Java学习笔记------static

static

创建Javabean类

public class student {private int age;private String name;private String gender;public student() {}public student(int age, String name, String gender) {this.age = age;this.name = name;this.gender = gender;}/*** 获取* @return age*/public int getAge() {return age;}/*** 设置* @param age*/public void setAge(int age) {this.age = age;}/*** 获取* @return name*/public String getName() {return name;}/*** 设置* @param name*/public void setName(String name) {this.name = name;}/*** 获取* @return gender*/public String getGender() {return gender;}/*** 设置* @param gender*/public void setGender(String gender) {this.gender = gender;}public void show(){System.out.println(name+","+age+","+gender);}public void study(){System.out.println(name+"正在学习。");}
}

运行

public class test {public static void main(String[] args) {student s1=new student();s1.setName("张三");s1.setAge(23);s1.setGender("男");s1.study();s1.show();student s2=new student();s2.setName("李四");s2.setAge(24);s2.setGender("女");s2.study();s2.show();}
}

加入老师名字

public class student {private int age;private String name;private String gender;public static String teachername;public student() {}public student(int age, String name, String gender) {this.age = age;this.name = name;this.gender = gender;}public student(int age, String name, String gender, String teachername) {this.age = age;this.name = name;this.gender = gender;this.teachername = teachername;}/*** 获取* @return age*/public int getAge() {return age;}/*** 设置* @param age*/public void setAge(int age) {this.age = age;}/*** 获取* @return name*/public String getName() {return name;}/*** 设置* @param name*/public void setName(String name) {this.name = name;}/*** 获取* @return gender*/public String getGender() {return gender;}/*** 设置* @param gender*/public void setGender(String gender) {this.gender = gender;}public void show(){System.out.println(name+","+age+","+gender+","+teachername);}public void study(){System.out.println(name+"正在学习。");}}

每次赋值老师名字太麻烦，在定义类中老师多加入static

即为public static String teachername；类中所有对象共享同一个老师

用student.teachername=''李白''；即可

static表示静态，是Java中的一个修饰符，可以修饰成员方法，成员变量，分别叫静态变量、静态方法。

静态变量：被该类所有对象共享、不属于对象，属于类，随类的加载而加载，优先对象存在

调用方式分为类名调用（student.teachername=''李白''；）、对象名调用（s1.teachername=''李白''；）。

静态方法：多用在测试类和工具类中，Javabean很少会用

调用方式：类名调用、对象名调用

工具类：帮助我们做一些事情的，但是不描述任何事物的类

类名见名知意，私有化构造方法，方法定义为静态

例如：