编写java程序 编写三个线程，一个线程输出a~z，一个线程输出A~Z，一个线程输出1~26。

public class PrintThread extends Thread {
    private final int start;
    private final int end;

    public PrintThread(int start, int end) {
        this.start = start;
        this.end = end;
    }

    @Override
    public void run() {
        for (int i = start; i <= end; i++) {
            System.out.print((char) (i + 'A' - 1));
        }
    }
}

public class Main {
    public static void main(String[] args) {
        PrintThread thread1 = new PrintThread(1, 26);
        PrintThread thread2 = new PrintThread(27, 52);
        PrintThread thread3 = new PrintThread(65, 90);

        thread1.start();
        thread2.start();
        thread3.start();
    }
}