java - LinkedList 永远不会终止 Java 中的输入

Question

我正在用Java制作一个链表程序。但是，当我调用方法 get_values(); 时它不断要求输入。我似乎无法阻止它。由于我无法找出代码中的问题，因此我将整个程序代码粘贴到此处。

import java.io.*; //Importing Java Input-Output Library
class Node
{
    int x;
    Node next; //Initializing Node data type named next
    Node() //method to set all values to 0
    {
        x=0;
        next=null;
    }

    void get_data(int a) //get data from user
    {
        x=a;
    }

    int put_data() // print returned values
    {
        return x;
    }
}

class List
{
    Node start; //Another node (user created variable)
    List()
    {
        start=null;
    }

    void Add_Node(int a) // Add or Creating new nodes and linking them
    {
        Node n=new Node();
        n.get_data(a);
        if(start==null)
        {
            start=n;
        }
        else if(start!=null)
        {
            for(Node temp=start, prev=start; temp!=null; prev=temp, temp=temp.next) //sorting
            {
                if(temp.x>n.x && temp==start)
                {
                    n.next=temp;
                    start=n;
                }
                else if(temp.x<n.x && temp.next==null)
                {
                    temp.next=n;
                }
                else if(temp.x>n.x && prev.x<n.x)
                {
                    n.next=temp;
                    prev.next=n;
                }
                }
            }
        }
    void traverse() //printing traversed values
    {
        for(Node temp=start; temp!=null; temp=temp.next)
        {
            System.out.print(temp.put_data()+"  ");
        }
    }
    void extraction(int b) throws IOException
    {
        InputStreamReader ist=new InputStreamReader(System.in);
        BufferedReader br=new BufferedReader(ist);
        int a;
        for(int i=0; i<5; i++)
        {   
            System.out.println("Enter the value for node "+i+":");
            a=Integer.parseInt(br.readLine()); 
            Add_Node(a);
        }
        traverse();
        Node store_new=null;
        boolean match_check=false;
        for(Node temp=start, prev=start; temp!=null; prev=temp, temp=temp.next)
        {
            if(temp.x==b && temp!=null)
            {
                match_check=true;
                store_new=temp;
                break;
            }
            else if(temp.x!=b)
            {
                //match_check=false;
            }
        }
        if(match_check==true)
        {
            System.out.println("Value found. The value address is: "+store_new+" and the value stored in it is: "+store_new.x);
        }
        else if(match_check==false)
        {
            System.out.println("Value not found in the list, please enter a value which exists in the list.");
            System.exit(0);
        }
    }
}

public class LinkedList //main class
{
    static void get_values() throws IOException
    {
        InputStreamReader ist=new InputStreamReader(System.in);
        BufferedReader br=new BufferedReader(ist);
        List l=new List();
        int a;
        for(int i=0; i<5; i++)
        {   
            System.out.println("Enter the value for node "+i+":");
            a=Integer.parseInt(br.readLine()); 
            l.Add_Node(a);
        }
        l.traverse();
    }
    static void extract() throws IOException
    {
        InputStreamReader ist=new InputStreamReader(System.in);
        BufferedReader br=new BufferedReader(ist);
        List l=new List();
        int b;
        System.out.println("Enter the value for extraction: ");
        b=Integer.parseInt(br.readLine());
        l.extraction(b);
    }
    static void sublist()
    {

    }
    public static void main(String[] args) throws IOException
    {
        InputStreamReader ist=new InputStreamReader(System.in);
        BufferedReader br=new BufferedReader(ist);
        List l = new List();
        int input;
        boolean Menu_check=false;
        System.out.println("Enter a the corresponding number to select the menu and then press enter");
        System.out.println("1. Enter values and traverse them");
        System.out.println("2. Enter a value and find it in the list");
        System.out.println("3. Enter a range to be extracted from the list");
        System.out.println("4. Exit?");
        input=Integer.parseInt(br.readLine());
        if(input<5 && input>0)
        {
            Menu_check=true;
        }
        while(Menu_check=true)
        {
            switch(input)
            {
                case 1: get_values();
                        break;
                case 2: extract();
                        break;
                case 3: sublist();
                        break;
                case 4: System.out.println("Goodbye");
                        System.exit(0);
                        break;
            }
        }
    }  
}

有人可以检查一下我的代码并帮助我吗？

Answer 1

1. 在 java 中比较基元与 ==

2. 存在逻辑错误。我认为您想再次询问用户输入，但输入仍然是 4，并且只有在输入小于 5 且大于 0 时才执行某些操作。

将你的 main 更改为:

    InputStreamReader ist=new InputStreamReader(System.in);
    BufferedReader br=new BufferedReader(ist);
    List l = new List();
    int input;

    while(true)
    {
        System.out.println("Enter a the corresponding number to select the menu and then press enter");
        System.out.println("1. Enter values and traverse them");
        System.out.println("2. Enter a value and find it in the list");
        System.out.println("3. Enter a range to be extracted from the list");
        System.out.println("4. Exit?");
        input=Integer.parseInt(br.readLine());

        if(input<5 && input>0)
        {
            switch(input)
            {
                case 1: get_values();
                        break;
                case 2: extract();
                        break;
                case 3: sublist();
                        break;
                case 4: System.out.println("Goodbye");
                        System.exit(0);
                        break;
            }
        }
    }

您还可以删除情况 4 并执行 while(input != 4) 而不是 while(true)。如果您这样做，则必须使用不等于 4 的值来初始化 input。