnGroupClickListener(new OnGroupClickListener() {

        @Override
        public boolean onGroupClick(ExpandableListView parent, View v,
                int groupPosition, long id) {
            // Toast.makeText(getApplicationContext(),
            // "Group Clicked " + listDataHeader.get(groupPosition),
            // Toast.LENGTH_SHORT).show();
            return false;
        }
    });

    // Listview Group expanded listener
    expListView.setOnGroupExpandListener(new OnGroupExpandListener() {

        @Override
        public void onGroupExpand(int groupPosition) {
            Toast.makeText(getApplicationContext(),
                    listDataHeader.get(groupPosition),
                    Toast.LENGTH_SHORT).show();
        }
    });

    // Listview Group collasped listener
    /*expListView.setOnGroupCollapseListener(new OnGroupCollapseListener() {

        @Override
        public void onGroupCollapse(int groupPosition) {
            Toast.makeText(getApplicationContext(),
                    listDataHeader.get(groupPosition) + " Collapsed",
                    Toast.LENGTH_SHORT).show();

        }
    });*/

    // Listview on child click listener
    expListView.setOnChildClickListener(new OnChildClickListener() {

        @Override
        public boolean onChildClick(ExpandableListView parent, View v,
                int groupPosition, int childPosition, long id) {
            // TODO Auto-generated method stub
            Toast.makeText(
                    getApplicationContext(),
                    listDataHeader.get(groupPosition)
                            + " : "
                            + listDataChild.get(
                                    listDataHeader.get(groupPosition)).get(
                                    childPosition), Toast.LENGTH_SHORT)
                    .show();
            return false;
        }
    });
}

/*
 * Preparing the list data
 */

String[] stations = {"shell","Esso","Tesco","Asda","BP","Texaco",}; 
private void prepareListData() {
    listDataHeader = new ArrayList<String>();
    listDataChild = new HashMap<String, List<String>>();

        ArrayList<Float> arr   = new ArrayList<Float> ();
        for (int i = 0 ; i <= 12 ; i++)
        {
        arr.add(i, (float) (((Math.random() * 90) + 10)/10)); // add random values to array 
        }


    // Adding child data
    listDataHeader.add("Shell distance: "+ arr.get(0));
    listDataHeader.add("Esso  Distance:" +arr.get(1));
    listDataHeader.add("Tesco Distance "+arr.get(2));
    listDataHeader.add("Asda Distance "+arr.get(3));
    listDataHeader.add("BP Distance "+arr.get(4));
    listDataHeader.add("Texaco Distance "+arr.get(5));

    // Adding child data
    List<String> shell = new ArrayList<String>();
    shell.add("Distance: "+arr.get(0));
    shell.add("Fuel price: 141p/litre");
    shell.add("Petrol price: 134p/litre");

    //esso details 
    List<String> esso = new ArrayList<String>();
    esso.add("Distance: "+arr.get(1));
    esso.add("Fuel price: 145p/litre");
    esso.add("Petrol price: 131p/litre");

    //tesco
    List<String> tesco_energy = new ArrayList<String>();
    tesco_energy.add("Distance: "+arr.get(2));
    tesco_energy.add("Fuel price: 144p/litre");
    tesco_energy.add("Petrol price: 139p/litre");

    //asda
    List<String> asda = new ArrayList<String>();
    asda.add("Distance: "+arr.get(3));
    asda.add("Fuel price: 139p/litre");
    asda.add("Petrol price: 131p/litre");

    //bp
    List<String> bp = new ArrayList<String>();
    bp.add("Distance: "+arr.get(4));
    bp.add("Fuel price: 144p/litre");
    bp.add("Petrol price: 139p/litre");

    //texaco
    List<String> texaco = new ArrayList<String>();
    texaco.add("Distance: "+arr.get(5));
    texaco.add("Fuel price: 144p/litre");
    texaco.add("Petrol price: 139p/litre");

    listDataChild.put(listDataHeader.get(0), shell); // Header, Child data
    listDataChild.put(listDataHeader.get(1), esso);
    listDataChild.put(listDataHeader.get(2), tesco_energy);
    listDataChild.put(listDataHeader.get(3), asda);
    listDataChild.put(listDataHeader.get(4), bp);
    listDataChild.put(listDataHeader.get(5), texaco);

    /*HashMap<String, Double> sorted = new HashMap<String, Double>();
    sorted = sortHashMap((HashMap<String, Double>) listDataHeader);
    for (String cityName : sorted.keySet()){
        System.out.println(cityName + " " + sorted.get(cityName));
    }*/
}

//sort map
private HashMap<String, Double> sortHashMap(HashMap<String, Double> input){
    Map<String, Double> tempMap = new HashMap<String, Double>();
    for (String wsState : input.keySet()){
        tempMap.put(wsState,input.get(wsState));
    }

    List<String> mapKeys = new ArrayList<String>(tempMap.keySet());
    List<Double> mapValues = new ArrayList<Double>(tempMap.values());
    HashMap<String, Double> sortedMap = new LinkedHashMap<String, Double>();
    TreeSet<Double> sortedSet = new TreeSet<Double>(mapValues);
    Object[] sortedArray = sortedSet.toArray();
    int size = sortedArray.length;
    for (int i=0; i<size; i++){
        sortedMap.put(mapKeys.get(mapValues.indexOf(sortedArray[i])), 
                      (Double)sortedArray[i]);
    }
    return sortedMap;
}

}

Answer 1

我猜你想按值排序。在这种情况下，你可以这样做:

public Map<String, Double> sortMap(Map<String, Double> unsortMap) {

    List<Map.Entry<String, Double>> list = new LinkedList<Entry<String, Double>>(
            unsortMap.entrySet());

    // sort list based on comparator
    Collections.sort(list, new Comparator<Object>() {
        @SuppressWarnings("unchecked")
        public int compare(Object o1, Object o2) {
            return ((Map.Entry<String, Double>) o1).getValue().compareTo(
                    ((Map.Entry<String, Double>) o2).getValue());
        }
    });

    // put sorted list into map again
    Map<String, Double> sortedMap = new LinkedHashMap<String, Double>();
    for (Iterator<Entry<String, Double>> it = list.iterator(); it.hasNext();) {
        Map.Entry<String, Double> entry = it.next();
        sortedMap.put(entry.getKey(), entry.getValue());
    }
    return sortedMap;
}

但是，如果您想按键更改排序:

    return ((Map.Entry<String, Double>) o1).getValue().compareTo(
                    ((Map.Entry<String, Double>) o2).getValue());

到

     return ((Map.Entry<String, Double>) o1).getKey().compareTo(
                    ((Map.Entry<String, Double>) o2).getKey());