使用java中的流緩衝區類從字符串中刪除子串字符串錯誤 - 驗證

Question

子字符串使用java中的流緩衝區類從字符串中刪除。 輸出來錯：

請覈實該計劃

見我的輸出和解釋程序是什麼？ 什麼是必要的輸出，以及程序中必須做些什麼改變才能獲得更正輸出？

import java.io.*; 
public class Strbuff 
{ 
    public static void main(String arg[])throws IOException 
    { 
     BufferedReader in=new BufferedReader(new InputStreamReader(System.in)); 
     String str; 
     try 
     { 
      System.out.println("Enter your name"); 
      str=in.readLine(); 
      str+="\nThis is example for string Buffer class and its function"; 
      StringBuffer strbuf=new StringBuffer(); 
      strbuf.append(str); 
      System.out.println(strbuf); 
      strbuf.delete(0,str.length()); 
      strbuf.append("hello"); 
      strbuf.insert(5,"-java"); 
      System.out.println(strbuf); 
      strbuf.reverse(); 
      System.out.println("Reversed string"); 
      System.out.println(strbuf); 
      strbuf.reverse(); 
      System.out.println(strbuf); 
      strbuf.setCharAt(5,' '); 
      System.out.println(strbuf); 
      System.out.println("Character at 6th position"); 
      System.out.println(strbuf.substring(3,7)); 
      strbuf.deleteCharAt(3); 
      System.out.println(strbuf); 
      System.out.println("Capacity of the string Buffer object"); 
      System.out.println(strbuf.capacity()); 
      strbuf.delete(6,strbuf.length()); 
      System.out.println("The string with first 6 letters"); 
      System.out.println(strbuf); 
     } 
     catch(StringIndexOutOfBoundsException e) 
     { 
      System.out.println(e.getMessage()); 
     } 
    } 
} 

Answer 1

這是基本的初學者材料，您必須已經覆蓋並觸及到可以讓您確定此代碼的功能的方法。至少你會得到你所需的閱讀材料（或地點）來執行所要求的任務。

所有你需要做的是實際上做什麼問你。相反，你認爲你會來到StatckOverflow並讓其他人爲你做功課，這不是論壇的目的。我們在這裏是爲了幫助您在走上成爲一名Java程序員的道路上絆倒您的絆腳石，但您至少在遇到絆腳石時顯示出自己的嘗試。在這裏複製/粘貼您的作業代碼不被視爲嘗試。

逐行瀏覽每行代碼，並放置註釋，該註釋包含該行對每行的操作的簡要描述。如果您不知道代碼行的功能，請閱讀您遇到問題的方法。用這種方法嘗試不同的事情，在你知道它之前，你會對它有完整的理解。

，我會幫助你開始：

// Open a BufferReader InputStream and establish it as variable 'in'... 
BufferedReader in=new BufferedReader(new InputStreamReader(System.in)); 

// Declare a String variable named 'str'. This string is not originally 
//initialized so I'm going to do that now with a Null String... 
String str = ""; 

// Establish a try/catch block to trap a StringIndexOutOfBoundsException 
// should it ever occur. This exception is thrown by String methods to 
// indicate that an index is either negative or greater than the size of 
// the string. For some methods such as the charAt method, this exception 
// also is thrown when the index is equal to the size of the string. We 
// want to catch this exception so it doesn't crash our program... 
try { 

    // Print to the display console for User to enter his/her name... 
    System.out.println("Enter your name"); 

    // Read what the User supplied and place the text into our 'str' 
    // String variable... 
    str=in.readLine(); 

    // Add (append) the string "\nThis is example for string Buffer class 
    // and its function" to the 'str' string variable. The '\n' is a output 
    // string tag for establishing a new line within the displayed output. 
    // the '+=' attached to our 'str' variable is a Assignment Operator. It 
    // tells the compiler to adds the right operand to the left operand and 
    // assign the result to left operand. It is the same as writing: 
    // str = str + "\nThis is example for string Buffer class and its function"; 
    str+="\nThis is example for string Buffer class and its function"; 

    // Establish a String Buffer and name it 'strbuf. A StringBuffer is a 
    // thread-safe, mutable sequence of characters. A string buffer is like a 
    // String, but can be modified... 
    StringBuffer strbuf=new StringBuffer(); 

    // Place our current string held within the 'str' string variable into our 
    // new String Buffer (strbuf). The StringBuffer.append() method is used for 
    // this... 
    strbuf.append(str); 

    // Print the contents within out string buffer (strbuf) to the display 
    // console... 
    System.out.println(strbuf); 

    // Now Delete (clear) everything within our String Buffer variable (strbuf). 
    // This is done using the StringBuffer.delete() method. 0 indicates the starting 
    // point index for the number of characters within the string we want to delete. 
    // The 'str.length()' portion indicates the ending index point to delete. The 
    // 'str.length()' method always returns the length of (number of characters) within 
    // the string variable (str). So, we know our string variable 'str' contains: 
    // the User provided name, let's say: "Vikraman" plus "\nThis is example for string 
    // Buffer class and its function" which in total is 66 characters in length but 
    // because indexing always starts from 0 the length of the string (str) is 65. Our 
    // line below could be written strbuff.delete(0, 65). Delete characters within the 
    // string buffer variable (strbuf) starting from index 0 (the first character) to 
    // index 65 (the last character). 
    strbuf.delete(0,str.length()); 

    .................................... 
    .................................... 
    ........ You Do The Rest ......... 
    .................................... 
    .................................... 

} 
catch(StringIndexOutOfBoundsException e) { 
    // Display the exception message to console. 
    System.out.println(e.getMessage()); 
} 

是...的意見是過度和古老但你用它做的時候，你會成爲一名職業與一段代碼。 ;）