变量初始化的顺序

朴灿烈づ我的快乐病毒、 2023-06-11 08:29 10阅读 0赞

# 变量初始化的顺序问题 #

看java编程思想，在变量初始化过程中有点绕，摘出来，记录下。

/**
     * 定义一个bowl类
     *
     * @author 吧嘻小米
     * @since 1.0-SNAPSHOT
     */
    public class Bowl {
        
        public Bowl(int marker) {
        
            System.out.println("Bowl(" + marker + ")");
        }
    
        public void f1(int marker) {
        
            System.out.println("f1(" + marker + ")");
        }
    }

/**
     * 定义一个cupboard类
     *
     * @author 吧嘻小米
     * @since 1.0-SNAPSHOT
     */
    public class Cupboard {
        
        static Bowl bowl4 = new Bowl(4);
        static Bowl bowl5 = new Bowl(5);
        Bowl bowl3 = new Bowl(3);
    
        public Cupboard() {
        
            System.out.println("cupboard()");
            bowl4.f1(2);
        }
    
        public void f3(int marker) {
        
            System.out.println("f3(" + marker + ")");
        }
    }

/**
     * 定义table类
     *
     * @author 吧嘻小米
     * @since 1.0-SNAPSHOT
     */
    public class Table {
        
        static Bowl bowl1 = new Bowl(1);
        static Bowl bowl2 = new Bowl(2);
    
        public Table() {
        
            System.out.println("Table()");
            bowl2.f1(1);
        }
    
        public void f2(int marker) {
        
            System.out.println("f2(" + marker + ")");
        }
    }

/**
     * 变量初始化的顺序演示
     *  * @author 吧嘻小米
     * @since 1.0-SNAPSHOT
     */
    public class StaticInitialization {
        
    
        static Table table = new Table();
        static Cupboard cupboard = new Cupboard();
    
        public static void main(String[] args) {
        
            System.out.println("create new Cupboard() in main");
            new Cupboard();
            System.out.println("Create new Cupboard() in main");
            new Cupboard();
            table.f2(1);
            cupboard.f3(1);
        }/*Output:
         Bowl(1)
         Bowl(2)
         Table()
         f1(1)
         Bowl(4)
         Bowl(5)
         Bowl(3)
         cupboard()
         f1(2)
         create new Cupboard() in main
         Bowl(3)
         cupboard()
         f1(2)
         Create new Cupboard() in main
         Bowl(3)
         cupboard()
         f1(2)
         f2(1)
         f3(1)
        *///:~
    }

小结：

*  变量的初始化顺序，静态变量–>其他变量；
 *  只有当一个变量完成全部的初始化(包括静态变量的初始化，构造方法的完成等)才会顺序执行下一个变量的初始化；
 *  静态变量只会初始化一次，非静态变量会被初始化多次;
 *  静态变量只有在被调用时才会初始化。