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javaDeveloperBookjavaDeveloperBook
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javastudy第一次提交
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‎src/com/java/demo01/Demo.java

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package com.java.demo01;
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import java.util.Date;
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public class Demo {
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public static void main(String[] args) {
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Employee employee = new Employee() ;
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employee.setEmpId(10000);
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employee.setEmpName("jack w");
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employee.setEmpDate(new Date());
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System.out.println(employee);
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}
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}

‎src/com/java/demo01/Employee.java

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package com.java.demo01;
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import java.util.Date;
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/**
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* 代码模型01 : 简单Java类 <br/>
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* 1.类名应该有意义，Dog、Cat....
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* 2.类中的属性必须用private封装，所以需要有 getter 、 setter方法
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* 3.类中可以定义若干个构造方法，但是必须要有一个无参构造
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* 4.类中不能出现 System.out.println()语句，所有的输出必须在调用处执行
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* 5.类中应该有返回类完整信息的方法： toString()
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*
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* @author jack w
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*
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*/
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public class Employee {
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private Integer empId;
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private String empName;
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private Date empDate;
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public Employee() {
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}
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public Integer getEmpId() {
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return empId;
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}
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public void setEmpId(Integer empId) {
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this.empId = empId;
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}
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public String getEmpName() {
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return empName;
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}
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public void setEmpName(String empName) {
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this.empName = empName;
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}
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public Date getEmpDate() {
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return empDate;
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}
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public void setEmpDate(Date empDate) {
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this.empDate = empDate;
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}
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@Override
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public int hashCode() {
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final int prime = 31;
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int result = 1;
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result = prime * result + ((empDate == null) ? 0 : empDate.hashCode());
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result = prime * result + ((empId == null) ? 0 : empId.hashCode());
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result = prime * result + ((empName == null) ? 0 : empName.hashCode());
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return result;
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}
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@Override
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public boolean equals(Object obj) {
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if (this == obj)
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return true;
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if (obj == null)
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return false;
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if (getClass() != obj.getClass())
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return false;
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Employee other = (Employee) obj;
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if (empDate == null) {
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if (other.empDate != null)
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return false;
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} else if (!empDate.equals(other.empDate))
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return false;
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if (empId == null) {
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if (other.empId != null)
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return false;
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} else if (!empId.equals(other.empId))
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return false;
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if (empName == null) {
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if (other.empName != null)
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return false;
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} else if (!empName.equals(other.empName))
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return false;
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return true;
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}
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@Override
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public String toString() {
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return "Employee [empId=" + empId + ", empName=" + empName + ", empDate=" + empDate + "]";
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}
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}

‎src/com/java/demo02/Demo.java

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package com.java.demo02;
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/**
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* 测试对象比较
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*
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* @author jack w
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*
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*/
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public class Demo {
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public static void main(String[] args) {
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Person personA = new Person("jack w", 10) ;
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Person personB = new Person("jack w",10) ;
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System.out.println(personA.equals(personB));
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}
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}

‎src/com/java/demo02/Person.java

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package com.java.demo02;
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/**
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* 代码模型02 : 对象比较
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*
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* @author jack w
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*
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*/
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public class Person {
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private String name;
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private Integer age;
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public Person() {
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}
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public Person(String name, Integer age) {
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super();
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this.name = name;
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this.age = age;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public Integer getAge() {
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return age;
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}
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public void setAge(Integer age) {
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this.age = age;
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}
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/**
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* 判断两个对象是否相等
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*/
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@Override
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public boolean equals(Object obj) {
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if (this == obj) {
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return true;
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}
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if (obj == null) {
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return false;
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}
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if (this.getClass() != obj.getClass()) {
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return false;
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}
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Person other = (Person) obj;
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if (this.name == null) {
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if (other.name != null) {
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return false;
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}
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} else {
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if (!this.name.equals(other.name)) {
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return false;
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}
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}
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if (this.age == null) {
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if (other.age != null) {
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return false;
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}
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} else {
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if (!this.age.equals(other.age)) {
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return false;
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}
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}
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return true;
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}
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@Override
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public String toString() {
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return "Person [name=" + name + ", age=" + age + "]";
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}
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}

‎src/com/java/demo03/OneToMany.java

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package com.java.demo03;
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/**
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* 数据表与简单java类 ： 一对多
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* 还有多对多，类似的，就没有写了
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*
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*
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* @author jack w
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*
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*/
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class Employee {
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private Integer empId;
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private String name;
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private Double salary;
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private Department department;
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private Employee manager;
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public Employee() {
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}
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public Employee(Integer empId, String name, Double salary) {
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this.empId = empId;
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this.name = name;
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this.salary = salary;
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}
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public void setDepartment(Department department) {
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this.department = department;
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}
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public Department getDepartment() {
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return department;
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}
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public void setManager(Employee manager) {
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this.manager = manager;
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}
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public Employee getManager() {
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return manager;
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}
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@Override
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public String toString() {
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return "Employee [empId=" + empId + ", name=" + name + ", salary=" + salary + ", department=" + department
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+ ", manager=" + manager + "]";
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}
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}
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class Department {
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private Integer deptId;
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private String deptName;
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private Employee[] employees;
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public Department() {
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}
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public Department(Integer deptId, String deptName) {
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this.deptId = deptId;
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this.deptName = deptName;
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}
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public void setEmployees(Employee[] employees) {
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this.employees = employees;
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}
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public Employee[] getEmployees() {
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return employees;
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}
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}
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public class OneToMany {
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public static void main(String[] args) {
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Employee emp1 = new Employee(1001, "jack", 1000.00);
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Employee emp2 = new Employee(1002, "smith", 2000.00);
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Employee emp3 = new Employee(1003, "tom", 4000.00);
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Department dept1 = new Department(1, "技术部");
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Department dept2 = new Department(2, "产品部");
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emp1.setDepartment(dept1);
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emp1.setManager(emp3);
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emp2.setDepartment(dept2);
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emp2.setManager(emp3);
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emp3.setDepartment(dept2);
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dept1.setEmployees(new Employee[]{emp1});
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dept2.setEmployees(new Employee[]{emp2,emp3});
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for (int i = 0; i < dept1.getEmployees().length; i++) {
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System.out.println(dept1.getEmployees()[i].toString());
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}
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}
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}

‎src/com/java/demo04/TryCatchFinally.java

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package com.java.demo04;
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/**
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* 代码模型05 ： 异常处理模型
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*
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* @author jack w
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*
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*/
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class MyMath {
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public static double div(Integer x , Integer y) throws Exception{
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double result = 0;
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try {
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System.out.println("【开始】除法计算开始");
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result = x / y;
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} catch (Exception e) {
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throw e ;
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}finally {
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System.out.println("【结束】除法计算结束");
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}
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return result;
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}
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}
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public class TryCatchFinally {
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public static void main(String[] args) {
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try {
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System.out.println(MyMath.div(10, 0));
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}

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