What should you pay attention to when using variables in java

Explanation

1. Each variable has a type. The type can be a basic type or a reference type.

2. The variable name must be a legal identifier.

3. A variable declaration is a complete statement, so each declaration must end with a semicolon.

Example

public class demo04 {
    //类变量
    static double salary =2500;
    // 属性   变量
    //实例变量：从属于对象；如果不进行初始化，这个类型的默认值为0，0.0。
    //布尔值：默认值为false
    //除了基本类型，其余的默认值都是null；
    String name;
    int age;
    //main方法
    public static void main(String[] args) {
        //局部变量：必须声明和初始化值；
        int i = 10;
        System.out.println(i);
        //使用实例变量
        //变量类型  变量名字 = new Demo04();
        demo04 demo04 = new demo04();  //alt+enter
        System.out.println(demo04.age);
        System.out.println(demo04.name);
        System.out.println(salary);
    }
    
    //其他方法
    public void add(){
        System.out.println(1);
    }
}

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