如何调试始终在java（eclipse）中运行的程序？

我是java的初学者，有一个程序一直在运行，没有错误报告。请帮助我如何调试这个问题？我想使用Scanner类随机打印一个大写字母

import java.nio.CharBuffer;
import java.util.Random;
import java.util.Scanner;
class SequenceChar{
private static Random rand  = new Random(47);
private static final char[] capitals = 
        "ABCDE".toCharArray();
char generate(){
    char buffer;
    int idx = 0;
    buffer = capitals[rand.nextInt(capiticals.length)];
    return buffer;
    }
}

public class C8 extends SequenceChar 
 implements Readable{
private int i;
public C8(int i){
    this.i = i;
}
public int read(CharBuffer ch){
    char buffer = generate();
    ch.put(buffer);

    return buffer;
}
public static void main(String[] args) {
    Scanner output  = new Scanner (new C8(103));

    System.out.println("begin");
    while(output.hasNext()){

        System.out.println(output.next());
    }
    System.out.println("end");


   }

 } 

Output.hasNext（）正在返回“True”。如果只想打印一个单词，请不要使用循环。用“如果”代替

查找“断点”。同时

while(output.hasNext())

if(output.hasNext()){

        System.out.println(output.next());
    }