What is a static variable
Members modified by static in Java are called static members or class members. It belongs to the entire class, not to an object, that is, it is shared by all objects of the class. Static members can be accessed directly using the class name, or they can be accessed using the object name.
Use static to modify variables, methods and code blocks.
public class Test1 {
// static修飾的變量為靜態(tài)變量，所有類的對(duì)象共享hobby
static String hobby = "Tedu";
public static void main(String[] args) {
// 靜態(tài)變量可以直接使用類名來訪問，無需創(chuàng)建對(duì)象
System.out.println("通過類名訪問hobby：" + Test1.hobby);
// 創(chuàng)建類的對(duì)象
Test1 t1 = new Test1();
// 使用對(duì)象名訪問靜態(tài)變量
System.out.println("使用對(duì)象名訪hobby:" + t1.hobby);
// 使用對(duì)象名的形式修改靜態(tài)變量的值
t1.hobby = "cjj";
// 再次使用類名訪問靜態(tài)白變量，值已經(jīng)被修改
System.out.println("通過類名訪問hobby：" + Test1.hobby);
}
}Running result:
通過類名訪問hobby：Tedu 使用對(duì)象名訪hobby:Tedu 通過類名訪問hobby：cjj
Note: Static members belong to the entire class. When the system uses the class for the first time, it will allocate memory space until the Resources will be recycled only after the class is unloaded!
What is a static method
Like static variables, we can also use static modified methods, called static methods or class methods. In fact, the main method we have been writing before is a static method.
public class Test01 {
//使用static關(guān)鍵字聲明靜態(tài)方法
public static void print() {
System.out.println("歡迎你：Cjj!");
}
public static void main(String[] args) {
//直接使用類名調(diào)用靜態(tài)方法
Test01.print();
//也可以通過對(duì)象名調(diào)用，當(dāng)然更推薦使用類名調(diào)用
Test01 t1 = new Test01();
t1.print();
}
}Running result:
歡迎你：Cjj! 歡迎你：Cjj!
Note:
1. Static methods can directly call static members of the same class, but cannot directly call non-static members. static members. For example:
If you want to call non-static variables in a static method, you can create an object of the class and then access the non-static variables through the object. For example:
2. In ordinary member methods, you can directly access non-static variables and static variables of the same type, such as:
3. Non-static methods cannot be directly called in static methods. Non-static methods need to be accessed through objects. Such as:
public class Test01 {
String name = "Cjj"; //靜態(tài)成員變量
static String hobby = "study"; //非靜態(tài)成員變量
//普通成員方法
public void print1() {
System.out.println("普通成員方法~~~");
}
//靜態(tài)成員方法
public static void print2() {
System.out.println("靜態(tài)成員方法~~~");
}
public static void main(String[] args) {
//普通成員方法必須通過對(duì)象來調(diào)用
Test01 t1 = new Test01();
t1.print1();
//可以直接調(diào)用靜態(tài)方法
print2();
}
} Recommended tutorial: java introductory tutorial
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