java read file to StringBuilder code example

Example: load contents of file into string java

package test;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;


/**
 * Java Program to demonstrate different ways to loop over collection in 
 * pre Java 8 and Java 8 world using Stream's forEach method.
 * @author Javin Paul
 */
public class FileToStringJava8 {

    public static void main(String args[]) throws IOException {

        // How to read file into String before Java 7
        InputStream is = new FileInputStream("manifest.mf");
        BufferedReader buf = new BufferedReader(new InputStreamReader(is));
        
        String line = buf.readLine();
        StringBuilder sb = new StringBuilder();
        
        while(line != null){
            sb.append(line).append("\n");
            line = buf.readLine();
        }
        
        String fileAsString = sb.toString();
        System.out.println("Contents (before Java 7) : " + fileAsString);
        
        
        // Reading file into Stirng in one line in JDK 7
        String contents = new String(Files.readAllBytes(Paths.get("manifest.mf")));
        System.out.println("Contents (Java 7) : " + contents);
        
        
        
        // Reading file into String using proper character encoding
        String fileString = new String(Files.readAllBytes(Paths.get("manifest.mf")), StandardCharsets.UTF_8);
        System.out.println("Contents (Java 7 with character encoding ) : " + fileString);
        

        // It's even easier in Java 8
        Files.lines(Paths.get("manifest.mf"), StandardCharsets.UTF_8).forEach(System.out::println);
        
    }


}