Java Fundamentals Quiz

Please write down the definition of identifiers.

must be the beginning of the letter, consisting of letters, numbers, underscores, and$

Determine if the following identifiers are correct:

1yyy_o (wrong)

Demo02 (right)

Abc$2 (right)

Class (yes)

Text!p (wrong)

Please calculate How many bits50MB is?

1024*1024*8*50

Please write down eight basic data types

Byte,short,int,long,double,float,boolean,char

Please write down the reference data type you know

Scanner,random,string

Write a program to find 1+3+5+7+......+99 and Values

int sum = 0;
for (int i =0;i<100;i++) {
if (i%2!=0) {
sum = sum+i;
}
}
SYSTEM.OUT.PRINTLN (sum);

output of all narcissus numbers, the so-called Narcissus number refers to a number 3 digits, its per digit cubic and equal to itself , such as 153 = 1*1*1 + 3*3*3 + 5*5*5

 for (int i=100;i<1000;i++) {        int a = i/100;         int b = (I/10)%10;         int c = i%10;         if (a*a*a+b*b*b+c*c*c==i) {            System.out.println (i);        }    }

Printing 9*9 tables with A For loop

 for (int i=1;i<9;i++) {            for (int j=1;j<=i;j++) {                System.out.print (J+ "*" +i+ "=" +j*i+ "\ T");            }            System.out.println ();        }

Defines a method for printing array elements, printing in a given format [11, 33, 44, 22, 55]

int [] ARRT ={11,33,44,22,55};              for (int i =0;i<arrt.length;i++) {                System.out.printl (arrt[i]);

Existing array arr[6,9,4,6,2,5,8], output array elements in reverse order

int [] ARRT ={6,9,4,6,2,5,8};          for (int i=arrt.length-1;i>0;i--) {            System.out.println (arrt[i]);        }

A two-dimensional array traversal gets to each value

int [] Intarr = {{12,3,8},{11,8,32,7},{13,44,55}};     int [] arr = {{12,3,8},{11,8,32,7},{13,44,55}};          for (int i= 0;i<arr.length;i++) {            for (int j=0;j<arr[i].length;j++ ) {                System.out.println (arr[i][j]);            }        }

Company Annual Sales sum

the data for a company by quarter and month are as follows: Unit ( million Yuan )

First quarter:22,66,44

second quarter:77,33,88

third quarter:25,45,65

fourth quarter:11,66,99

int [] arr ={{22,66,44},{77,33,88},{25,45,65},{11,66,99}};         int sum = 0;          for (int i=0;i<arr.length;i++) {            for (int j=0;j<arr[i].length;j++ {                = sum+arr[i][j];            }        }

define a student class Student, which contains three attribute names, age, and gender, creates three student objects to be stored in a ArrayList collection.

A: Iterates through the set traversal output.

B: Find the oldest student, let the name of the object become: Gourd Doll.

1Arraylist<stu> stu =NewArraylist<stu>();2Stu arr1 =NewStu ();3Stu arr2 =NewStu ();4Stu Arr3 =NewStu ();5Arr1.name= "Wang Rongshen";6Arr1.age = 23;7Arr1.sex = "Male";8 Stu.add (arr1);9Arr2.name = "Zhang Rui";TenArr2.age = 26; OneArr2.sex = "Male"; A Stu.add (ARR2); -Arr3.name = "Director"; -Arr3.age = 25; theArr3.sex = "Male"; - Stu.add (ARR3); -          for(intI=0;i<stu.size (); i++){ -System.out.println (Stu.get (i). name+ "\ T" +stu.get (i). age+Stu.get (i). Sex); +         } -         intA= Stu.get (0). Age; +          for(intI=0;i<stu.size (); i++){ A             if(Stu.get (i) .age>a) { atA=Stu.get (i). Age; -             } -         } -              for(intI=0;i<stu.size (); i++){ -             if(Stu.get (i). age==a) { -Stu.get (i). Name = "Gourd Doll"; in             } - System.out.println (Stu.get (i). name); to         }     +     } -}

Java Fundamentals Quiz