Question

我想阅读一个文本文件，然后在Java中打印已知单词xxx之前的单词。我已经使用Scanner类在java中编写了这段代码。但是这段代码只打印了“xxx”之前的一半字，而“xxx”之前的其他一些字则丢失了。我想知道问题是什么，你可以解决这个问题。

测试文件包含

之类的内容

Blah blah blah.. man xxx create blah blah .. wander xxx blah... then xxx ..
Need to print man,wander,then etc.,

public class Searchright {
    public static void main(String[] args) throws IOException {

        Scanner s = null;
        String str;

        try {
            s = new Scanner(new BufferedReader(new FileReader("doc.txt")));
            str=s.next();
         do{
            //while (s.hasNext()) {
                 str=s.next();
                if((s.hasNext(("xxx"))||s.hasNext(("X.X.X”))))
               {
                        //System.out.println(s.next()+" "+s.next() );
                        //System.out.println(s.next());     
                        System.out.println(str);
                        //s.next();
                    }

              s.next();
            //System.out.println(s.next());

            }while(s.hasNext());
        }

        finally{
            if (s != null) {
                //s.close();
            }
        }
    }
    }

Answer 1

您的代码已打印man和wander，但缺少then。我已经更新了你的代码以使用try资源而不是try-finally，并将下一个字分配给一个自己的变量，该变量经过测试所需的字符串：

public static void main(String[] args) throws IOException 
{
    try (Scanner s = new Scanner(new BufferedReader(new FileReader("doc.txt"))))
    {
        String str=s.next();
        String next;

        do
        {
            next = s.next();
            if( next.equals("xxx") || next.equals("X.X.X") )
            {
                // Need to print man,wander,then etc.,   
                System.out.println(str);
            }
            str = next;
        }
        while(s.hasNext());
    }
}

HTH

Answer 2

public class Searchright {
    public static void main(String[] args) throws IOException {

    Scanner s = null;
    String str;

    try {
        s = new Scanner(new BufferedReader(new FileReader("doc.txt")));
     do{
        //while (s.hasNext()) {
             str=s.next();
            if((s.hasNext(("xxx"))||s.hasNext(("X.X.X”))))
           {
                    //System.out.println(s.next()+" "+s.next() );
                    //System.out.println(s.next());     
                    System.out.println(str);
                    //s.next();
                }

        //System.out.println(s.next());

        }while(s.hasNext());
    }

    finally{
        if (s != null) {
            //s.close();
        }
    }
}
}

在s.next()之前和do loop阻止while之前删除do loop。它在一个循环中逃避了两次单词。这导致了缺失的单词。

Answer 3

问题很简单：你在循环中调用Scanner.next 2次而不是1次：这应该有效：

public class Searchright {
    public static void main(String[] args) throws IOException {

        Scanner s = null;
        String str;

        try {
            s = new Scanner(new BufferedReader(new FileReader("doc.txt")));
            str=s.next();
         do{
            //while (s.hasNext()) {
                 str=s.next();
                if((s.hasNext(("xxx"))||s.hasNext(("X.X.X”))))
               {
                        //System.out.println(s.next()+" "+s.next() );
                        //System.out.println(s.next());     
                        System.out.println(str);
                        //s.next();
                    }

              //-> ADDED COMMENT HERE -------------------------- s.next();
            //System.out.println(s.next());

            }while(s.hasNext());
        }

        finally{
            if (s != null) {
                //s.close();
            }
        }
    }
}

我认为代码应该与问题中的代码类似。它只是添加了以“// - ＆gt; ADDED COMMENT HERE”开头的评论

使用java提取文本文件中特定单词旁边的单词

3 个答案: