1.单例
package com.yfs.javase;
public class Singleton {
//private static final Singleton single = new Singleton();//定义自己的对象引用
private static Singleton single;
// 控制构造方法
private Singleton() {
}
// 提供获取对象的方法
public static Singleton getInstance() {
if(single == null) {
System.out.println("创建Singleton对象....");
single = new Singleton();
}
return single;
}
public void sayHello() {
System.out.println("Hello....");
}
}
2.单例测试
package com.yfs.javase;
public class SingleTest {
public static void main(String[] args) {
// Singleton s1 = new Singleton();
// s1.sayHello();
//
// Singleton s2 = new Singleton();
// s2.sayHello();
//
// final int a = 10;
//a = 20;
// System.out.println("s1 == s2 : " + (s1 == s2));
Singleton s1 = Singleton.getInstance();
Singleton s2 = Singleton.getInstance();
s1.sayHello();
s2.sayHello();
System.out.println("s1 == s2 : " + (s1 == s2));
}
}
3.开关灯示例
package com.yfs.javase;
public class Light {
// 属性编号 状态
private int index;
private boolean lighting = true;
// 构造方法
public Light(int index) {
this.index = index;
setIndex(index);
}
// 查看状态方法
public boolean isLighting() {
return lighting;
}
// 获取灯的编号
public int getIndex() {
return index;
}
// 根据编号设置灯的状态
private void setIndex(int index) {
for (int i = 1; i < index; i++) {
if (index % i == 0) {
// if (lighting) {//== true
// lighting = false;
// } else {
// lighting = true;
// }
// lighting = lighting ? false : true;
lighting = !lighting;
}
}
}
}
4.灯测试
package com.yfs.javase;
public class LightTest {
public static void main(String[] args) {
//灯数组
Light[] lights = new Light[100];
//创建对象
for (int i = 0; i < lights.length; i++) {
lights[i] = new Light(i + 1);
}
//查看灯的状态
for (int i = 0; i < lights.length; i++) {
//灯类必须查看状态方法
if(lights[i].isLighting()){
System.out.println("第 " + lights[i].getIndex() + " 灯是亮的");
}
}
}
}
5.乘法表
package com.yfs.javase;
public class Demo {
private Demo() {
}
public static Demo get() {
return new Demo();
}
public static void main(String[] args) {
for (int i = 1,j = 1; i < 10; ) {
System.out.print(j + " * " + i + " = " + (i * j) + " ");
j++;//让列增长
if(j == i + 1) {
j = 1;
System.out.println();
i++;//行增长
}
}
}
}