Generate power print

Replicate.java

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
import java.util.ArrayList;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Replicate {
    public static void main(String []args) throws IOException, InterruptedException {
	int n = 3;
	List<String> ls = new ArrayList<String>();
	ls.add("public class Gen {");
	ls.add("\tpublic static void main(String []args) {");
	for (int i = 0; i < n; i++) {
	    ls.add("for(int i"+i+" = 0; i"+i+" < "+n+"; i"+i+"++) {");
	}
	ls.add("System.out.print('A');");
	for (int i = 0; i < n; i++) {
	    ls.add("}");
	}
	ls.add("\t}");
	ls.add("}");

	Files.write(Paths.get("Gen.java"), ls);
	Process child = Runtime.getRuntime().exec("javac Gen.java");
	child.waitFor();
	child = Runtime.getRuntime().exec("java Gen");
	BufferedReader in = new BufferedReader(new InputStreamReader(child.getInputStream()));
	int c = -1;
	while ((c = in.read()) != -1) {
	    System.out.print((char)c);
	}
	System.out.println();
    }
}