学步园

MainActivity如下:

package cn.testhashmapsort;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.os.Bundle;
import android.app.Activity;
/**
 * Demo描述:
 * 利用Collections.sort对HashMap里的键值对按照键进行排序
 */
public class MainActivity extends Activity {
    private HashMap<String, Integer> mHashMap;
    private List<Map.Entry<String, Integer>> mHashMapEntryList;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		init();
	}
    private void init(){
    	mHashMap=new HashMap<String, Integer>();
    	mHashMap.put("a", 9527);
    	mHashMap.put("z", 7);
    	mHashMap.put("c", 888);
    	mHashMap.put("x", 666);
    	mHashMapEntryList=new ArrayList<Map.Entry<String,Integer>>(mHashMap.entrySet());
    	
    	System.out.println("-----> 排序前的顺序");
    	for (int i = 0; i < mHashMapEntryList.size(); i++) {
			 System.out.println(mHashMapEntryList.get(i));
		}
    	
    	Collections.sort(mHashMapEntryList, new Comparator<Map.Entry<String,Integer>>() {

			@Override
			public int compare(Map.Entry<String,Integer> firstMapEntry, 
					           Map.Entry<String,Integer> secondMapEntry) {
				return firstMapEntry.getKey().compareTo(secondMapEntry.getKey());
			}
		});
    	
    	System.out.println("-----> 排序后的顺序");
    	for (int i = 0; i < mHashMapEntryList.size(); i++) {
			 System.out.println(mHashMapEntryList.get(i));
		}
    }

}

main.xml如下:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <TextView
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="测试HashMap的排序" 
        android:textSize="20sp"
        />

</RelativeLayout>