Java - static的注意点

静态函数与静态变量无需生成对象

静态函数只能调用静态变量

装载类的时候执行静态代码块

静态函数中不能使用this

/*
 * For test static
 * 2014-10-26
 */
public class JavaTest  {
	public static void main(String args[]){
		TestStatic.i = 10;	//第一次赋值,未创建对象
		TestStatic T1 = new TestStatic();
		TestStatic T2 = new TestStatic();	//创建两个对象
		System.out.println("The T1.i = " + T1.i);
		System.out.println("The T2.i = " + T2.i);
		T1.i = 20;	//给其中一个对象的i赋值
		System.out.println("Change the value of T1.i");
		System.out.println("The T1.i = " + T1.i);
		System.out.println("The T2.i = " + T2.i);
		TestStatic.method1();	//查看目前的i值
	}
}

class TestStatic{
	static int i;
	static String arg1;
	static{
		System.out.println("Now loading the 'TestStatic' class");
	}
	static void method1(){
		System.out.println("The current i is " + i);
	}
}

输出结果：

Now loading the 'TestStatic' class
The T1.i = 10
The T2.i = 10
Change the value of T1.i
The T1.i = 20
The T2.i = 20
The current i is 20

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装载TestStatic类时，打印出了Now loading the 'TestStatic' class。对static int i赋值10，对象i的值都是10。

改变i的值，TestStatic对象的i值都会变。