Java将文本文件的内容放入数组然后显示和操作数组内容的问题

时间：2015-11-11 19:00:20

标签： java arrays inputstream

好的，所以这是一个学校项目，我似乎无法弄清楚我做错了什么，我意识到有更好的方法来做很多这个但是必须这样做（我会注意到）特别是什么）。

我需要写两个非常简单的程序。

  1. 第一个程序创建一个300个随机整数的文件，范围为1到54，然后打印到文本文件。

  2. 第二个程序读取该文本文件并将内容转换为数组。然后对数组进行操作以输出一些内容，数字的平均值以及数字在特定范围内出现的次数。我也试图把整个阵列放在一边。不幸的是，所有部分基本上都不起作用，或者我不理解某些事情，我很确定它们都是lol。

    3. 计划1如下

    import java.util.*;
import java.io.*;
public class OutStream{ 
public static void main(String[] args){
int Counter = 0,
    Value;
Random Gen = new Random();
System.out.println("Generating Numbers and Text File Now");
   try{
        File out = new File("F:\\Text.txt");
        PrintWriter P = new PrintWriter(out);
        while(Counter <= 300){
            Value = Gen.nextInt(54)+1;
            P.println(Value);
            ++Counter;
            System.out.println("Value: " + Value);
        } 
        P.close();
  }catch(Exception E){ 
  E.printStackTrace();
  System.out.println(E.getMessage());
  } 
  System.out.println("The Program has ended");
 }   
}

    第二个计划是全部崩溃的地方。 

    import java.util.*;
import java.io.*;
public class InStream {

public static void main(String[] args) {
int [] NumArray = new int[301];
int PosNum = 0,
    Total = 0,
    Average = 0,
    Range1 = 0,
    Range2 = 0,
    Range3 = 0,
    Range4 = 0,
    Range5 = 0,
    Range6 = 0;

    try{
        File Fout = new File("F:\\Text.txt");
        PosNum = 0;
        Scanner Fin = new Scanner(Fout);
        while(Fin.hasNextInt()){
            NumArray[++PosNum] = Fin.nextInt();


        }
        Fin.close();

       }catch(Exception E){
           E.printStackTrace();
           System.out.println("***ERROR ***** " + E.getMessage());
       } 


for(NumArray[PosNum] = 0; NumArray[PosNum] <= 301;){
    Total += NumArray[PosNum++];

    if(NumArray[Range1] >= 1 && NumArray[Range1] <= 10){
       Range1++;
    }

    if (NumArray[Range2] >= 11 && NumArray[Range2] <= 20){
        Range2++;
    }
    if(NumArray[Range3] >= 21 && NumArray[Range3] <= 30){
       Range3++;
    }
    if(NumArray[Range4] >= 31 && NumArray[Range4] <= 40){
       Range4++;
    }
    if(NumArray[Range5] >= 41 && NumArray[Range5] <= 50){
       Range5++;
    }
    if(NumArray[Range6] >= 51 && NumArray[Range6] <= 54){
       Range6++;
    }  

}
Average = Total / 301;
System.out.println("The Average Is: " + Average);
System.out.println("1 Through 10 appear: " + Range1 + " Times");
System.out.println(" 11 Through 20 appear: " + Range2 + "Times");
System.out.println("21 Through 30 appear: " + Range3 + " Times");
System.out.println("31 Through 40 appear: " + Range4 + " Times");
System.out.println("41 Through 50 appear: " + Range5 + " Times");
System.out.println("51 Through 54 appear: " + Range6 + " Times");
 }

}

    这是我最新的尝试。 

    import java.util.*;
import java.io.*;
public class FixedInstream {

public static void main(String[] args) {
    int [] MyArray = new int[301];
    int PosNum = 0,
        Average,
        Total = 0,
        R1 = 0,
        R2 = 0,
        R3 = 0,
        R4 = 0,
        R5 = 0,
        R6 = 0,
        R7 = 0;

    try{
        File Fout = new File("F:\\Text.txt");
        PosNum = 0;
        Scanner Fin = new Scanner(Fout);
        while(Fin.hasNextInt()){
            MyArray[PosNum] = Fin.nextInt();
            Total += MyArray[PosNum];
        }
        Fin.close();

    }catch(Exception E){
           E.printStackTrace();
           System.out.println("***ERROR ***** " + E.getMessage());
       } 
    for(MyArray[PosNum] = 0; MyArray[PosNum] <= 300; ++MyArray[PosNum]){


        if(MyArray[R1] >= 1 && MyArray[R1] <= 10){
            R1++;
        }

        if (MyArray[R2] >= 11 && MyArray[R2] <= 20){
            R2++;
        }
        if(MyArray[R3] >= 21 && MyArray[R3] <= 30){
            R3++;
        }
        if(MyArray[R4] >= 31 && MyArray[R4] <= 40){
            R4++;
        }
        if(MyArray[R5] >= 41 && MyArray[R5] <= 50){
            R5++;
        }
        if(MyArray[R6] >= 51 && MyArray[R6] <= 54){
            R6++;
        }  
    }

    Average = Total / 301;
    System.out.println("The Average Is: " + Average);
    System.out.println("1 Through 10 appear: " + R1 + " Times");
    System.out.println("11 Through 20 appear: " + R2 + " Times");
    System.out.println("21 Through 30 appear: " + R3 + " Times");
    System.out.println("31 Through 40 appear: " + R4 + " Times");
    System.out.println("41 Through 50 appear: " + R5 + " Times");
    System.out.println("T51 Through 54 appear: " + R6 + " Times");
  }

}

    该程序没有正确放置下面的示例我显然忘记在我的初始评论中添加。

    输出：

    The Average Is: 27
The Numbers 1 Through 10 appear: 1 Times
The Numbers 11 Through 20 appear: 1 Times
The Numbers 21 Through 30 appear: 1 Times
The Numbers 31 Through 40 appear: 1 Times
The Numbers 41 Through 50 appear: 1 Times
The Numbers 51 Through 54 appear: 1 Times

    文本文件中有300个数字1 - 54这些数字的重复方式不同但通常是10 - 50倍，因为你可以看到它只显示一次，这让我相信我不会增加一些东西正确。

1 个答案:

答案 0 :(得分：2)

我认为这里有很多令人困惑的事情......以下是答案，但我建议你自己尝试调试这个片段以了解问题所在。

  1. 你正在通过一个包含301个单元格的数组。数组索引从0变为length-1。当posNum初始化为0时，当你使用numArray[++posNum]时，第一个索引将是++0 = 1。所以你永远不会到达阵列的第一个单元格。这导致out of range exception，因为最后一个索引将是301，但实际上最后一个索引是300 ...只需阅读异常消息就可以引导您找到解决方案。

  2. 我建议你看一下for loop如何使用NumArray[Range1] 来理解如何逐个单元地使用增量索引浏览数组。然后你会像这样纠正你的for循环：

    for（int idx = 0; idx＆lt; NumArray.length; idx ++）

  3. 您正在使用错误的变量访问当前单元格。这可以附加，但你会在调试模式下非常快地检测到它......

    NumArray [IDX]

    4. 而不是

    variables

    1. 这对于使您的程序工作并不重要，但在Java中有一些约定（如在每个语言中）和camelCase都是用public static void main(String[] args) { int [] NumArray = new int[301]; int PosNum = 0, Total = 0, Average = 0, Range1 = 0, Range2 = 0, Range3 = 0, Range4 = 0, Range5 = 0, Range6 = 0; try{ File Fout = new File("F:\\Text.txt"); PosNum = 0; Scanner Fin = new Scanner(Fout); while(Fin.hasNextInt()){ NumArray[PosNum++] = Fin.nextInt(); } Fin.close(); }catch(Exception E){ E.printStackTrace(); System.out.println("***ERROR ***** " + E.getMessage()); } for(int idx = 0; idx < NumArray.length; idx++){ Total += NumArray[idx]; if(NumArray[idx] >= 1 && NumArray[idx] <= 10){ Range1++; } if (NumArray[idx] >= 11 && NumArray[idx] <= 20){ Range2++; } if(NumArray[idx] >= 21 && NumArray[idx] <= 30){ Range3++; } if(NumArray[idx] >= 31 && NumArray[idx] <= 40){ Range4++; } if(NumArray[idx] >= 41 && NumArray[idx] <= 50){ Range5++; } if(NumArray[idx] >= 51 && NumArray[idx] <= 54){ Range6++; } } Average = Total / 301; System.out.println("The Average Is: " + Average); System.out.println(" 1 Through 10 appear: " + Range1 + " Times"); System.out.println("11 Through 20 appear: " + Range2 + " Times"); System.out.println("21 Through 30 appear: " + Range3 + " Times"); System.out.println("31 Through 40 appear: " + Range4 + " Times"); System.out.println("41 Through 50 appear: " + Range5 + " Times"); System.out.println("51 Through 54 appear: " + Range6 + " Times"); } 编写的。

      公共类InStream {

      {{1}}

      }

      2. 不要犹豫，调试你的程序，这是学习语言，享受Java的最好方法

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