Java is wide range and used in various applications.<\/p>\n
PushbackReader is discussed in a detailed manner. It allows characters to be pushed back into the Stream. The unread() method of this class allows us to pushback the characters.<\/p>\n
PushbackReader pushbackReader =\r\n new PushbackReader(new FileReader(\" \"))<\/pre>\nDeclaration:<\/h3>\n
public class PushbackReader extends FilterReader<\/pre>\nParameter:<\/h4>\n
\n
- C is the int value of the character that has to be pushed back.<\/li>\n<\/ul>\n
Return Value:<\/strong>
\nIt does not return any Value<\/p>\nException:<\/h4>\n
\n
- IOException \u2212 When an I\/O error occurs or the pushback buffer fills up.<\/li>\n<\/ul>\n
Read characters:<\/h4>\n
It used to read the characters of pushbackreader:<\/p>\n
int aChar = pushbackReader.read();\r\nwhile(aChar != -1) {\r\n System.out.println((char) aChar);\r\n aChar = pushbackReader.read();\r\n}<\/pre>\nClass Methods:<\/h3>\n
\n\n
\n Method<\/strong><\/td>\n Description<\/strong><\/td>\n<\/tr>\n \n int read()<\/span><\/td>\n It reads one character at a time.<\/span><\/td>\n<\/tr>\n \n void mark(int readAheadLimit)<\/span><\/td>\n It serves as a marker for the current location within a stream.<\/span><\/td>\n<\/tr>\n \n boolean ready()<\/span><\/td>\n It is employed to determine when the stream is prepared for reading.<\/span><\/td>\n<\/tr>\n \n boolean markSupported()<\/span><\/td>\n To find out if the stream supports the mark() action, use this.<\/span><\/td>\n<\/tr>\n \n long skip(long n)<\/span><\/td>\n The character is skipped using it.<\/span><\/td>\n<\/tr>\n \n void unread (int c)<\/span><\/td>\n By copying the character to the pushback buffer, it is utilized to push the character back.<\/span><\/td>\n<\/tr>\n \n void unread (char[] cbuf)<\/span><\/td>\n It is used to push the character back by copying it to the pushback buffer.<\/span><\/td>\n<\/tr>\n \n void reset()<\/span><\/td>\n The stream is reset using it.<\/span><\/td>\n<\/tr>\n \n void close()<\/span><\/td>\n The stream is closed using it.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Constructor:<\/h3>\n
\n\n
\n Constructor<\/strong><\/td>\n Description<\/strong><\/td>\n<\/tr>\n \n PushbackReader(Reader in )<\/span><\/td>\n It creates a new pushback with one character pushback buffer.<\/span><\/td>\n<\/tr>\n \n PushbackReader (Reader in, int size)<\/span><\/td>\n It creates a new pushback with pushback with given size.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Example 1:<\/h4>\n
import java.io.*;\r\n\r\npublic class TechVidvan {\r\n public static void main(String[] args) throws Exception {\r\n char ary[] = {'1', '-', '-', '2', '-', '3', '4', '-', '5'};\r\n CharArrayReader reader = new CharArrayReader(ary);\r\n PushbackReader push = new PushbackReader(reader);\r\n\r\n int i;\r\n while ((i = push.read()) != -1) {\r\n if (i == '-') {\r\n int j;\r\n if ((j = push.read()) == '-') {\r\n System.out.print(\"#*\");\r\n } else {\r\n push.unread(j); \/\/ push back single character\r\n System.out.print((char) i);\r\n }\r\n } else {\r\n System.out.print((char) i);\r\n }\r\n }\r\n }\r\n}<\/pre>\nOutput:<\/strong>
\n1#*2-345<\/p>\nExample 2:<\/h4>\n
import java.io.*;\r\n\r\npublic class TechVidvan{\r\n public static void main(String[] args) {\r\n String s = \"TechVidvan\";\r\n\r\n StringReader sr = new StringReader(s);\r\n\r\n PushbackReader pr = new PushbackReader(sr, 20);\r\n\r\n try {\r\n for (int i = 0; i < 5; i++) {\r\n char c = (char) pr.read();\r\n System.out.print(\"\" + c);\r\n }\r\n\r\n System.out.println();\r\n\r\n pr.unread('A');\r\n\r\n char c = (char) pr.read();\r\n\r\n System.out.println(\"\" + c);\r\n\r\n pr.close();\r\n\r\n } catch (IOException ex) {\r\n ex.printStackTrace();\r\n }\r\n }\r\n}<\/pre>\nOutput:<\/strong><\/p>\n
TechV
\nA<\/p>\nExample 3:<\/h4>\n
import java.io.PushbackReader;\r\nimport java.io.StringReader;\r\npublic class TechVidvan\r\n{\r\n public static void main(String args[])\r\n {\r\n try\r\n { \r\n String str = \u201cWelcome to TechVidvan Java Tutorials\u201d; \r\n StringReader reader = new StringReader(str); \r\n PushbackReader pushbackReader = new PushbackReader(reader); \r\n System.out.println(\"pushbackReader ready: \" + pushbackReader.ready()); \r\n for (int i = 0; i < 9; i++) \t\r\n { \r\n char ch = (char) pushbackReader.read(); \r\n System.out.print(ch); \r\n pushbackReader.skip(1); \r\n } \r\n }\r\n catch (Exception e)\t{ \r\n System.out.print(\"Error: \"+e.toString());\r\n } \r\n }\r\n}<\/pre>\nOutput:<\/strong>
\npushbackReader ready: true
\nWloet ehi<\/p>\nConstructors:<\/h3>\n
\n
- PushbackReader(Reader push):<\/strong> Makes a new Pushback Reader and uses a character Pushback buffer to “push” it.<\/li>\n
- PushbackReader(Reader push, int size):<\/strong> Specifies the size of the pushback buffer when creating a new Pushback Reader.<\/li>\n<\/ul>\n
Benefits:<\/h3>\n
\n
- One or more characters can be returned to the input stream using the PushbackReader class. You can now see into the input stream thanks to this.<\/li>\n
- generates a buffered stream that permits the pushing back of a single character. bufSize is the size of the pushback buffer that is passed.<\/li>\n<\/ul>\n
Closing of PushBackReader:<\/h3>\n
\n
- It is important to remember to close the PushbackReader when you have completed reading the characters.<\/li>\n
- The Reader instance that a PushbackReader is reading from will also close when the PushbackReader is closed.<\/li>\n
- By using this to close: <\/strong>pushbackReader.close()<\/li>\n<\/ul>\n
Conclusion<\/h3>\n
We have learned about the PushbackReader details. It is used as a pushbackreader in the stream. This feature is handy for parsing scenarios where you may need to backtrack in the input stream.<\/p>\n","protected":false},"excerpt":{"rendered":"
Java is wide range and used in various applications. PushbackReader is discussed in a detailed manner. It allows characters to be pushed back into the Stream. The unread() method of this class allows us...<\/p>\n","protected":false},"author":6,"featured_media":447251,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[183],"tags":[296,351,352,299,263,250,353,5528,354,355,5646],"class_list":["post-89857","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-java","tag-java-pushbackreader","tag-java-pushbackreader-class","tag-java-tutorial","tag-java-tutorial-for-beginners","tag-learn-java","tag-pushbackreader","tag-pushbackreader-class","tag-pushbackreader-class-in-java","tag-pushbackreader-in-java","tag-pushbackreader-in-java-with-examples"],"yoast_head":"\n
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