无法从二维String数组选取随机元素，报错String[]无法转换为int

核心问题修复 #

• 返回类型不匹配：chooseState方法声明返回int，但实际返回的是String[]（二维数组的一行），直接修改方法返回类型为String[]即可。
• 随机元素选取逻辑：Math.random()完全可以用来生成数组的随机索引，通过(int)(Math.random() * 数组长度)得到0到数组长度-1的整数索引，用这个索引就能取出对应位置的元素。另外方法参数里已经传入了Random对象，用它的nextInt方法会更简洁规范。

修正后的代码 #

// multidimensional array
public static final String[][] arrCapitals  =
{   
    { "Alabama", "Montgomery" },        { "Alaska", "Juneau" },
    { "Arizona", "Phoenix" },           { "Arkansas", "Little Rock" },
    { "California", "Sacramento" },     { "Colorado", "Denver" },
    { "Connecticut", "Hartford" },      { "Delaware", "Dover" },
    { "Florida", "Tallahassee" },       { "Georgia", "Atlanta" },
    { "Hawaii", "Honolulu" },           { "Idaho", "Boise" },
    { "Illinois", "Springfield" },      { "Indiana", "Indianapolis" },
    { "Iowa", "Des Moines" },           { "Kansas", "Topeka" },
    { "Kentucky", "Frankfort" },        { "Louisiana", "Baton Rouge" },
    { "Maine", "Augusta" },             { "Maryland", "Annapolis" },
    { "Massachusettes", "Boston" },     { "Michigan", "Lansing" },
    { "Minnesota", "Saint Paul" },      { "Mississippi", "Jackson" },
    { "Missouri", "Jefferson City" },   { "Montana", "Helena" },
    { "Nebraska", "Lincoln" },          { "Nevada", "Carson City" },
    { "New Hampshire", "Concord" },     { "New Jersey", "Trenton" },
    { "New York", "Albany" },           { "New Mexico", "Santa Fe" },
    { "North Carolina", "Raleigh" },    { "North Dakota", "Bismarck" },
    { "Ohio", "Columbus" },             { "Oklahoma", "Oklahoma City" },
    { "Oregon", "Salem" },              { "Pennsylvania", "Harrisburg" },
    { "Rhode Island", "Providence" },   { "South Carolina", "Columbia" },
    { "South Dakota", "Pierre" },       { "Tennessee", "Nashville" },
    { "Texas", "Austin" },              { "Utah", "Salt Lake City" },
    { "Vermont", "Montpelier" },        { "Virginia", "Richmond" },
    { "Washington", "Olympia" },        { "West Virginia", "Charleston" },
    { "Wisconsin", "Madison" },         { "Wyoming", "Cheyenne" }
};

// 修改返回类型为String[]，并使用传入的Random对象生成随机索引
public static String[] chooseState(Random rand, String[][] arrCapitals)
{
    // 生成0到arrCapitals.length-1之间的随机整数索引
    int randomIndex = rand.nextInt(arrCapitals.length);
    // 返回对应索引的州和首府数组
    return arrCapitals[randomIndex];
}

补充说明 #

• 如果仍想使用Math.random()，可以把生成索引的代码改成：

  int randomIndex = (int)(Math.random() * arrCapitals.length);
  

• 调用这个方法时，需要先实例化Random对象，比如：

  Random rand = new Random();
  String[] randomStateCapital = chooseState(rand, arrCapitals);
  System.out.println("随机州：" + randomStateCapital[0] + "，首府：" + randomStateCapital[1]);
  

内容的提问来源于stack exchange，提问作者Ryan Hansen