为什么会这样？（使用数组，增量）

Question

好的，所以我为测验程序制作了数组。虽然一切都很好，但我对这部分感到困惑，以及如何确保我理解发生了什么。

这是点击回答按钮时的代码（我只 post 一个按钮的代码，因为它们都有相同的代码）

questionValueS = Integer.toString(questionValue);
         questionInS = Integer.toString(questionIndex );

               if(questionIndex < Questions.length -1
                )  
{
    if (questionIndex != 5){
        questionsLabel2.setText("");
    } if (questionIndex == 5){
        questionsLabel2.setText(halfQues8);
    }

// make sure the index is in bounds

           questionIndex++ ; // increment the index


         questionValue ++;


         QuestionIndexS.setText(questionInS);
        questionsLabel.setText(Questions[questionIndex]); // set the text to the next question

        /*
         * set the text to the next answer options
         */
        TextButtA.setText(AnswerButtA[questionIndex]);
        TextButtB.setText(AnswerButtB[questionIndex]);
        TextButtC.setText(AnswerButtC[questionIndex]);
        questionNumber.setText("Question " + questionValueS + ".");

       }

            else{

        questionsLabel.setText("Complete");
         questionNumber.setText("");  
         questionsLabel2.setText("");

         TextButtA.setText("");
         TextButtB.setText("");
         TextButtC.setText("");
              Results.setText("Click here for results");
              }

    }

这是代码的另一半

*
  *Icremented Variables
  */

   Integer questionIndex = -1;
   Integer questionValue = 2;
   String questionValueS;
   String questionInS;

          //Non-incremented variable 
           String halfQues8 = "They got upset when he took ____ stuff.";



    /*
     *Questions Array
    */



   String[] Questions = 
    {
        "4 pears were on sale for . How much is each pear?", //Array 0//
    "What is the temperature right below 0 degrees Fahrenheit?", //Array 1//
    "How long it take to reach 60 miles if going 60mph?", //Array 2//
    "How long does it take for Summer to get to the following Summer?", //Array 3
    "What is 100% of 100?", //Array 4//
    " What weighs more. 1 pound of feathers, or 1.01 pounds of thin aluminum foil?", //Array 5//
            "Which word should be on the empty line?", //Array 6 //
            "How many licks does it take to get to the tootsie roll center of a tootsie pop?(No biting)", //Array 7
            "Which statement is true?", //Array 8

    };

   /*
    * Button A
    */
    String[] AnswerButtA = {
        "2.25", //Array 0
    "-1 Celcius",  //Array 1
    "2 hours", //Array 2
    "12 months", //Array 3
    "100", //Array 4
  "1 pound of feathers" , //Array 5//
  "their", //Array 6
 "20", //Array 7
 " The denser the cloud, the brighter Earth's atmosphere is." //Array 8
    };


    /*
    * Button B
    */
    String[] AnswerButtB = {
        "1.25", //Array 0
    "-1 Fahrenheit",  //Array 1
    " 1.5 hours",  //Array 2
    " 12 years", //Array 3
    " 10,000", //Array 4
    " 1.01 pounds of metal", //Array 5//
            "there",  //Array 6
            "Less than 20 ", //Array 7
            " The denser the cloud, the darker Earth's atmosphere is.", //Array 8

    };

    /*
    * Button C
    */


    String[] AnswerButtC = {"1.50", //Array 0
             "1 Fahrenheit",  //Array 1
    "1 hour", //Array 2
    "1.2 years", //Array3
    "200", //Array 4
    "They weigh the same",  // Array 5//
    "they're",  // Array6 //
    "More than 20", //Array 7
    "Both A and B" //Array 8
    };

提醒一下，我已经在 gui 本身上设置了第一个 question/answer，所以它没有存储在数组中。

因为我意识到我的代码有点草率所以我做了这个

questionInS = Integer.toString(questionIndex );

跟踪问题索引值是什么。我想知道为什么当 questionsIndex 值 = -1 时，它会打印出 Array[0]。数组编号确实随着问题的增加而增加，一切正常。但是这让我想知道这个声明

    TextButtA.setText(AnswerButtA[questionIndex]);
    TextButtB.setText(AnswerButtB[questionIndex]);
    TextButtC.setText(AnswerButtC[questionIndex]);

似乎是真的。当 questionIndex 值为 -1 而不是 [0] 时，如何打印出 Array[0]？

Answer 1

多种原因：

questionInS = Integer.toString(questionIndex); 在递增 questionIndex
if(questionIndex < Questions.length -1) 所以你的 Questions 数组是空的，你永远不会进入 if 来增加问题索引。所以你可能需要增加而不考虑条件来增加它。

为什么会这样？（使用数组，增量）

Why is this happening? (Using arrays, increments)

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为什么会这样？ （使用数组，增量）

Why is this happening? (Using arrays, increments)

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为什么会这样？（使用数组，增量）