java - 无法传递 String 和 Int var 来获取数组元素的值？

Question

我被难住了:(我有一个州缩写的字符串数组，除此之外，我还为每个州缩写有一个数组，其中包含许多 id 数字作为字符串。然后我随机选择其中一个州状态数组。

然后，我从所选状态的数组中随机选择一个索引。

这一切都有效，但我不知道如何引用实际的元素/值。

例如:如果我随机选择的状态元素是“PA”并且我随机选择的StateIndex是等于1的int，那么如何将selectedState[selectedStateIndex]值返回给调用方法？

如果我尝试“String id = selectedState[selectedStateIndex]”，则会收到以下错误:Eclipse 中“表达式的类型必须是数组类型，但它解析为字符串”。帮助!几个小时以来一直试图解决这个问题:(

我的代码:

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Random;

public class Scratchpad {


    public static void main(String[] args) {

        String destinationCode;
        String[] states = {"AL", "AZ", "CA", "FL", "IL", "NY", "NC", "PA", "TN", "TX"};

        // TODO - ADD QUOTATION MARKS AROUND ALL THESE STRINGS
        String[] AL = {"10035591", "10035650", "10035664", "10035671", "10035676", "10035682", "10050000", "10050330", "10052160", "10052520", "10052930", "10054176", "10054177", "10054178", "10054179", "10055418", "10055453", "10055455", "10055575", "10730150"};
        String[] AZ = {"30031316", "30031317", "30031318", "30031319", "30050000", "30050014", "30050023", "30050024", "30050025", "30050037", "30050110", "30050190", "30050330", "30050590", "30050924", "30050925", "30130210"};
        String[] CA = {"50010018", "50010020", "50010030", "50010350", "50010540", "50011100", "50011290", "50011450", "50011820", "50012250", "50012350", "50012610", "50012680", "50013080", "50013090", "50013650", "50016650", "50017080", "50017165", "50017841", "50733020"};
        String[] FL = {"100010510", "100010520", "100010530", "100011910", "100013222", "100013223", "100013224", "100013225", "100013226", "100013227", "100013228", "100013229", "100013231", "100013232", "100013233", "100013234", "100013235", "100013236", "100013237", "100014227", "100951160"};
        String[] IL = {"140010017", "140010028", "140012430", "140014322", "140014352", "140014355", "140014490", "140014609", "140014626", "140014638", "140014682", "140014790", "140014804", "140014971", "140015111", "140015112", "140015113", "140015114", "140015115", "140015117", "140310510"};
        String[] NY = {"330010020", "330010490", "330010500", "330011140", "330013050", "330013310", "330013320", "330013360", "330013440", "330014220", "330015000", "330015020", "330015150",  "330015190", "330015327", "330015328", "330015359", "330612010"};
        String[] NC = {"340032022", "340032841", "340050000", "340051390", "340052023", "340052024", "340052025", "340052026", "340052027", "340052028", "340070000", "340071160", "340072029", "340072031", "340072032", "340072033", "340072034", "340072035", "340072036", "340090000", "340630270"};
        String[] PA = {"390010459", "390010759", "390011460", "390012090", "390012300", "390015090", "390017254", "390017255", "390017256", "390017257", "390017258", "390017259", "390017261", "390017262", "390017263", "390017264", "390017266", "390017267", "390017268", "390017271", "391013000"};
        String[] TN = {"430010120", "430010660", "430011200", "430011520", "430011591", "430011592", "430011594", "430030000", "430030760", "430031596", "430031597", "430031598", "430031599", "430050000", "430051601", "430052163", "430052165", "430052193", "431570560"};
        String[] TX = {"440050000", "440050850", "440051850", "440052323", "440053495", "440059391", "440059544", "440059598", "440059599", "440070000", "440070110", "440072520", "440079602", "440079603", "440090000", "440092199", "440093715", "440094205", "440094445", "440094795", "441571440"};


        int randomStateIndex = new Random().nextInt(states.length);
        System.out.println("randomStateIndex = " + randomStateIndex);
        System.out.println("Selected state: " + states[randomStateIndex]);

        String selectedState = states[randomStateIndex];

        int selectedStateIndex = new Random().nextInt(selectedState.length());
        System.out.println(selectedStateIndex);

    }

}

Answer 1

If I try "String id = selectedState[selectedStateIndex]" I get the following error: "The type of the expression must be an array type but it resolved to String" in Eclipse. Help! Been trying to figure this out for hours now : (

正如错误明确指出的那样，selectedState类型为String ;它不是一个数组。方括号与数组类型的变量一起使用。

That all works, but what I can't figure out how to reference the actual element/value.

你需要使用更好的数据结构，这样你才能轻松实现这个目标。我会推荐Map<String, List<String>> 。请参阅以下示例:

Map<String, String[]> statedata = new HashMap<>();
statedata.put("AL", new String[]{"10035591", "10035650", "10035664", "10035671", "10035676", "10035682", "10050000", "10050330", "10052160", "10052520", "10052930", "10054176", "10054177", "10054178", "10054179", "10055418", "10055453", "10055455", "10055575", "10730150"});
stateData.put("AZ", new String[]{"30031316", "30031317", "30031318", "30031319", "30050000", "30050014", "30050023", "30050024", "30050025", "30050037", "30050110", "30050190", "30050330", "30050590", "30050924", "30050925", "30130210"});
...
...
String selectedState = states[randomStateIndex];
statedata.get(selectedState)[selectedStateIndex];