在main方法中访问变量

时间:2013-03-09 18:51:23

标签: java

我是Java的新手,编写这个程序来改变单词并修复单词。以下是我的计划。在我调用mix()之后,我希望能够将单词的输出分配给main中的team数组。

出于某种原因,我可以调用mix()它可以工作,但是我无法访问shuffle函数中的单词。由于我在main并且所有这些功能都在main内,我以为我可以访问这些变量。我在这里缺少什么想法?

import java.util.Scanner;
import java.io.*;
import java.util.*;

public class Project2
{


    public static void main(String[] args) 
    {


                System.out.println("Select an item from below: \n");
                System.out.println("(1) Mix");
                System.out.println("(2) Solve");
                System.out.println("(3) Quit");


                int input;
                Scanner scan= new Scanner(System.in);
                input = scan.nextInt();

                //System.out.println(input);  
                if(input==1) {
                    mix();
                    System.out.println(word);
                    char team[]=word.toCharArray();
                    for(int i=0;i<team.length;i++){
                        System.out.println("Data at ["+i+"]="+team[i]);
                    }
                }
                else{
                    System.out.println("this is exit");
                    } 
        }




        static void mix()
         {
        String [] lines=new String[1000];//Enough lines.
        int counter=0;
        try{
            File file = new File("input.txt");//The path of the File
            FileReader fileReader1 = new FileReader(file);
            BufferedReader buffer = new BufferedReader(fileReader1);
            boolean flag=true;
            while(true){
                try{
                    lines[counter]=buffer.readLine();//Store a line in the array.
                    if(lines[counter]==null){//If there isn't any more lines.
                        buffer.close();
                        fileReader1.close();
                        break;//Stop reading and close the readers.

                    }
                    //number of lines in the file
                    //lines is the array that holds the line info
                    counter++;

                    }catch(Exception ex){
                        break;
                    }
            }

            }catch(FileNotFoundException ex){
                System.out.println("File not found.");
            }catch(IOException ex){
                System.out.println("Exception ocurred.");
            }


                int pick;
                 Random rand = new Random();
                 pick = rand.nextInt(counter ) + 0;

                System.out.println(lines[pick]);
                ///scramble the word

                shuffle(lines[pick]);


    }

    static void shuffle(String input){
        List<Character> characters = new ArrayList<Character>();
        for(char c:input.toCharArray()){
            characters.add(c);
        }

        StringBuilder output = new StringBuilder(input.length());
        while(characters.size()!=0){
            int randPicker = (int)(Math.random()*characters.size());
            output.append(characters.remove(randPicker));
        }

        String word=output.toString();


    }


  }

2 个答案:

答案 0 :(得分:2)

使用return语句从shuffle()方法返回字符串值:

static String shuffle(String input) {
     // . . .
     return output.toString();
}

...然后在mix中使用它:

String word = shuffle(lines[pick]);

但在编程之前最好read basic java tutorials

答案 1 :(得分:1)

在Java中,变量不能在它们初始化的方法之外看到。例如,如果我在main中声明int foo = 3;,然后我尝试从另一个方法访问foo,它赢了不行。从另一种方法的角度来看,foo甚至不存在!

在方法之间传递变量的方法是使用return <variable>语句。一旦程序到达return语句,该方法将退出,return(可能foo)之后的值将返回给调用方法。但是,你必须说当你声明那个方法时,该方法返回一个变量(并说明是什么类型)(就像你在方法没有返回任何内容时需要说void一样!)。

public static void main(String[] args){
     int foo = 2;
     double(foo); //This will double foo, but the new doubled value will not be accessible
     int twoFoo = double(foo); //Now the doubled value of foo is returned and assigned to the variable twoFoo
}

private static int double(int foo){//Notice the 'int' after 'static'. This tells the program that method double returns an int. 
     //Also, even though this variable is named foo, it is not the same foo
     return foo*2;
}

或者,您可以使用实例变量来获取类中所有方法都可以访问的变量,但是如果您是Java新手,则在开始学习面向对象编程的基础知识之前,应该避免这些变量。

希望这有帮助! -BritKnight