java学习笔记（四）面向对象

package wbb.java.JavaObject;

/**
 * Created with IntelliJ IDEA.
 * User: wbb
 * Date: 14-7-17
 * Time: 下午4:26
 * To change this template use File | Settings | File Templates.
 */
public class MulParams {
    public static void main(String[] args) {
        mulFun("篮球", "足球");
    }

    public static void mulFun(String... ballName) {
        for(String name : ballName) {
            System.out.println(name);           
        }
    }
}

二、方法重载

package wbb.java.JavaObject;

/**
 * Created with IntelliJ IDEA.
 * User: wbb
 * Date: 14-7-21
 * Time: 上午9:31
 * To change this template use File | Settings | File Templates.
 */
public class OverWrite {
    public static void main(String[] args) {
        B b = new B();
        b.test();
    }
}

class A {
    public String name = "wbb";
    public void test() {
        System.out.println("父类test方法");
    }
}

class B extends A {
    public void test() {
        System.out.println(super.name);
        super.test();
    }
}

package wbb.java.JavaObject;

/**
 * Created with IntelliJ IDEA.
 * User: wbb
 * Date: 14-7-23
 * Time: 上午9:31
 * To change this template use File | Settings | File Templates.
 */
public class ToString {
    public static void main(String[] args) {
        Animal animal = new Animal("忠犬八公");
        System.out.println(animal);
    }
}

class Animal {
    private String name;
    public Animal(String name) {
        this.name = name;
    }

//    public String toString() {
//        return "这条狗的名字为" + name;
//    }
}

package wbb.java.JavaObject;

/**
 * Created with IntelliJ IDEA.
 * User: wbb
 * Date: 14-7-25
 * Time: 下午3:30
 * To change this template use File | Settings | File Templates.
 */
public class Singleton {
    //定义一个静态的变量用于缓存创建过的实例
    private static Singleton instance;

    //为了避免其它类自由创建该类的实例。把构造器声明为私有的，仅仅有在该类内部才干调用构造器
    private Singleton(){}

    // 提供一个public方法作为该类的訪问点，而且必须使用static修饰。

    // 由于调用该方法之前还不存在对象。因此调用该方法的不可能是对象，仅仅能是类。
    // 由于成员变量在静态方法中使用，所以定义的时候用static修饰。
    public static Singleton getInstance() {
        if(instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}

class TestSingleton {
    public static void main(String[] args) {
        Singleton instance1 = Singleton.getInstance();
        Singleton instance2 = Singleton.getInstance();
        //输出结果为true，说明两个引用变量指向的是同一个对象
        System.out.println(instance1 == instance2);
    }
}