第四百九十七天 how can I 坚持

@Test
    public void DerviedTest(){
        Dervied derive=new Dervied();
        derive.tellName();
        System.out.println(0.0/0); //输出NaN
        System.out.println(0.0f/0);//输出NaN
        System.out.println(0.0f/0.0d);//输出NaN
//        System.out.println(0/0);//报异常
//        System.out.println(derive.getValue(2)+"");
        System.out.println(((Double)null).NaN);//输出NaN
        double d1=Double.NaN;
        double d2=Double.NaN;
        if(d1>d2||d1<=d2){
            System.out.println("true");
        }else{
            System.out.println("false");
        }//好神奇 计算机的世界啊
    }
    @Test
    public void Test01(){
        int result=0;
        int i=2;
        switch(i){
        case 1:
            result=result+i*1;
        case 2:
            result=result+i*2;
        case 3:
            result=result+i*3;
        }
        System.out.println(result);//输出10 因为没有break
    }
    @Test
    public void Test03(){
        int i=1231231231;
        int j=-1231231231;
        System.out.println(i-j);//内存溢出
    }

public class NULL {
    public static void haha(){
        System.out.println("haha");
    }
    public static void main(String args[]){
        ((NULL)null).haha();//null可以转化为任意对象，然后调静态方法。
    }
}

public class Dervied extends Base{
    private String name = "dervied";
    public Dervied() {
        tellName();
        printName();
    }
    public void tellName() {
        System.out.println("Dervied tell name: " +name);
    }
    public void printName() {
        System.out.println("Dervied print name: " +name);
    }
    public static void main(String[] args){
        new Dervied();
        /**输出结果是：
        Dervied tell name: null
        Dervied print name: null
        Dervied tell name: dervied
        Dervied print name: dervied
        */
    }
}
class Base {
    private String name = "base";
    public Base() {
        tellName();
        printName();
    }
    public void tellName() {
        System.out.println("Base tell name: " +name);
    }
    public void printName() {
        System.out.println("Base print name: " +name);
    }
}