打印数组列表中的特定部分

Question

所以我有一个Arraylist持有一个类，如下面的代码所示。

NewStorage.java是文件名包含以下

package postit; 

import java.util.ArrayList; 
import java.util.Scanner; 

public class NewStorage extends NoteInfomation { 

    Scanner inputID = new Scanner(System.in); 
    Scanner NoteID = new Scanner(System.in); 

    int count = 0; 

    ArrayList<NoteInfomation> Note = new ArrayList<NoteInfomation>(20); 

    public void printinfo() { 
     System.out.println("--- Fill note here ---"); 
    } 

    public void Notestore() { 

     System.out.println("Enter the note ID you wish to attach the note with\n\n"); 
     inputIDnote = inputID.nextLine(); 
     System.out.println("Enter your note\n\n"); 
     noteDescription = NoteID.nextLine(); 
     System.out.println("" + inputIDnote); 
     System.out.println("" + noteDescription); 
    } 

    public void PrintNotes() { 

     for (int i = 0; i < Note.size(); i++) { 
      System.out.println(" " + Note.get(i)); 

     } 
    } 
} 

所示的代码请看下面

package postit; 

import java.util.Scanner; 

public class Postit { 

    public static void main(String[] args) { 
     int MenuOption = 0; 

     NewStorage G = new NewStorage(); // Case 1 Object 

     while (MenuOption != 3) { 

      System.out.println(
        "\n--------Note System-------\n" + 
          "----------------------------\n" + 
          "1. Create a Note \n" + 
          "2. View Notes \n" + 
          "3. Close Program\n" + 
          "----------------------------\n" 
      ); 

      Scanner menu = new Scanner(System.in); 
      MenuOption = menu.nextInt(); 

      switch (MenuOption) { 
       case 1: 
        G.printinfo(); 
        G.Notestore(); 
        break; 
       case 2: 
        G.PrintNotes(); 
        break; 
       case 3: 
        System.out.println("Program is closing"); 
        System.exit(0); 
        break; 
       default: 
        System.out.println("Invalid choice."); 
        break; 
      } 
     } 
    } 
} 

命名Postit.java主文件最后，这是note.java文件，其中包含了NoteInfomation用于数组的类。

package postit; 

class NoteInfomation { 
    String inputIDnote; 
    String noteDescription; 
} 

所以，我的问题是，如图所示的代码程序应该问他们想得分配自己的笔记内容记ID的用户。然后用户可以通过输入相应的笔记ID来查看他们创建的笔记。理想情况下，当我建立在程序上时，我还希望程序让用户从之前创建的ID列表中选择，以记住创建的笔记的ID，这不是问题。提前致谢。

Answer 1

代码中有很多错误。您没有在Notestore()方法中存储任何注释。 PrintNode()也不起作用。

更改您的代码是这样的..

NoteInfomation.java

class NoteInfomation { 
    String inputIDnote; 
    String noteDescription; 
    public NoteInfomation(String inputIDnote, String noteDescription) { 
     this.inputIDnote = inputIDnote; 
     this.noteDescription = noteDescription; 
    } 
    @Override 
    public String toString() { 
     return "Id:" + inputIDnote + ", Description: " + noteDescription; 
    } 
} 

Nodestore（）方法...

public void Notestore() { 

    System.out.println("Enter the note ID you wish to attach the note with\n\n"); 
    String inputIDnote = inputID.nextLine(); 
    System.out.println("Enter your note\n\n"); 
    String noteDescription = inputID.nextLine(); //No need for two scanner 
    System.out.println("" + inputIDnote + "\n" + noteDescription); 
    Note.add(new NoteInfomation(inputIDnote, noteDescription)); 
} 

PrintNotes（）方法

public void PrintNotes() { 

    for (int i = 0; i < Note.size(); i++) { 
     System.out.println(" " + Note.get(i).toString()); 

     //**or you can also use this 
     // System.out.println("Id:" + Note.get(i).inputIDnote + ", Description: " + Note.get(i).noteDescription); 

    } 
} 

我鼓励你研究如何ArrayList的作品。