对参数不是很懂，希望大神帮忙。问题注释在代码中（此处有参和无参的区别是什么）

package jiaoChen;

public class Private {
private float screen;
private float cpu;
private float mem;

public float getScreen() {
    return screen;
}
public void setScreen(float scree) {
    this.screen = scree;
}
public float getCpu() {
    return cpu;
}
public void setCpu(float cpu){
    this.cpu = cpu;
}
public float getMem() {
    return mem;
}
public void setMem(float mem) {
    this.mem = mem;
}
public Private() {
    System.out.println("Prvite无参的构造方法执行了");
}
public Private(float newScreen,float newCpu,float newMem) {
    screen = newScreen;
    cpu = newCpu;
    mem = newMem;
    System.out.println("有参的构造方法执行了");
}

}
//下面是另外一个程序了
package jiaoChen;

public class PrivateText {
public static void main(String[] args) {

    //通过无参的构造方法可以创建对象
    Private phone = new Private();
    phone.setCpu(2.0f);
    System.out.println("cpu = " + phone.getCpu());

    //通过有参的构造方法可以创建对象，并给对象中的实例化变量赋初值
    Private phone2 = new Private(5.0f,1.4f,2.0f);               //此处有参和无参的区别是什么
    phone2.setScreen(6.0f);
    System.out.println("screen" + phone2.getScreen());
    phone2.setCpu(4.0f);
    System.out.println("mem = " + phone2.getCpu());
    phone2.setMem(3.0f);
    System.out.println("mem = " + phone2.getMem());

}

}

http://blog.csdn.net/high2011/article/details/50788488
http://blog.csdn.net/manong_xiaojiang/article/details/7820547

无参构造方法的对象没有初始化其属性

一个Person类(比如包含 name age 等属性),
比如你用无参构造new了一个Person类的对象 person,
Person person = new Person(),
,你用person.getName()获得的是null,

而你有参构造new 对象 ,
Person person1 = new Person("小黄",10);
那么你person1.getName() 会得到 "小黄",

祝学习进步!

Private phone2 = new Private(5.0f,1.4f,2.0f); 调用并赋值。。
screen = newScreen;
cpu = newCpu;
mem = newMem;
System.out.println("有参的构造方法执行了");

如果是无参数，那就是调用的默认构造函数。。
System.out.println("Prvite无参的构造方法执行了");

这是多重构造函数，根据参数来确定调用哪个构造函数
Person person = new Person() 参数和这个构造函数匹配，就调用它
public Private() {
System.out.println("Prvite无参的构造方法执行了");
}
phone2 = new Private(5.0f,1.4f,2.0f); 参数和下边的构造函数匹配，调用这个构造函数

public Private(float newScreen,float newCpu,float newMem) {
screen = newScreen;
cpu = newCpu;
mem = newMem;
System.out.println("有参的构造方法执行了");
}