如何将数组列表转换为数组？

Question

我有一个包含 JSON 个值的数组列表。我想把它转换成一个数组，然后我将它发送给MapActivity。我试了很多方法都失败了

for (int i = 0; i < matchFixture.length(); i++) 
{
    JSONObject c = matchFixture.getJSONObject(i);
    String matchId = c.getString(TAG_MATCHID);
    Log.d("matchId", matchId);

    //  hashmap for single match
    HashMap<String, String> matchFixture = new HashMap<String, String>();

    // adding each child node to HashMap key => value
    matchFixture.put(TAG_MATCHID, matchId);

    matchFixtureList.add(matchFixture);

    //item=matchFixtureList.get(0).toString();
    String[] stockArr = matchFixtureList.toArray(new String[matchFixtureList.size()]);
    stockArr = matchFixtureList.toArray(stockArr);
    for(String s : stockArr)
        System.out.println(s);
}

Answer 1

更改以下行

String[] stockArr = matchFixtureList.toArray(new String[matchFixtureList.size()]);
stockArr = matchFixtureList.toArray(stockArr);

到

String[] stockArr = new String[matchFixtureList.size()];
stockArr = matchFixtureList.toArray(stockArr);

错误是您在数组初始化期间转换为数组，而这根本不需要。

Answer 2

您正在尝试将 HashMap 类型转换为 String 您的地图是 -

 //  hashmap for single match
    HashMap<String, String> matchFixture = new HashMap<String, String>();
    // adding each child node to HashMap key => value
    matchFixture.put(TAG_MATCHID, matchId);

并且您正在将 matchFixture（这是一个映射）添加到 ArrayList（应该是 HashMap 列表）

matchFixtureList.add(matchFixture);

现在，如果你想将 matchFixtureList 转换为数组，那么你应该这样做 -

    HashMap<String,String>[] stockArr = new HashMap[matchFixtureList.size()];
    stockArr = matchFixtureList.toArray(stockArr);
    for(HashMap<String,String> map : stockArr)
       for(Map.Entry<String,String> entry : map.entrySet()){
           Log.d("debug", entry.getKey() + ","+ entry.getValue());
       }

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