Need a dynamic programmatic file header generator? Try this out!

HeaderGenerator.java

import java.util.LinkedHashMap;
import java.util.Map;

public class HeaderGenerator {
    private Map<String, String> map = new LinkedHashMap<String, String>();
    private String separator = ": ";
    private int indentation_size = 4;
    private char indentation_char = ' ';
    private int padding_size = 1;
    private char border_char = '/';
    private int border_size = 2;
    
    public void clear() {
        map.clear();
    }
    
    public String generate() {
    	int size = 0;
    	
        for (final String key : map.keySet()) {
             final String val = map.get(key);
             
             final int size_temp = (key + this.getSeparator() + val).length();
             
             if(size_temp > size)
            	 size = size_temp;
        }
        
        final String x_border = new String(new char[size + (this.getBorderSize() * 2) + (this.getPaddingSize() * 2)]).replace('\0', this.getBorderChar());
        final String indentation = new String(new char[this.getIndentationSize()]).replace('\0', this.getIndentationChar());
        
        final StringBuilder builder = new StringBuilder();
        builder.append(indentation).append(x_border).append("\n");

        //for(int i = 0; i < this.getBorderSize(); i++) // this code is for y-border size
        	//builder.append(indentation).append(x_border).append("\n");
        
        builder.append(indentation);
        for(int i = 0; i < this.getBorderSize(); i++)
        	builder.append(this.getBorderChar());
        for(int i = 0; i < size + (this.getPaddingSize() * 2); i++)
        	builder.append(" "); // filler
        for(int i = 0; i < this.getBorderSize(); i++)
        	builder.append(this.getBorderChar());
        builder.append("\n");
        
        for (final String key : map.keySet()) {
            final String val_ = map.get(key);
            
            final String[] split = val_.split("\n");
            for(final String val : split) {
	            final int size_temp = (key + this.getSeparator() + val).length();
	            builder.append(indentation);
	            for(int i = 0; i < this.getBorderSize(); i++)
	            	builder.append(this.getBorderChar());
	            for(int i = 0; i < this.getPaddingSize(); i++)
	            	builder.append(" "); // padding_char
	            
	            builder.append(key + this.getSeparator() + val);
	            
	            final int left_over = size - size_temp;
	        	for(int i = 0; i < left_over; i++)
	        		builder.append(" "); // filler

	            for(int i = 0; i < this.getPaddingSize(); i++)
	            	builder.append(" "); // padding_char
	            for(int i = 0; i < this.getBorderSize(); i++)
	            	builder.append(this.getBorderChar());
	            
	            builder.append("\n");
            }
        }
        
        builder.append(indentation);
        for(int i = 0; i < this.getBorderSize(); i++)
        	builder.append(this.getBorderChar());
        for(int i = 0; i < size + (this.getPaddingSize() * 2); i++)
        	builder.append(" "); // filler
        for(int i = 0; i < this.getBorderSize(); i++)
        	builder.append(this.getBorderChar());
        builder.append("\n");
        
        builder.append(indentation).append(x_border);
        
        return builder.toString();
    }
    
    public boolean set(final String key, final String val) {
        final boolean exists = map.containsKey(key);
        
        map.put(key, val);
        
        return exists;
    }
    
    public String get(final String key) {
        return map.getOrDefault(key, null);
    }
    
    public Map<String, String> getMap() {
        return map;
    }
    
    public String getSeparator() {
    	return this.separator;
    }
    
    public void setSeparator(final String separator) {
    	this.separator = separator;
    }

	public int getIndentationSize() {
		return indentation_size;
	}

	public void setIndentationSize(final int indentation_size) {
		this.indentation_size = indentation_size;
	}

	public char getIndentationChar() {
		return indentation_char;
	}

	public void setIndentationChar(final char indentation_char) {
		this.indentation_char = indentation_char;
	}

	public int getPaddingSize() {
		return padding_size;
	}

	public void setPaddingSize(final int padding_size) {
		this.padding_size = padding_size;
	}

	public char getBorderChar() {
		return border_char;
	}

	public void setBorderChar(final char border_char) {
		this.border_char = border_char;
	}
	
	public int getBorderSize() {
		return this.border_size;
	}
	
	public void setBorderSize(final int border_size) {
		this.border_size = border_size;
	}
}

Main.java

import com.arinerron.utils.appheadergenerator.HeaderGenerator; // The main package
import java.util.Date; // just for this example

public class Main {

	public static void main(String[] args) {
		HeaderGenerator gen = new HeaderGenerator(); // Create a new header generator instance
		gen.clear(); // Remove all entries from the header
		gen.set("Author", "Arinerron"); // Add a value and key
		gen.set("Message", "Try this program out!"); // example
		gen.set("Date", new Date().toString()); // yet another example
		gen.setBorderChar('|'); // The character that the border is made up of
		gen.setBorderSize(2); // The number of border characters on each side
		gen.setPaddingSize(6); // The number of padding characters to the left of each line
		gen.setPaddingChar(' '); // The character of the padding that is printed
		
		String header = gen.generate(); // Create the header
		System.out.println(header); // Check it out! :)
		
		// I didn't document the `get` functions, but just assume that you can replace all of the `set` functions above with `get`.
	}
}