1.How it works: the juicer throws an apple into the juicer, out of the apple juice; throws a peach in and out of the peach juice; throws a pear in and out of the pear juice. (fruit is the parameter, juice is the return value).
Give an example:
package demo2;
public class Zhazhiji {
//“
public String zhazhi(String fruit){
String juice=null;
if (fruit.equals(“apple”)) {
juice=”apple juice”;
}else if(fruit.equals(“peach”)){
juice=”peach juice”;
}else if(fruit.equals(“pear”)){
juice=”pear juice”;
}
return juice;
}
}
package demo2;
public class ZhaizhijiTest {
public static void main(String[] args) {
Zhazhiji zz=new Zhazhiji();
String juice=zz.zhazhi(“peach”);
System.out.println(juice);
}
}
2.package demo2;
public class Zhazhziji1 {
public String zhazhi(String fruit){
String juice=fruit+”“;
return juice;
}
}
package demo2;
public class test {
public static void main(String[] args) {
Zhazhziji1 zz=new Zhazhziji1();
String juice=zz.zhazhi(““);
System.out.println(juice);
}
}
1. > access modifier> <>(<>) {
// method
}
public class StudentsBiz {
String[ ] names = new String[30];
public void addName(String name) {
//}
public void showNames() { // shows the names of all students.}
}
2..1, parameters2,n
Give an example:
public static void main(String[] args) {
StudentsBiz st = new StudentsBiz(); First instantiate objects, then use them.
Scanner input = new Scanner(System.in);
for(int i=0;i<5;i++){
System.out.print(““);
String newName = input.next;
st.addName(newName);
st.addName(newName);
}
st.showNames();
}
3.Give an example:
package demo3;
public class StudentBiz {
public String[] students=new String[6]; //public void add(String name){
for (int i = 0; i < students.length; i++) {
if (students[i]==null) { students[i]=name;
break;
}
}
}
//public void show(){
for (int i = 0; i < students.length; i++) {
System.out.println(students[i]+”\t”);
}
}
//public boolean find(int begin,int end,String name){
boolean rs=false;
for (int i = begin; i < end; i++) {
if (students[i].equals(name)) {
rs=true;
break;
}
}
return rs;
}
}
package demo3;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
StudentBiz sbz=new StudentBiz();
//for (int i = 0; i < sbz.students.length; i++) {
System.out.println(“ >“+(i+1)+”“);
String name=input.next();
sbz.add(name);
}
// shows all student information.
for (int i = 0; i < sbz.students.length; i++) {
System.out.println(sbz.students[i]);
}
//System.out.println(““);
String findName=input.next();
boolean rs=sbz.find(1, 4, findName);
if (rs) {
System.out.println(“success”);
}else{
System.out.println(“fail”);
}
}
}
4. > taking ginseng
1.//public void addName(String name){
//}
//“) >;
2. //public boolean searchName(int start ,int end ,String name){
//}
//String s=”“;
int e=3;
String name=”“;
boolean flag=. searchName(s ,e ,name)
Method calls are formal arguments without actual values.
When it is called, it is the actual parameter.
3.//public boolean searchName(int start,int end,String name){
//}
//int s=1;
int e=3;
boolean flag= .searchName(s,e);
4.//public boolean searchName(int start,int end,String name){
//}
//int s=1;
int e=3;
String name=”“;
package zuoye;
public class editName {
public String[] customer=new String[5];
//public void add(String name){
for (int i = 0; i < customer.length; i++) {
if (customer[i]==null) {
customer[i]=name;
break;
}
}
}
//public boolean editName(String oldName,String newName){
boolean find=false;
for (int i = 0; i <customer.length ; i++) {
if (customer[i].equals(oldName)) {
customer[i]=newName;
find=true;
break;
}
}
return find;
}
//public void show(){
System.out.println(“*****************”);
System.out.println(““);
System.out.println(“*****************”);
for (int i = 0; i < customer.length; i++) {
System.out.print(customer[i]+”\t”);
}
System.out.println();
}
}
package zuoye;
import java.util.Scanner;
public class editNameTest {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
//editName a=new editName();
for (int i = 0; i < a.customer.length; i++) {
System.out.print(“:”);
String name=input.next();
a.add(name);
}
//a.show();
//System.out.println(““);
String oldName=input.next();
System.out.println(““);
String newName=input.next();
System.out.println(“**********”);
boolean rs=a.editName(oldName,newName);
if(rs){
System.out.println(““);
}else{
System.out.println(““);
}
/*if (a.editName(oldName,newName)) {
System.out.println(““);
}else{
System.out.println(““);
}
*/
a.show();
}
}
5.Give an example:
public class Mark {
/**/
public double calcMax(double[] marks){ double max=0;
for (int i = 0; i < marks.length; i++) {
if (marks[i]>max) {
max=marks[i];
}
}
return max;
}
/**/
public double calcAvg(double[] marks){
double sum=0;
double avg=0;
for (int i = 0; i < marks.length; i++) {
sum=sum+marks[i];
}
avg=sum/marks.length;
return avg;
}
}
public class MarksTest {
public static void main(String[] args) {
double[] marks={10,20,30,40,50,60,70,80,90,100};
Mark m=new Mark();
double max=m.calcMax(marks);
double avg=m.calcAvg(marks);
System.out.println(“max”+max);
System.out.println(“avg”+avg);
}
}
Mind:
6. objects in Song body as parameters
Multiple related information can be encapsulated into objects and passed as parameters to avoid too many parameters.
package ;
public class Student {
/*public String name;
public int age;
public double mark;
public String id;
/**/
public void info(){
System.out.println(““+name+”“+age+”“+mark+”“+id);
}
}
package ;
/**/
public class StudentBiz2 {
/**/
public Student[] students=new Student[5];
/* */
public void save(Student stu){
for (int i = 0; i < students.length; i++) {
if (students[i]==null) {
students[i]=stu;
break;
}
}
}
/*
* id
* * */
public Student find(String id) {
Student s=null;//“
for (int i = 0; i < students.length; i++) {
if(students[i].id.equals(id)) {
s=students[i];
break;
}
}
return s;
}
/* shows all student information.*/
public void show(){
System.out.println(“************************”);
System.out.println(“\t\t\t“);
for (int i = 0; i < students.length; i++) {
System.out.println(students[i].id+”\t\t”+students[i].name+”\t\t”+students[i].mark+”\t\t”+students[i].age);
}
System.out.println(“************************”);
}
/* */
public boolean editStudent(Student s){
boolean find=false;
for (int i = 0; i <students.length ; i++) {
if (students[i].id.equals(s.id)) {
students[i].name=s.name;
students[i].age=s.age;
students[i].mark=s.mark;
find=true;
break;
}
}
return find;
}
}
package ;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
StudentBiz2 sbz=new StudentBiz2();
//for (int i = 0; i < sbz.students.length; i++) {
Student s=new Student();
System.out.println(“ >“+(i+1)+”“);
System.out.println(““);
s.id=input.next();
System.out.println(““);
s.name=input.next();
System.out.println(““);
s.age=input.nextInt();
System.out.println(““);
s.mark=input.nextDouble();
sbz.save(s);
}
// shows all student information.
sbz.show();
//id System.out.println(“id”);
String id=input.next();
Student stu=sbz.find(id);
stu.info();
//Student sEdit=new Student();
System.out.println(““);
sEdit.id=input.next();
System.out.println(““);
sEdit.name=input.next();
System.out.println(““);
sEdit.age=input.nextInt();
System.out.println(““);
sEdit.mark=input.nextDouble();
boolean rs=sbz.editStudent(sEdit);
if(rs){
System.out.println(“success”);
}else{
System.out.println(“fail !“);
}
// sbz.show();
}
}
Exercise: sorting customer names
package paixu;
import java.util.Arrays;
public class SortName {
public void sortN(String[] str){
System.out.println(“…”);
for (int i = 0; i < str.length; i++) {
System.out.print(str[i]+”\t”);
}
System.out.println();
System.out.println(“**********************************”);
// Array
Arrays.sort(str);
System.out.println(“…”);
for (int i = 0; i < str.length; i++) {
System.out.print(str[i]+”\t”);
}
}
}
package paixu;
public class SortTest {
public static void main(String[] args) {
String[] str={“A”,”C”,”B”,”E”,”D”};
SortName sn=new SortName();
sn.sortN(str);
}
}
7.Solving class names
8.junit
Junit
> is imported into the project.—> —>Build Path—->Add Libraries—>JUnit—->junit4—-finish
> point to test..java Document—>new—>JUnit Test Case—>New JUnit 4 test—>—->next—>—>@testpublic—->Red bars represent mistakes. Blue bars represent normal.
Give an example:
public class JunitUse {
/**/
public int add(int a,int b){
int c=a+b;
return c;
}
/**/
public int minus(int a,int b){
int c=a-b;
return c;
}
}
import static org.junit.Assert.*;
import org.junit.Test;
public class JunitUseTest {
@Test
public void testAdd() {
JunitUse ju=new JunitUse();
assertEquals(14, ju.add(10, 4));
}
@Test
public void testMinus() {
JunitUse ju=new JunitUse();
assertEquals(6, ju.minus(10, 4));
}
}
10.Why do we need bags?
A folder will have the same name, more files, and more confused management.
11. package
Solving the problem of homonyms of classes
1” allows classes to form smaller units (similar to folders), making it easy to find and use the corresponding files
23
13.12Give an example:
www.wei.com
com.wei.entity com.wei. dao com.wei. util
3
procedureimport View Source
window–>preferences—->java—>Installed JRES—-> point” in the song bodyjret—> point” in the song bodyedi—>rt.jar—>Souerce Attach —>jd— > point” in the song bodysrc—->ok
public class Zhazhziji1 {
public String zhazhi(String fruit){
String juice=fruit+”“;
return juice;
}
}
package demo2;
public class test {
public static void main(String[] args) {
Zhazhziji1 zz=new Zhazhziji1();
String juice=zz.zhazhi(““);
System.out.println(juice);
}
}
1. > access modifier> <>(<>) {
// method
}
public class StudentsBiz {
String[ ] names = new String[30];
public void addName(String name) {
//}
public void showNames() { // shows the names of all students.}
}
2..1, parameters2,n
Give an example:
public static void main(String[] args) {
StudentsBiz st = new StudentsBiz(); First instantiate objects, then use them.
Scanner input = new Scanner(System.in);
for(int i=0;i<5;i++){
System.out.print(““);
String newName = input.next;
st.addName(newName);
st.addName(newName);
}
st.showNames();
}
3.Give an example:
package demo3;
public class StudentBiz {
public String[] students=new String[6]; //public void add(String name){
for (int i = 0; i < students.length; i++) {
if (students[i]==null) { students[i]=name;
break;
}
}
}
//public void show(){
for (int i = 0; i < students.length; i++) {
System.out.println(students[i]+”\t”);
}
}
//public boolean find(int begin,int end,String name){
boolean rs=false;
for (int i = begin; i < end; i++) {
if (students[i].equals(name)) {
rs=true;
break;
}
}
return rs;
}
}
package demo3;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
StudentBiz sbz=new StudentBiz();
//for (int i = 0; i < sbz.students.length; i++) {
System.out.println(“ >“+(i+1)+”“);
String name=input.next();
sbz.add(name);
}
// shows all student information.
for (int i = 0; i < sbz.students.length; i++) {
System.out.println(sbz.students[i]);
}
//System.out.println(““);
String findName=input.next();
boolean rs=sbz.find(1, 4, findName);
if (rs) {
System.out.println(“success”);
}else{
System.out.println(“fail”);
}
}
}
4. > taking ginseng
1.//public void addName(String name){
//}
//“) >;
2. //public boolean searchName(int start ,int end ,String name){
//}
//String s=”“;
int e=3;
String name=”“;
boolean flag=. searchName(s ,e ,name)
Method calls are formal arguments without actual values.
When it is called, it is the actual parameter.
3.//public boolean searchName(int start,int end,String name){
//}
//int s=1;
int e=3;
boolean flag= .searchName(s,e);
4.//public boolean searchName(int start,int end,String name){
//}
//int s=1;
int e=3;
String name=”“;
package zuoye;
public class editName {
public String[] customer=new String[5];
//public void add(String name){
for (int i = 0; i < customer.length; i++) {
if (customer[i]==null) {
customer[i]=name;
break;
}
}
}
//public boolean editName(String oldName,String newName){
boolean find=false;
for (int i = 0; i <customer.length ; i++) {
if (customer[i].equals(oldName)) {
customer[i]=newName;
find=true;
break;
}
}
return find;
}
//public void show(){
System.out.println(“*****************”);
System.out.println(““);
System.out.println(“*****************”);
for (int i = 0; i < customer.length; i++) {
System.out.print(customer[i]+”\t”);
}
System.out.println();
}
}
package zuoye;
import java.util.Scanner;
public class editNameTest {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
//editName a=new editName();
for (int i = 0; i < a.customer.length; i++) {
System.out.print(“:”);
String name=input.next();
a.add(name);
}
//a.show();
//System.out.println(““);
String oldName=input.next();
System.out.println(““);
String newName=input.next();
System.out.println(“**********”);
boolean rs=a.editName(oldName,newName);
if(rs){
System.out.println(““);
}else{
System.out.println(““);
}
/*if (a.editName(oldName,newName)) {
System.out.println(““);
}else{
System.out.println(““);
}
*/
a.show();
}
}
5.Give an example:
public class Mark {
/**/
public double calcMax(double[] marks){ double max=0;
for (int i = 0; i < marks.length; i++) {
if (marks[i]>max) {
max=marks[i];
}
}
return max;
}
/**/
public double calcAvg(double[] marks){
double sum=0;
double avg=0;
for (int i = 0; i < marks.length; i++) {
sum=sum+marks[i];
}
avg=sum/marks.length;
return avg;
}
}
public class MarksTest {
public static void main(String[] args) {
double[] marks={10,20,30,40,50,60,70,80,90,100};
Mark m=new Mark();
double max=m.calcMax(marks);
double avg=m.calcAvg(marks);
System.out.println(“max”+max);
System.out.println(“avg”+avg);
}
}
Mind:
6. objects in Song body as parameters
Multiple related information can be encapsulated into objects and passed as parameters to avoid too many parameters.
package ;
public class Student {
/*public String name;
public int age;
public double mark;
public String id;
/**/
public void info(){
System.out.println(““+name+”“+age+”“+mark+”“+id);
}
}
package ;
/**/
public class StudentBiz2 {
/**/
public Student[] students=new Student[5];
/* */
public void save(Student stu){
for (int i = 0; i < students.length; i++) {
if (students[i]==null) {
students[i]=stu;
break;
}
}
}
/*
* id
* * */
public Student find(String id) {
Student s=null;//“
for (int i = 0; i < students.length; i++) {
if(students[i].id.equals(id)) {
s=students[i];
break;
}
}
return s;
}
/* shows all student information.*/
public void show(){
System.out.println(“************************”);
System.out.println(“\t\t\t“);
for (int i = 0; i < students.length; i++) {
System.out.println(students[i].id+”\t\t”+students[i].name+”\t\t”+students[i].mark+”\t\t”+students[i].age);
}
System.out.println(“************************”);
}
/* */
public boolean editStudent(Student s){
boolean find=false;
for (int i = 0; i <students.length ; i++) {
if (students[i].id.equals(s.id)) {
students[i].name=s.name;
students[i].age=s.age;
students[i].mark=s.mark;
find=true;
break;
}
}
return find;
}
}
package ;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
StudentBiz2 sbz=new StudentBiz2();
//for (int i = 0; i < sbz.students.length; i++) {
Student s=new Student();
System.out.println(“ >“+(i+1)+”“);
System.out.println(““);
s.id=input.next();
System.out.println(““);
s.name=input.next();
System.out.println(““);
s.age=input.nextInt();
System.out.println(““);
s.mark=input.nextDouble();
sbz.save(s);
}
// shows all student information.
sbz.show();
//id System.out.println(“id”);
String id=input.next();
Student stu=sbz.find(id);
stu.info();
//Student sEdit=new Student();
System.out.println(““);
sEdit.id=input.next();
System.out.println(““);
sEdit.name=input.next();
System.out.println(““);
sEdit.age=input.nextInt();
System.out.println(““);
sEdit.mark=input.nextDouble();
boolean rs=sbz.editStudent(sEdit);
if(rs){
System.out.println(“success”);
}else{
System.out.println(“fail !“);
}
// sbz.show();
}
}
Exercise: sorting customer names
package paixu;
import java.util.Arrays;
public class SortName {
public void sortN(String[] str){
System.out.println(“…”);
for (int i = 0; i < str.length; i++) {
System.out.print(str[i]+”\t”);
}
System.out.println();
System.out.println(“**********************************”);
// Array
Arrays.sort(str);
System.out.println(“…”);
for (int i = 0; i < str.length; i++) {
System.out.print(str[i]+”\t”);
}
}
}
package paixu;
public class SortTest {
public static void main(String[] args) {
String[] str={“A”,”C”,”B”,”E”,”D”};
SortName sn=new SortName();
sn.sortN(str);
}
}
7.Solving class names
8.junit
Junit
> is imported into the project.—> —>Build Path—->Add Libraries—>JUnit—->junit4—-finish
> point to test..java Document—>new—>JUnit Test Case—>New JUnit 4 test—>—->next—>—>@testpublic—->Red bars represent mistakes. Blue bars represent normal.
Give an example:
public class JunitUse {
/**/
public int add(int a,int b){
int c=a+b;
return c;
}
/**/
public int minus(int a,int b){
int c=a-b;
return c;
}
}
import static org.junit.Assert.*;
import org.junit.Test;
public class JunitUseTest {
@Test
public void testAdd() {
JunitUse ju=new JunitUse();
assertEquals(14, ju.add(10, 4));
}
@Test
public void testMinus() {
JunitUse ju=new JunitUse();
assertEquals(6, ju.minus(10, 4));
}
}
10.Why do we need bags?
A folder will have the same name, more files, and more confused management.
11. package
Solving the problem of homonyms of classes
1” allows classes to form smaller units (similar to folders), making it easy to find and use the corresponding files
23
13.12Give an example:
www.wei.com
com.wei.entity com.wei. dao com.wei. util
3
procedureimport View Source
public class Mark {
/**/
public double calcMax(double[] marks){ double max=0;
for (int i = 0; i < marks.length; i++) {
if (marks[i]>max) {
max=marks[i];
}
}
return max;
}
/**/
public double calcAvg(double[] marks){
double sum=0;
double avg=0;
for (int i = 0; i < marks.length; i++) {
sum=sum+marks[i];
}
avg=sum/marks.length;
return avg;
}
}
public class MarksTest {
public static void main(String[] args) {
double[] marks={10,20,30,40,50,60,70,80,90,100};
Mark m=new Mark();
double max=m.calcMax(marks);
double avg=m.calcAvg(marks);
System.out.println(“max”+max);
System.out.println(“avg”+avg);
}
}
Mind:
6. objects in Song body as parameters
Multiple related information can be encapsulated into objects and passed as parameters to avoid too many parameters.
package ;
public class Student {
/*public String name;
public int age;
public double mark;
public String id;
/**/
public void info(){
System.out.println(““+name+”“+age+”“+mark+”“+id);
}
}
package ;
/**/
public class StudentBiz2 {
/**/
public Student[] students=new Student[5];
/* */
public void save(Student stu){
for (int i = 0; i < students.length; i++) {
if (students[i]==null) {
students[i]=stu;
break;
}
}
}
/*
* id
* * */
public Student find(String id) {
Student s=null;//“
for (int i = 0; i < students.length; i++) {
if(students[i].id.equals(id)) {
s=students[i];
break;
}
}
return s;
}
/* shows all student information.*/
public void show(){
System.out.println(“************************”);
System.out.println(“\t\t\t“);
for (int i = 0; i < students.length; i++) {
System.out.println(students[i].id+”\t\t”+students[i].name+”\t\t”+students[i].mark+”\t\t”+students[i].age);
}
System.out.println(“************************”);
}
/* */
public boolean editStudent(Student s){
boolean find=false;
for (int i = 0; i <students.length ; i++) {
if (students[i].id.equals(s.id)) {
students[i].name=s.name;
students[i].age=s.age;
students[i].mark=s.mark;
find=true;
break;
}
}
return find;
}
}
package ;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
StudentBiz2 sbz=new StudentBiz2();
//for (int i = 0; i < sbz.students.length; i++) {
Student s=new Student();
System.out.println(“ >“+(i+1)+”“);
System.out.println(““);
s.id=input.next();
System.out.println(““);
s.name=input.next();
System.out.println(““);
s.age=input.nextInt();
System.out.println(““);
s.mark=input.nextDouble();
sbz.save(s);
}
// shows all student information.
sbz.show();
//id System.out.println(“id”);
String id=input.next();
Student stu=sbz.find(id);
stu.info();
//Student sEdit=new Student();
System.out.println(““);
sEdit.id=input.next();
System.out.println(““);
sEdit.name=input.next();
System.out.println(““);
sEdit.age=input.nextInt();
System.out.println(““);
sEdit.mark=input.nextDouble();
boolean rs=sbz.editStudent(sEdit);
if(rs){
System.out.println(“success”);
}else{
System.out.println(“fail !“);
}
// sbz.show();
}
}
Exercise: sorting customer names
package paixu;
import java.util.Arrays;
public class SortName {
public void sortN(String[] str){
System.out.println(“…”);
for (int i = 0; i < str.length; i++) {
System.out.print(str[i]+”\t”);
}
System.out.println();
System.out.println(“**********************************”);
// Array
Arrays.sort(str);
System.out.println(“…”);
for (int i = 0; i < str.length; i++) {
System.out.print(str[i]+”\t”);
}
}
}
package paixu;
public class SortTest {
public static void main(String[] args) {
String[] str={“A”,”C”,”B”,”E”,”D”};
SortName sn=new SortName();
sn.sortN(str);
}
}
7.Solving class names
8.junit
Junit
> is imported into the project.—> —>Build Path—->Add Libraries—>JUnit—->junit4—-finish
> point to test..java Document—>new—>JUnit Test Case—>New JUnit 4 test—>—->next—>—>@testpublic—->Red bars represent mistakes. Blue bars represent normal.
Give an example:
public class JunitUse {
/**/
public int add(int a,int b){
int c=a+b;
return c;
}
/**/
public int minus(int a,int b){
int c=a-b;
return c;
}
}
import static org.junit.Assert.*;
import org.junit.Test;
public class JunitUseTest {
@Test
public void testAdd() {
JunitUse ju=new JunitUse();
assertEquals(14, ju.add(10, 4));
}
@Test
public void testMinus() {
JunitUse ju=new JunitUse();
assertEquals(6, ju.minus(10, 4));
}
}
10.Why do we need bags?
A folder will have the same name, more files, and more confused management.
11. package
Solving the problem of homonyms of classes
1” allows classes to form smaller units (similar to folders), making it easy to find and use the corresponding files
23
www.wei.com
com.wei.entity com.wei. dao com.wei. util
3
window–>preferences—->java—>Installed JRES—-> point” in the song bodyjret—> point” in the song bodyedi—>rt.jar—>Souerce Attach —>jd— > point” in the song bodysrc—->ok
