Java static关键字

package cn.lz.base;

/**
 * static关键字
 * @author lzzz
 *
 */
public class J17100803 {
    int id = 1;
    static int idd = 2;
    public static void main(String[] args) {
        J17100803 j1 = new J17100803();
        J17100803 j2 = new J17100803();
        j1.idd += 1;
        j2.idd += 1;
        j1.id += 1;
        j2.id += 1;
        System.out.println(j1.id); // 2
        System.out.println(j1.idd); // 4
        System.out.println(j2.id); // 2
        System.out.println(j2.idd); // 4
        System.out.println(J17100803.idd); // 可以通过ClassName.变量名访问
    }
}

package cn.lz.base;

import static java.lang.Math.*;
/**
 * static关键字
 * @author lzzz
 *
 */
public class J17100803 {
    public static void main(String[] args) {
        System.out.println(abs(-12)); // 12
    }
}