本文目录
- Java如何创建一个类
- java 定义类 如何写
- 怎么用“java“写一个类
- 在java中,如何声明一个类
- JAVA编写一个类
- 怎么用java写一个类
- java编程一个类
- java中怎样创建一个类有那些方法,请举例说明.谢谢!
- java如何定义一个类,创建它的成员变量和方法
Java如何创建一个类
定义一个类,class A={},然后创建这个类对象,A a = new A();有没有参数看你类定义的构造函数; 例代码如下:class TestInner{public static void main(String args){Outer outer = new Outer();Outer.Inner inner = outer.new Inner();}}在内部类(Inner Class),可以随意的访问外部类的成员,这可让我们更好地组织管理我们的代码,增强代码的可读性。
java 定义类 如何写
类是一种引用数据类型。类为对象的模板,简单的说就是分类。类的定义包括“成员变量”的定义和“方法”的定义,其中“成员变量”用于描述一类对象共同的数据结构。在Java语言中,类的成员变量的定义可以使用如下语法:class 类名 {成员变量类型变量名称;………}类是用class关键字来定义的一种抽象数据类型,类不但定义了抽象数据类型的组成(成员变量),同时还定义了对该类型可以实施的操作(方法),类名的首字母必须大写。看如下代码定义了雇员类:/** 定义雇员类 */public class Emp{String name;int age;char gender;double salary;}在如上的实例代码中,仅仅定义了Emp类型的组成,即成员变量。该类定义了4个成员变量:String类型的name用于存放名字;int类型的age用于存放年龄;char类型的gender用于存放性别;double类型的salary用于存放工资。
怎么用“java“写一个类
class B{\x0d\x0a private int a;//声明变量\x0d\x0a public B()//构造函数\x0d\x0a{\x0d\x0a}\x0d\x0apublic void setA(int a)//设置a的值\x0d\x0a{\x0d\x0a this.a=a;\x0d\x0a\x0d\x0a}\x0d\x0apublic int getA()//获取a的值\x0d\x0a{\x0d\x0areturn a;\x0d\x0a}\x0d\x0apublic public static void main(String args)//必须要的主函数\x0d\x0a{\x0d\x0aB b=new B();//建立一个B的对象b\x0d\x0ab.setA(3);//调用b对象里的方法setA();\x0d\x0aSystem.out.println(b.getA);//输出a\x0d\x0a\x0d\x0a}\x0d\x0a\x0d\x0a}
在java中,如何声明一个类
声明一个类需要借助java关键字class,如声明一个ClassName类
public class ClassName{ //...}
其中public是类修饰符,表示公共类,还有一些修饰符说明如下
public 公共类default 默认类(即class前什么都不加)abstract 抽象类 fanal 不能被继承的类 static 静态类
private 只能修饰内部类,一般不推荐使用
类名命名规范
类名是一个名词,应该大小写混合的方式,每一个单词的首字母大写。
类的名字必须是大写字母开头,而单词中的其他字母的均小写 例如:Test
如果类名由多个单词组成,则每个单词的首字母均应该大写 例如:TestPage
如果类名称中包含单词缩写,则缩写词的每一个字母均大写 例如:XMLExample
JAVA编写一个类
用set和get方法,属性封装。private String str;public void setStr(String str) { this.str = str;}public String getStr() { return str;}用eclipse工具,在类中直接创建一个变量如下:private String str;然后在类中点击右键,选择Source(快捷键为Shift+Alt+s)----》Generate Getters and Setters,然后选择你需要添加方法的变量就可以自动生成set和get方法了。如果有特殊的业务逻辑,可以在set和get方法中写入算法。
怎么用java写一个类
一个java标准类的必备要素如下:
//定义类的归属,即包名
package com.test;//定义类名,public关键字为可选,不过如果为public,则源文件必须与类名一致.public class Test{ //定义类属性 private int id; //构造方法 public Test(int id){ this.id = id; } //get,set方法 public void setId(int id){ this.id = id; } public int getId(){ return this.id; } //自定义方法 public void doMethod(){ //TODO 方法的返回值和参数,依据业务逻辑 }}//以上为一个最简化的java类.可以增加静态方法,比如程序入口
java编程一个类
代码如下,根据以前写的一段代码修改得到的:
import java.math.BigDecimal;import java.util.ArrayList;import java.util.Date;import java.util.List;import java.util.Scanner; public class Bank { private List《Customer》 customerList = new ArrayList《Customer》();//bank customer list private Long accountNoSequance = 10001L;//use to generate customerAccount /** * @return the customerList */public List《Customer》 getCustomerList() {return customerList;}/** * @param customerList the customerList to set */public void setCustomerList(List《Customer》 customerList) {this.customerList = customerList;}public void addCustomer(Customer customer) {customer.setAccountNo(this.accountNoSequance.toString());this.getCustomerList().add(customer);this.accountNoSequance++;System.out.println("--- add customer sucess ---");customer.showDetail();}public Customer getCustomerByAccountNo(String accountNo) {if(accountNo == null || accountNo.trim().equals("")){return null;}Customer result = null;if(this.getCustomerList().size()》0) {for(Customer tmp : this.getCustomerList()) {if(accountNo.equals(tmp.getAccountNo())) {result = tmp;break;}}}return result;}/** * * Title: Class Bank.java * Description: internal class for define customer object * */public class Customer{ private String name; private String address; private String phoneNo; private String accountNo; private BigDecimal balance = new BigDecimal(0L);// init balance private List《Transaction》 txnList = new ArrayList《Transaction》();// Transaction detail public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public String getPhoneNo() { return phoneNo; } public void setPhoneNo(String phoneNo) { this.phoneNo = phoneNo; } public String getAccountNo() { return accountNo; } public void setAccountNo(String accountNo) { this.accountNo = accountNo; } /** * @return the balance */public BigDecimal getBalance() {return balance;}/** * @param balance the balance to set */public void setBalance(BigDecimal balance) {this.balance = balance;}public List《Transaction》 getTxnList() { return txnList; } public void setTxnList(List《Transaction》 txnList) { this.txnList = txnList; } @Override public String toString() { return "Customer "; } } private void showMenu(Scanner reader){ System.out.println("--- Choose menu ---"); System.out.println("please input number 1-6 to choose menu; 1: add new customer, 2:deposit money, 3:withdraw money, 4: transfer money, 5:view details or 6:exit"); if(reader.hasNextInt()){ int flag = reader.nextInt(); switch(flag){ case 1 :{ System.out.println(" please customer name:"); String customerName = ""; if(reader.hasNext()){ customerName = reader.next(); } if(null != customerName && !customerName.equals("")) { Customer customer = new Customer(); customer.setName(customerName); this.addCustomer(customer); showMenu(reader); } break; } case 2 :{ System.out.println(" please input account No:"); if(reader.hasNext()){ String accountNo = reader.next(); Customer customer = this.getCustomerByAccountNo(accountNo); if(null == customer) { System.out.println("this account No is not exist, please try again"); showMenu(reader); break; } System.out.println(" please input amount:"); if(reader.hasNextDouble()){ double amount = reader.nextDouble(); customer.depositing(amount); showMenu(reader); } } break; } case 3 :{ System.out.println(" please input account No:"); if(reader.hasNext()){ String accountNo = reader.next(); Customer customer = this.getCustomerByAccountNo(accountNo); if(null == customer) { System.out.println("this account No is not exist, please try again"); showMenu(reader); break; } System.out.println(" please input amount:"); if(reader.hasNextDouble()){ double amount = reader.nextDouble(); customer.withdrawing(amount); showMenu(reader); } } break; } case 4 :{ System.out.println(" please input from account No:"); if(reader.hasNext()){ String accountNoFrom = reader.next(); Customer customerFrom = this.getCustomerByAccountNo(accountNoFrom); if(null == customerFrom) { System.out.println("this account No is not exist, please try again"); showMenu(reader); break; } System.out.println(" please input to account No:"); if(reader.hasNext()){ String accountNoTo = reader.next(); Customer customerTo = this.getCustomerByAccountNo(accountNoTo); if(null == customerTo) { System.out.println("this account No is not exist, please try again"); showMenu(reader); break; } System.out.println(" please input transfer amount:"); if(reader.hasNextDouble()){ double amount = reader.nextDouble(); boolean withdrawingFlag = customerFrom.withdrawing(amount); if(withdrawingFlag) { customerTo.depositing(amount); System.out.println(" transfer success"); }else { System.out.println(" transfer failure"); } showMenu(reader); } } } break; } case 5 :{ System.out.println(" please input account No:"); if(reader.hasNext()){ String accountNo = reader.next(); Customer customer = this.getCustomerByAccountNo(accountNo); if(null == customer) { System.out.println("this account No is not exist, please try again"); showMenu(reader); break; } customer.showDetail(); showMenu(reader); } break; } case 6 :{ break; } default :{ System.out.println("invalid input "); showMenu(reader); } } } System.out.println("Do you really want to exit? yes or no "); reader.nextLine(); String outChoose = reader.nextLine(); if(!"YES".equals(outChoose.toUpperCase())&&!"Y".equals(outChoose.toUpperCase())){ showMenu(reader); } } public static void main(String args){ System.out.println("--- Welcome to Test bank ---"); Scanner reader=new Scanner(System.in); Bank bank = new Bank(); bank.showMenu(reader); }}
java中怎样创建一个类有那些方法,请举例说明.谢谢!
1、定义一个类,class A={},然后创建这个类对象,A a = new A();有没有参数看你类定义的构造函数;2、继承java已有的类,以异常类为例,class A extends Exception{}3、实现java已有接口或者抽象类,class A implements Runnable{}4、单继承多实现,class A extends B implements C,D{}
java如何定义一个类,创建它的成员变量和方法
建立一个Javaproject——点右键新建一个类,类名字最好是大写开头,LZ 我给你写一个简单的类\x0d\x0apublic class Test{\x0d\x0a//定义成员变量\x0d\x0aint width=10;\x0d\x0aint height=10;\x0d\x0a// 成员方法\x0d\x0apublic area(){\x0d\x0a return width*height ;\x0d\x0a }\x0d\x0a}