PPT 对应代码示例
常见大段代码
示例一
import java.util.ArrayList;
import java.util.List;
/**
* @author tanglonglong ＼(－－)／
* @version 1.0
* @date 2020/3/9 13:58
*/
public class Person {
private String givenName;
private String surName;
private int age;
private String sex;
private String eMail;
private String phone;
private String address;
public static class Builder{
private String givenName="";
private String surName="";
private int age = 0;
private String sex;
private String eMail = "";
private String phone = "";
private String address = "";
public Person.Builder givenName(String givenName){
this.givenName = givenName;
return this;
}
public Person.Builder surName(String surName){
this.surName = surName;
return this;
}
public Person.Builder age (int val){
age = val;
return this;
}
public Person.Builder sex(String val){
sex = val;
return this;
}
public Person.Builder email(String val){
eMail = val;
return this;
}
public Person.Builder phoneNumber(String val){
phone = val;
return this;
}
public Person.Builder address(String val){
address = val;
return this;
}
public Person build(){
return new Person(this);
}
}
private Person(){
super();
}
private Person(Person.Builder builder){
givenName = builder.givenName;
surName = builder.surName;
age = builder.age;
sex = builder.sex;
eMail = builder.eMail;
phone = builder.phone;
address = builder.address;
}
public String getGivenName(){
return givenName;
}
public String getSurName(){
return surName;
}
public int getAge(){
return age;
}
public String getSex(){
return sex;
}
public void print(){
System.out.println(
"\nName: " + givenName + " " + surName + "\n" +
"Age: " + age + "\n" +
"String: " + sex + "\n" +
"eMail: " + eMail + "\n" +
"Phone: " + phone + "\n" +
"Address: " + address + "\n"
);
}
public void printName(){
System.out.println(
"Name: " + givenName + " " + surName);
}
@Override
public String toString(){
return "Name: " + givenName + " " + surName + "\n" + "Age: " + age + " String: " + sex + "\n" + "eMail: " + eMail + "\n" + "Address: " + address + "\n";
}
public static List<Person> createShortList(){
List<Person> people = new ArrayList<>();
people.add(
new Person.Builder()
.givenName("Bob")
.surName("Baker")
.age(21)
.sex("女")
.email("bob.baker@example.com")
.phoneNumber("201-121-4678")
.address("44 4th St, Smallville, KS 12333")
.build()
);
people.add(
new Person.Builder()
.givenName("Jane")
.surName("Doe")
.age(25)
.sex("男")
.email("jane.doe@example.com")
.phoneNumber("202-123-4678")
.address("33 3rd St, Smallville, KS 12333")
.build()
);
people.add(
new Person.Builder()
.givenName("John")
.surName("Doe")
.age(25)
.sex("女")
.email("john.doe@example.com")
.phoneNumber("202-123-4678")
.address("33 3rd St, Smallville, KS 12333")
.build()
);
people.add(
new Person.Builder()
.givenName("James")
.surName("Johnson")
.age(45)
.sex("女")
.email("james.johnson@example.com")
.phoneNumber("333-456-1233")
.address("201 2nd St, New York, NY 12111")
.build()
);
people.add(
new Person.Builder()
.givenName("Joe")
.surName("Bailey")
.age(17)
.sex("女")
.email("joebob.bailey@example.com")
.phoneNumber("112-111-1111")
.address("111 1st St, Town, CA 11111")
.build()
);
people.add(
new Person.Builder()
.givenName("Phil")
.surName("Smith")
.age(11)
.sex("女")
.email("phil.smith@examp;e.com")
.phoneNumber("222-33-1234")
.address("22 2nd St, New Park, CO 222333")
.build()
);
people.add(
new Person.Builder()
.givenName("Betty")
.surName("Jones")
.age(85)
.sex("男")
.email("betty.jones@example.com")
.phoneNumber("211-33-1234")
.address("22 4th St, New Park, CO 222333")
.build()
);
return people;
}
}
改造前
/*对属性进行筛选后，进行打印*/
public class FilterPrint {
/*筛成年男性为第一组，进行打印*/
public void method1(List<Person> pl){
for(Person p:pl){
if (isManAndAdult(p)){
printManAndAdult(p);
}
}
}
/*筛未成年女性为第二组，进行打印*/
public void method2(List<Person> pl){
for(Person p:pl){
if (isWomenAndChild(p)){
printWomenAndChild(p);
}
}
}
public boolean isManAndAdult(Person p){
return p.getAge() >= 18 && p.getSex() == "男";
}
public boolean isWomenAndChild(Person p){
return p.getAge() < 18 && p.getSex() == "女";
}
public void printManAndAdult(Person p){
System.out.println("Group1 " + p.getGivenName() + " " + p.getSurName() + " age " + p.getAge());
}
public void printWomenAndChild(Person p){
System.out.println("Group2 " + p.getGivenName() + " " + p.getSurName() + " age " + p.getAge());
}
}
/*调用并打印*/
public class Main {
public static void main(String[] args) {
FilterPrint filterPrint = new FilterPrint();
filterPrint.method1(Person.createShortList());
filterPrint.method2(Person.createShortList());
}
}
改造后
//--> 这里发生了变化 使用JAVA提供的Predicate接口<--
public interface Predicate<T> {
public boolean test(T t);
}
/*对属性进行筛选后，进行打印*/
public class FilterPrint {
/*筛成年男性为第一组，进行打印*/
//--> 这里发生了变化 传入 Predicate 的实现 <--
public void method1((List<Person> pl, Predicate<Person> pred){
for(Person p:pl){
if (pred.test(p)){
printManAndAdult(p);
}
}
}
/*筛未成年女性为第二组，进行打印*/
//--> 这里发生了变化 传入 Predicate 的实现 <--
public void method2(List<Person> pl, Predicate<Person> pred){
for(Person p:pl){
if (pred.test(p)){
printWomenAndChild(p);
}
}
}
public void printManAndAdult(Person p){
System.out.println("Group1 " + p.getGivenName() + " " + p.getSurName() + " age " + p.getAge());
}
public void printWomenAndChild(Person p){
System.out.println("Group2 " + p.getGivenName() + " " + p.getSurName() + " age " + p.getAge());
}
}
/*调用并打印*/
public class Main{
public static void main(String[] args){
FilterPrint robo = new FilterPrint();
//--> 这里发生了变化 传入 Predicate 的实现 <--
// Predicates
robo.method1(Person.createShortList(), p->p.getAge() >= 18 && p.getSex() == "男");
robo.method2(Person.createShortList(), p->p.getAge() < 18 && p.getSex() == "女" );
}
}
示例二
改造前
/*示例二：大数据 List 集合，需要对 List 集合中的数据同标准库中数据进行对比，
生成新增，更新，取消数据*/
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
/**
* @author tanglonglong ＼(－－)／
* @version 1.0
* @date 2020/3/9 13:53
*/
public class DealList1 {
public static void main(String[] args) throws Exception {
// 开始时间
long start = System.currentTimeMillis();
List<String> list = new ArrayList<String>();
for (int i = 1; i <= 30000; i++) {
list.add(i + "");
}
// 每500条数据开启一条线程
int threadSize = 500;
// 总数据条数
int dataSize = list.size();
// 线程数
int threadNum = dataSize / threadSize + 1;
// 定义标记,过滤threadNum为整数
boolean special = dataSize % threadSize == 0;
// 创建一个线程池
ExecutorService exec = Executors.newFixedThreadPool(threadNum);
// 定义一个任务集合
List<Callable<Integer>> tasks = new ArrayList<Callable<Integer>>();
Callable<Integer> task = null;
List<String> cutList = null;
// 确定每条线程的数据
for (int i = 0; i < threadNum; i++) {
if (i == threadNum - 1) {
if (special) {
break;
}
cutList = list.subList(threadSize * i, dataSize);
} else {
cutList = list.subList(threadSize * i, threadSize * (i + 1));
}
final List<String> listStr = cutList;
task = new Callable<Integer>() {
@Override
public Integer call() throws Exception {
System.out.println(Thread.currentThread().getName() + "线程：" + listStr);
//...进行数据库对比等业务代码
return 1;
}
};
// 这里提交的任务容器列表和返回的Future列表存在顺序对应的关系
tasks.add(task);
}
List<Future<Integer>> results = exec.invokeAll(tasks);
for (Future<Integer> future : results) {
System.out.println(future.get());
}
// 关闭线程池
exec.shutdown();
System.out.println("线程任务执行结束");
System.err.println("执行任务消耗了 ：" + (System.currentTimeMillis() - start) + "毫秒");
}
}
改造后
import java.util.ArrayList;
import java.util.List;
/**
* @author tanglonglong ＼(－－)／
* @version 1.0
* @date 2020/3/9 15:45
*/
public class DealList2 {
public static void main(String[] args) throws Exception {
// 开始时间
long start = System.currentTimeMillis();
List<String> list = new ArrayList<String>();
for (int i = 1; i <= 3000; i++) {
list.add(i + "");
}
list.parallelStream().forEach((p)->{
//...进行数据库对比等业务代码
});
System.err.println("执行任务消耗了 ：" + (System.currentTimeMillis() - start) + "毫秒");
}
}
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