ListView中的問題，有點意思

問題：
報修歷史出現了三次，我原本是要它出現一次的，望大神解決之！


XML佈局如下：

<?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" >

	<LinearLayout 

  			android:layout_width="fill_parent"

  			android:layout_height="45dp"

  			android:id="@+id/ht_title" 

  			android:background="@drawable/title_bar"

  			android:gravity="center_horizontal|center_vertical"  >  

      		<TextView

        		android:layout_width="wrap_content" 

        		android:layout_height="wrap_content" 

        		android:text="報修歷史"

        		android:textSize="20sp"		

				android:textColor="#ffffff" />       

	</LinearLayout>

    <ListView

        android:layout_below="@id/ht_title"

        android:id="@+id/ht_lv_list"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true">

    </ListView>

    

    <TextView

        android:layout_below="@id/ht_lv_list"

        android:id="@+id/ht_tv_time"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:textSize="15sp">        

    </TextView>

    

    <TextView

        android:layout_below="@id/ht_tv_time"

        android:layout_marginTop="5dp"

        android:id="@+id/ht_tv_category"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:textSize="20sp">

        

    </TextView>

</RelativeLayout>

java 代碼部分：

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;


import com.example.gdin_network_service_system.R;


import android.app.Activity;

import android.os.Bundle;

import android.widget.ArrayAdapter;

import android.widget.ListView;

import android.widget.SimpleAdapter;


public class History extends Activity{


	private ListView lv;


	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_history);

		List<Map<String, String>> datas = new ArrayList<Map<String, String>>();


		putData(datas,"time", "2014/12/23傍晚","category","Mac地址綁定錯誤");

		putData(datas,"time", "2014/12/22中午","category","用戶名或密碼錯誤");


		SimpleAdapter sa = new SimpleAdapter(this, 

				datas, 

				R.layout.activity_history, 

				new String[]{"time","category"},

				new int[]{R.id.ht_tv_time,R.id.ht_tv_category});

		lv = (ListView) findViewById(R.id.ht_lv_list);

		lv.setAdapter(sa);

	}

	private void putData(List<Map<String, String>> datas,String key1,String value1,String key2,String value2){		

		Map<String,String> data = new HashMap<String, String>();		

		data.put(key1,value1);

		data.put(key2,value2);

		datas.add(data);	

	}

}