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java入门第二季--第1章类和对象--java中的构造方法

构造方法写法

构造方法特征

java入门第二季--第1章类和对象--java中的构造方法

无参的构造方法

/javaDemo2/src/com/imooc/Telphone.java

package com.imooc;

public class Telphone {
    public Telphone() {
        System.out.println("无参的构造方法");
    }

}

/javaDemo2/src/com/imooc/InitailTelphone.java

package com.imooc;

public class InitailTelphone {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Telphone phone =new Telphone();
    }

}

有参的构造方法

/javaDemo2/src/com/imooc/Telphone.java

package com.imooc;

import com.sun.glass.ui.Screen;

public class Telphone {
    float screen;
    float cpu;
    public Telphone() {
        System.out.println("无参的构造方法");
    }
    
    public Telphone(float newScreen,float newCpu) {
        screen = newScreen;
        cpu = newCpu;
        System.out.println("有参的构造方法");
    }
}

/javaDemo2/src/com/imooc/InitailTelphone.java

package com.imooc;

public class InitailTelphone {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Telphone phone =new Telphone();
        Telphone phone2 =new Telphone(5.0f,1.4f);
    }

}

构造方法给对象的属性一个合理的值

/javaDemo2/src/com/imooc/Telphone.java

package com.imooc;

import com.sun.glass.ui.Screen;

public class Telphone {
    float screen;
    float cpu;
    public Telphone() {
        System.out.println("无参的构造方法");
    }
    
    public Telphone(float newScreen,float newCpu) {
        if(newScreen <3.5f) {
            System.out.println("你的参数有误");
            screen = 3.5f;
        }
        screen = newScreen;
        cpu = newCpu;
        System.out.println("有参的构造方法");
    }
}

/javaDemo2/src/com/imooc/InitailTelphone.java

package com.imooc;

public class InitailTelphone {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Telphone phone =new Telphone();
        Telphone phone2 =new Telphone(1.5f,1.4f);
    }

}