Find and Replace Occurencies of a String In the same file

Description:
You need to replace all occurencies of a string in a text file

Solution: (For Java 1.4 and higher)

Use the following method:

public static void readReplace(String fname, String oldPattern, String replPattern){
	String line;
	StringBuffer sb = new StringBuffer();
	try {
		FileInputStream fis = new FileInputStream(fname);
		BufferedReader reader=new BufferedReader ( new InputStreamReader(fis));
		while((line = reader.readLine()) != null) {
			line = line.replaceAll(oldPattern, replPattern);
			sb.append(line+"\n");
		}
		reader.close();
		BufferedWriter out=new BufferedWriter ( new FileWriter(fname));
		out.write(sb.toString());
		out.close();
	}
	catch (Throwable e) {
	            System.err.println("*** exception ***");
	}
}

The method reads a file line by line, replaces a string in each line if any, appends the resulting line to a StringBuffer. After all the file has been read to a StringBuffer, it is written to the same file. The argumens to the String.replaceAll method must follow the regular expression pattern rules.

Usage:
readReplace("filename.txt", "Russia", "China");

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