1. Data type variable name = value;
Eg:
Double score = 15.65;
String name = "Zhang San";
Char sex = "male";
Data type variable name = (data type) value;
Example:
Double num=15.75;
int sum = (int) num;
Results: sum=15;
Chapter III 1. If selection structureSyntax: if (condition) {
code block//After the condition is established, it can be a statement or a set of statements
}
Example:
If (7>5) {
System.out.println ("true");
}
Syntax: if (condition) {
Code Block 1
}else{
Code Block 2
}
Example:
if (chengji>98) {
System. out. println ("Teacher said: Yes, reward a mp4");
}Else {
System. out. println ("teacher says: Code penalty!!!" ");
}
3. multiple if selection structureSyntax: if (condition 1) {
Code Block 1
}else if (condition 2) {
Code Block 2
}else{
Code block 3
}
Example:
if (qian>=500) {
System. out. println ("Great, I can buy a Cadillac");
}Else if (qian>=100) {
System. out. println ("Also, I can sell a Passat");
}Else if (qian>=10) {
System. out. println ("I can buy an Austrian extension");
}Else if (qian>=5) {
System. out. println ("I can buy a Elantra");
}Else{
System. out. println ("It seems that I can buy a Czech own");
}
4. nested IF selection structureGrammar:
if (condition 1) {
if (condition 2) {
Code Block 1
}else{
Code Block 2
}
}else{
Code block 3
}
Example:
if (chengji<=10) {
if (Xingbie.equals ("male")) {
System. out. println ("Enter the men's group final");
}Else if(xingbie.equals ("female")) {
System. out. println ("Enter the women's group Finals");
}
}Else{
System. out. println ("obsolete!!!!");
}
Fourth Chapter1. Switch Selection structureSyntax: switch (condition) {
CASE constant 1:
code block 1;
Break
Case constant 2:
code block 2;
Break
......
Default
code block N;
Break
}
Example:
Switch (MINGCI) {
Case 1:
System. out. println ("Attend the one-month summer camp organized by MIT");
break;
Case 2:
System. out. println ("Reward hp notebook PC");
break;
Case 3:
System. out. println ("Reward mobile HDD One");
break;
default:
System. out. println ("no Rewards");
break;
}
Fifth Chapter1. While loop structureSyntax: while (loop condition) {
Looping operations
}
Example:
int i = 1;
while (i<=100) {
System.out.println ("Struggle hard");
i = i + 1;
}
2. Do-while Cycledo{
Looping operations
}while (cyclic operation);
Example:
int i = 1;
do{
System.out.println ("Fight hard!")
i++;
}while (i<=100);
Sixth Chapter1. For LoopGrammar:
for (expression 1; expression 2; expression 3) {
Loop body
}
Example:
for (I=0, j=num;i<=num;i++,j--) {
System. out. println (i+ "+" +j+ "=" + (i+j));
}
Example:
for (int i =0;i<5;i++) {
System. out. println ("Please enter" + (i + 1) + "Gate score:");
Score = Input.nextint ();
if (score<0) {
Isnegative = true;
break;
}
Example:
for (int i = 0;i<totle;i++) {
System. out. println ("Please enter" + (i+1) + "Student's score:");
Score =input.nextint ();
if (score<80) {
continue;
}
Eighth Chapter1. Declaring an array
Grammar:
data type [] array name; or data array name [];
Example:
Int[] Scres;
2, allocating space
Grammar:
Array name = new data type [array length];
Example:
Scores = new INT[10];
Integrated approach:
data type [] Array name = new data type [array length];
Example:
int scores[] = new int[10];//stores 10 data points
Watch out! Once the size of the array is declared, it cannot be modified. That is, the length of the array is fixed,
3. Assigning values
After allocating space, you can store the data in the array, and each element in the array is accessed by subscript.
Grammar:
Array name [subscript value];
Example:
To store data in an scores array
Scores[0] = 10;
Grammar:
data type [] Array name ={value 1, value 2, value 3,......... Value n};
Example:
int [] scores = {30.20.10,60.78};
Can also be written as:
Int[] scores = new int[]{30,20,10,60,78};
4. Array Sorting
Syntax: Arrays.sort (array name);
Example:
max = Scores[0];
for (int i = 1;i<scores.length;i++) {
if (Scores[i]>max) {
max = Scores[i];
}
Example:
for (int i =0;i<list.length;i++) {
if (Num>list[i]) {
index = i;
Break
}
}
Element move back
for (int j = list.length-1;j>index;j--) {
List[j]= List[j-1];//index The element that starts with the subscript moves back one position
1. Syntax://while and while loop nesting
while (loop condition 1) {
Circular Operation 1
while (loop condition 2) {
Circular Operation 2
}
}
Example:
Int i=0;
Int j=0;
while (i<3) {
while (j<3) {
System.out.println ("Fight hard!");
j + +;
}
i++;
}
2.//do-while and Do-while loop nesting
bo=
Circular Operation 1
bo=
Circular Operation 2
}while (cycle condition 2);
}while (cycle condition 1)
Example:
Int i=0;
Int j=0
do{
do{
System.out.println ("Fight hard!");
j + +;
}while (j<3)
i++;
}while (i<3)
3.//for and for loop nesting
for (loop condition 1) {
Circular Operation 1
for (loop condition 2) {
Circular Operation 2
}
}
Example:
for (int i = 0; i < average.length; i++) {
sum=0.0;
System. out. println ("Please enter the" + (i+1) + "Grade of the Class");
for (int j = 0; J < Score.length; J + +) {
System. out. println ("First" + (J+1) + "scores of participants");
Score[j]=input.nextint ();
SUM+=SCORE[J];
}
Average[i]=sum/score.length;
System. The average score of println ("i+1" + "class entry Academy" is "+average[i]+" \ n ");
}
4.//while with For loop nesting
while (loop condition 1) {
Circular Operation 1
for (loop condition 2) {
Circular Operation 2
}
}
Example:
for (int i=1;i<num;i++{
while (B[0]!=a[i]) {
B[1]=a[i];
count++;
Break
find = true;
}
if (find)
Break
}
Grammar:
public class < class name > {
}
Example:
public class School {
String Schoolname;
int classnumber;
int labnumber;
Grammar:
Access modifier return value type method name () {
Method body
}
Example:
public void Showcenter () {
SYSTEM.OUT.PRINTLN (schoolname+ "Training center \ n" + "equipped with:" +classnumber+ "classroom" +labnumber+ "machine");
}
3. How to create and use objectsSyntax for creating objects:
Class Name Object name = new class name ();
Example:
School Center = new School ();
The name of the object. Properties//referencing properties of an object
The name of the object. Method Name//method of referencing object
Example:
center.name = "Beijing Center"; Assigning a value to the Name property
Center.showcenter (); Call the Showcenter () method
12th Chapter 1. How to define a class methodGrammar:
Public return value type method name () {
The body of the method
}
Grammar:
return expression;
Example:
Public String robball{
String ball = "one";
return ball;
14th Chapter1. Defining the Parameter method
Syntax:< access modifier > Return value type < method name > (< parameter list >) {
Method body
}
Example: public void Show (String name,int age) {
}
15th ChapterString name= "Zhang San";
1. Get the length of a string
Syntax: Length ();
Example:
Name.length ();
2. Comparing strings
Syntax: Equals ();
Example:
Name.rquals ("Zhang San")
3. Connection string
Syntax: Concat ();
Example:
Name.concat ("18 years old");
4. Extracting a String
Syntax: substring ();
Example:
Name.substring (0); Extract No. 0 bit
5. Searching for strings
Syntax: IndexOf ();
Example:
Name.indexof (1); Returns the value of the 1th bit
6. Splitting a string
Syntax: Split (String separator,int limit);
Example:
String ci = "changting outside the ancient road edge";
Chai =ci.split (""); Split by Space
7. Remove the leading and trailing spaces
Syntax: Trim ();
Example:
Name.trim ();
StringBuffer
8. Convert to String type
Syntax: toString ();
Example:
StringBuffer a =new stringbuffer ("ABCDEFG");
A.tostring ();
9. Connection string
Syntax: Append ();
Example:
StringBuffer a =new stringbuffer ("ABCDEFG");
A.append ("Hijk");
10. Inserting a string
Syntax: Insert ();
Example:
StringBuffer a =new stringbuffer ("ABCDEFG");
for (int i=a.length () -3;i>0;i=i-3) {
A.insert (i, ', ');
}
"Java Syntax example 2~15 chapter"
Start building with 50+ products and up to 12 months usage for Elastic Compute Service
1 on 1 presale consultation
24/7 Technical Support 6 Free Tickets per Quarter Faster Response
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.
A comprehensive suite of global cloud computing services to power your business
Payment Methods We Support
