Find and Replace in File in Java: Explanation & Practice

Problem summary

Replace all occurrences of a word in a file with another word.

Starter code

import java.io.*;

public class Main {
    public static void main(String[] args) {
        String find = "old";
        String replace = "new"; // Test case 1
        
        // Replace all occurrences
        // Print: Replaced <count> occurrences
    }
}

Expected output and test cases

• 5 replacements made

  Replaced 5 occurrences

• Word not found

  Replaced 0 occurrences

• Many replacements

  Replaced 10 occurrences

Hints

1. Read entire file content
2. Use String.replace() or replaceAll()
3. Count occurrences before replacing

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• Practice File Statistics in Java
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• Practice Log File Parser in Java

Practice all File I/O exercises · Run this idea in the Java compiler