如何映射两个String []彼此 [英] How to map two String[] to each other

问题描述

我开发一个Android应用程序。我映射两个数组给对方一个HashMap中。我改变这些数组转换成String []的，和他们一同映射。它应该返回值，但它返回null。我不知道我要去哪里错了。我在网上搜索，但我还没有发现任何有用的东西。我的code是如下：

I'm developing an Android app. I'm mapping two arrays to each other with a HashMap. I change these arrays into String[]'s, and map them together. It should return values, but it returns null. I'm not sure where I'm going wrong. I've searched online, but I haven't found anything useful. My code is below:

StationList.java部分

Spinner2.setOnItemSelectedListener(new OnItemSelectedListener() {

        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int arg2, long arg3) {
            // TODO Auto-generated method stub

                String selectedValue = arg0.getItemAtPosition(arg2).toString();

                String[] Yellow_ID = getResources().getStringArray(R.array.Yellow_ID);
                String[] Yellow_Li = getResources().getStringArray(R.array.Yellow_Line);

                Map<String[], String[]> myMap = new HashMap<String[], String[]>();
                    myMap.put(Yellow_Li, Yellow_ID);

                String[] value = myMap.get(selectedValue);
                tv12.setText(String.valueOf (value));




        }

值返回在的TextView 空。我认为这是由于没有值映射到对方。我想AP preciate任何帮助，您可以给我。

Value returns null in the TextView. I think this is due to the values not mapping to each other. I would appreciate any help you could give me.

推荐答案

根据你如何获取你的价值，你希望你的填充时的HashMap做更多的东西像这样

Based on how you're retrieving your value, you want to do something more like this when populating your hashmap

Map<String, String> myMap = new HashMap<String, String>();
for (int i = 0; i < Yellow_Li.length(); i++) {
     myMap.put(Yellow_Li[i], Yellow_ID[i]);
}
String value = myMap.get(selectedValue);

我假设字符串数组的大小相同，所以如果他们不是你应该添加逻辑。

I assume the String arrays are the same size so if they are not you should add that logic in.

此外，如果数组大小都一样，你可以让这样的事情，所以你不必建立一个HashMap：

Also, if the arrays are the same size you could so something like this so you don't have to build a hashmap:

int index = -1;
for (int i = 0; i < Yellow_Li.length(); i++) {
    if (Yellow_Li[i].equals(selectedValue)) {
        index = i;
        break;
    }
}

String value = Yellow_ID[index]; //should do a check for -1 before you try to assign "value"

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