使用java.util.Stack打印反向文本行

Question

应该从用户读取行，直到输入哨兵“DONE”，此时它们将反向显示。不打印“DONE”字

这里是我的代码，到目前为止我不知道如何得到它的所有一起工作，我知道我已经得太多这一点，但任何帮助将不胜感激

import java.util.Scanner; 
import java.util.Stack; 

public class Turner_A05Q3{ 
    public static void main(String[] args) { 
     Stack<String> stack = new Stack<String>(); 
     ArrayList<String> list = new ArrayList<String>(); 
     System.out.println("Enter text, or done to stop"); 
     Scanner scanner = new Scanner(System.in);  
     List<String> al = new ArrayList<String>(); 
     String word;         
     while (scanner.hasNextLine()) {    
      word = scanner.nextLine();     
      if (word != null) {       
       word = word.trim();      
       if (word.equalsIgnoreCase("done")) {  
        break;         
       } 
       al.add(word);        
      } else { 
       break;         
      } 
     } 
     for (int i=0;i<word.length();i++){ 
      stack.push(word.substring(i,i+1)); 
     } 
     String wordrev = ""; 
     while(!stack.isEmpty()){ 
      wordrev += stack.pop(); 
     } 
     System.out.println("Reverse of the text \"" + wordrev);      
    } 
} 

Answer 1

试着写了这样的循环：

for (int i = word.length(); i > 0; i--) { 
     stack.push(word.substring(i-1, i)); 
    } 

输入：

DONE 

输出：

DONE 

Answer 2

你总是硬道理（完成）的工作，因为你不使用al你只使用变量word的最后内容。

你必须遍历al

尝试：

import java.util.Scanner; 
import java.util.Stack; 
import java.util.ArrayList; 
import java.util.List; 

public class Turner_A05Q3{ 
    public static void main(String[] args) { 
     Stack<String> stack = new Stack<String>(); 
     System.out.println("Enter text, or done to stop"); 

     Scanner scanner = new Scanner(System.in);  
     List<String> al = new ArrayList<String>(); 
     String word=null;   

     while (scanner.hasNextLine()) {    
      word = scanner.nextLine();     
      if (word != null) {       
       word = word.trim();      
        if (word.equalsIgnoreCase("done")) {  
         break;         
        } 
       al.add(word);        
      }else { 
       break;         
      } 
     } 

     for(int j=0;j<al.size();j++){ 
      word = al.get(j);  
      for (int i=0;i<word.length();i++){ 
       stack.push(word.substring(i,i+1)); 
      } 

      String wordrev = ""; 
      while(!stack.isEmpty()){ 
       wordrev += stack.pop(); 
      } 
      System.out.println("Reverse of the text \"" + wordrev);      
     } 
    } 
} 

如果你想显示以相反的顺序的话，而不是文字，请尝试：

public static void main(String[] args) { 
    Stack<String> stack = new Stack<String>(); 
    System.out.println("Enter text, or done to stop"); 

    Scanner scanner = new Scanner(System.in);  
    String word=null;   

    while (scanner.hasNextLine()) {    
     word = scanner.nextLine();     
     if (word != null) {       
      word = word.trim();      
       if (word.equalsIgnoreCase("done")) {  
        break;         
       } 
      stack.push(word);        
     }else { 
      break;         
     } 
    } 

    while(!stack.isEmpty()){ 
     System.out.println("Reverse of the text \"" + stack.pop()); 
    } 
} 

记住， Stack是LIFO（后进先出）