创建两个线程，要求如下： （1）一个线程输出100个1~26，另一个线程输出100个A~Z。 （2）一个线程使用集成Thread 类的写法，另一个线程使用实现Runnable接口的写法。

好的，下面是代码实现：

1. 继承Thread类的写法

class PrintNumberThread extends Thread {
    @Override
    public void run() {
        for (int i = 1; i <= 100; i++) {
            for (int j = 1; j <= 26; j++) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}

class PrintLetterThread extends Thread {
    @Override
    public void run() {
        for (int i = 1; i <= 100; i++) {
            for (char j = 'A'; j <= 'Z'; j++) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}

public class MultiThreadDemo {
    public static void main(String[] args) {
        PrintNumberThread numberThread = new PrintNumberThread();
        PrintLetterThread letterThread = new PrintLetterThread();

        numberThread.start();
        letterThread.start();
    }
}

2. 实现Runnable接口的写法

class PrintNumberRunnable implements Runnable {
    @Override
    public void run() {
        for (int i = 1; i <= 100; i++) {
            for (int j = 1; j <= 26; j++) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}

class PrintLetterRunnable implements Runnable {
    @Override
    public void run() {
        for (int i = 1; i <= 100; i++) {
            for (char j = 'A'; j <= 'Z'; j++) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}

public class MultiThreadDemo {
    public static void main(String[] args) {
        PrintNumberRunnable numberRunnable = new PrintNumberRunnable();
        PrintLetterRunnable letterRunnable = new PrintLetterRunnable();

        Thread numberThread = new Thread(numberRunnable);
        Thread letterThread = new Thread(letterRunnable);

        numberThread.start();
        letterThread.start();
    }
}

希望这个例子可以帮助你理解Java多线程中的一些概念。