Java1-1507064134

[InnoFang]

作业1：删羊

方法一：用迭代器来删除后面三只羊
    public void iteratorForRemove() {
        Iterator<Sheep> it = sheepList.iterator();
        int a = sheepList.size() - 1;
        int i = 0;
        while (it.hasNext()) {
            Sheep sheep = (Sheep) it.next();
            if (i > a - 3) {
                it.remove();
            }
            i++;
        }
    }
方法二：用普通for循环来删除后面三只羊
    public void forForRemove() {
        int a = sheepList.size() - 1;
        for (int i = sheepList.size() - 1; i > a - 3; i--) {
            sheepList.remove(i);
        }
    }
方法三：用foreach来删除后面三只羊
    public void foreachForRemove() {
        for (Sheep sh : sheepList) {
            if (i > a - 3) {
                sheepList.remove(sh.name);
            } else {
                System.out.print(sh.name+" ");
            }
            i++;
        }
    }

作业2：自动写文件

File fe = new File("D://testforio");
        try{
        if(!fe.exists()){
            fe.mkdir();
        }
        FileOutputStream fos = null;
        File file = null;
        for(int i = 1;i <= 10;i++){
            file = new File(fe,"HelloWorld"+i+".txt");
            fos = new FileOutputStream(file);
            if(!file.exists()){
                file.createNewFile();
            }
            String str ="我真 "+i;
            byte[]  b = str.getBytes();
            fos.write(b);
            fos.flush();
            fos.close();
        }
    }catch(IOException  e){
        e.printStackTrace();
    }

作业3.用代码实现比较Runnable和Thread的区别

class ThreadExtend implements Runnable{
    int i = 5;
    public void run(){
        while(i > 0){
            System.out.println(Thread.currentThread().getName()+"得到"+i);
            i--;
        }
    }
}
public class MyRunnable {
    public static void main(String[] args) {    
        ThreadExtend te = new ThreadExtend();
        Thread h1 = new Thread(te,"first");
        Thread h2 = new Thread(te,"second");
        Thread h3 = new Thread(te,"third");
        Thread h4 = new Thread(te,"fourth");
        h1.start();
        h2.start();
        h3.start();
        h4.start();
    }
}


class ThreadExtend extends Thread{
    String name;
    public ThreadExtend(String name){
        this.name = name;
    }
    int i = 5;
    public void run(){
        while(i > 0){
            System.out.println(name+"得到"+i);
            i--;
        }
    }
}
public class MyThread {
    public static void main(String[] args) {
        ThreadExtend h1 = new ThreadExtend("first");
        ThreadExtend h2 = new ThreadExtend("second");
        ThreadExtend h3 = new ThreadExtend("third");
        ThreadExtend h4 = new ThreadExtend("fourth");
        h1.start();
        h2.start();
        h3.start();
        h4.start();
    }
}

• 区别
  • 由于Java单继承特性导致了每一个类只能继承一个类，若继承了Thread类则无法继承别的类，而Runnable是接口，所以Runnable方式可以避免Thread方式由于Java单继承特性带来的缺陷
  • Runnable的代码可以被多个线程（Thread实例）共享，适合于多个线程处理同一个资源的情况。