Java Java类

Java .io.StringWriter 类从 String Buffer 流的字符创建字符串。 StringWriter 类的方法也可以在关闭 Stream 后调用，因为这样不会引发 IO 异常。

宣言 ：

public class StringWriter
  extends Writer

构造函数：

• StringWriter() ：使用 String Buffer 的初始或默认大小创建一个新的 StringWriter
• StringWriter(int size) ：使用提到的字符串缓冲区大小创建一个新的 StringWriter

方法：

• write(int char) : Java.io.StringWriter.write(int char)将单个字符写入字符串缓冲区。
  句法：

public void write(int char)
Parameters : 
char : int value of the character to be written.
Return  :
void

• write(String str) : Java.io.StringWriter.write(String str)将字符串写入字符串缓冲区。
  句法：

public void write(String str)
Parameters : 
str : string to be written to the String Buffer.
Return  :
void

• write(String str, int offset, int maxlen) : Java.io.StringWriter.write(String str, int offset, int maxlen)将字符串的一部分写入字符串缓冲区。
  句法：

public void write(String str, int offset, int maxlen)
Parameters : 
str : string to be written to the String Buffer.
offset : start position of the String
maxlen : maximum length upto which string has to written
Return  :
void

• write(char[] carray, int offset, int maxlen) : Java.io.StringWriter.write(char[] carray, int offset, int maxlen)将字符数组的一部分写入字符串缓冲区。
  句法：

public void write(char[] carray, int offset, int maxlen)
Parameters : 
carray : character to be written to the String Buffer
offset : start position of the character array
maxlen : maximum no. of the character of the carray has to written
Return  :
void

• toString() : Java.io.StringWriter.toString()将字符串缓冲区的值作为字符串返回
  句法：

public String toString()
Parameters : 
-----------
Return  :
string value of the String Buffer

• close() : Java.io.StringWriter.close()关闭字符串缓冲区。由于方法也可以在关闭字符串缓冲区后调用，所以它没有任何作用。
  句法：

public void close()
Parameters : 
-----------
Return  :
void

说明使用 StringWriter 类方法的Java程序：

Java

// Java program illustrating the working of StringWriter class methods
// write(int char), write(String str), close()
// write(String str, int offset, int maxlen), toString()
// write(char[] carray, int offset, int maxlen)
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Initializing String Writer
        StringWriter geek_writer1 = new StringWriter();
        StringWriter geek_writer2 = new StringWriter();
        StringWriter geek_writer3 = new StringWriter();
        StringWriter geek_writer4 = new StringWriter();
 
        // Use of write(int char) : to write a character
        geek_writer1.write(71);
        geek_writer1.write(70);
        geek_writer1.write(71);
 
        // Use of toString() : Value written by write(int char)
        System.out.println("Using write(int char) : "+ geek_writer1.toString());
 
        String str = "Hello Geeks";
        // Use of write(String str) : to write string
        geek_writer2.write(str);
 
        // Value written by write(String str)
        System.out.println("Using write(String str) : "+ geek_writer2.toString());
 
        // Use of write(String str, int offset, int maxlen) : to write part of string
        geek_writer3.write(str, 2, 4);
        geek_writer3.write(str, 5, 6);
 
        // Value written by write(String str, int offset, int maxlen)
        System.out.println("Using write(str, offset, maxlen) : "
                                                + geek_writer3.toString());
 
        try
        {
            // Use of Close() method : to close the geek_writer4
            // But no use as String Writer method is still working with it
            geek_writer4.close();
        }
         
        catch (IOException except)
        {
            System.out.println("ERROR");
            except.printStackTrace();;
        }
 
 
        // Initializing character array
        char[] carray = str.toCharArray();
         
        // Use of write(char[] carray, int offset, int maxlen):
        // to write part of char array
        geek_writer4.write(carray, 4, 6);
 
        // Value written by write(String str, int offset, int maxlen)
    System.out.println("Using write(carray, offset, maxlen) : "
                                        + geek_writer4.toString());
 
    }
}

输出 ：

Using write(int char) : GFG
Using write(String str) : Hello Geeks
Using write(str, offset, maxlen) : llo  Geeks
Using write(carray, offset, maxlen) : o Geek

• append(char Sw) : Java.io.StringWriter.append(char Sw)将单个字符附加到字符串缓冲区。
  句法：

public StringWriter append(char Sw)
Parameters : 
Sw : character to be append
Return  :
StringWriter

• append(CharSequence char_sq) : Java.io.StringWriter.append(CharSequence char_sq)将指定的字符序列附加到字符串缓冲区。
  句法：

public StringWriter append(CharSequence char_sq)
Parameters : 
char_sq : Character sequence to append. 
Return  :
StringWriter, if char sequence is null, then NULL appends to the StringWriter.

• append(CharSequence char_sq, int start, int end) : Java.io.StringWriter.append(CharSequence char_sq, int start, int end)将字符序列的指定部分附加到字符串缓冲区。
  句法：

public StringWriter append(CharSequence char_sq, int start, int end)
Parameters : 
char_sq : Character sequence to append.
start : start of character in the Char Sequence
end : end of character in the Char Sequence
Return  :
void

• flush() : Java.io.StringWriter.flush()刷新 StringWriter 流
  句法：

public void flush()
Parameters : 
-----
Return  :
void

• getBuffer() : Java.io.StringWriter.getBuffer()返回StringWriter的String Buffer。
  句法：

public StringBuffer getBuffer()
Parameters : 
-----------
Return  :
String Buffer with its current value.

说明 StringWriter 类方法使用的Java程序：append(CharSequence char_sq)、append(char Sw)、append(CharSequence char_sq, int start,int end)、flush()、getgetBuffer()

Java

// Java program illustrating the working of StringWriter class methods
// append(CharSequence char_sq), append(char Sw)
// append(CharSequence char_sq, int start,int end)
// flush(), getgetBuffer()
   
import java.io.*;
   
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Initializing String Writer
        StringWriter geek_writer1 = new StringWriter();
        StringWriter geek_writer2 = new StringWriter();
        StringWriter geek_writer3 = new StringWriter();
   
   
        // Use of write(int char) : to write a character
        geek_writer1.write(71);
        geek_writer1.write(70);
        geek_writer1.write(71);
   
   
        // Use of toString() : Value written by write(int char)
        System.out.println("Using write(int char) : "+ geek_writer1.toString());
   
        // Using flush() method
        geek_writer1.flush();
        System.out.println("Using flush() : "+geek_writer1.toString());
   
        // Use of append(char Sw)
        System.out.println("append(char Sw) : " + geek_writer1.append(" 1GFG1"));
   
        // Use of getBuffer() :
        System.out.println("Using geek_writer1 : " + geek_writer1.getBuffer());
   
   
        // Initializing Character Sequence
        CharSequence char_sq1 = "1 Hello 1";
        CharSequence char_sq2 = " : 2 Geeks 2";
   
        // Use of append(CharSequence char_sq)
        geek_writer2.append(char_sq1);
        geek_writer2.append(char_sq2);
   
        System.out.println("append(char_sq) : " + geek_writer2.toString());
   
        // Use of append(CharSequence char_sq,int start,int end)
        geek_writer3.append(char_sq1, 0, 3);
        geek_writer3.append(char_sq2, 3, 6);
   
     System.out.println("append(char_sq,start,end) : " + geek_writer3.toString());
   
    }
}

输出 ：

Using write(int char) : GFG
Using flush() : GFG
append(char Sw) : GFG 1GFG1
Using geek_writer1 : GFG 1GFG1
append(char_sq) : 1 Hello 1 : 2 Geeks 2
append(char_sq,start,end) : 1 H2 G