菜鸟求助

[JavaLittleStudent]

package cn.guangzhou.xp;

class Person {

private int age;
private int x;

public Person(int age){

age = x;
}

public Person() {

}

public void setAge(int x) {

if (age <= 0) {
return;
} else {
age = x;
}
}

public int getAge() {
return age;
}

void shout() {
System.out.println("My age is " + age);
}

public static void main(String[] args) {

Person p1 = new Person();
Person p2 = new Person();

p1.setAge(5);
p1.shout();

p2.age = -1;
p2.shout();

}

}


输出结果为什么是0跟-1 而不是5跟0
错在哪里了？要怎么改？

[uastation]

类的成员变量...在函数中改变了他的值,不会影响到他真正的值的..

[Acesidonu]

注意局部变量和成员变量的区别

[AoYuanSE]

p1的时候

if (age <= 0) {
return;
} else {
age = x;
}
}

age本来就是0啊

[AoYuanSE]

if (age <= 0) {
return;
} else {
age = x;
}
}

你把age<=0 改成age<=-1 就能得到你的结果了

[艳沐石]

setAge的时候，你应该验证的是，传输参数是否大于0吧


应该是这样吧？
if (x <= 0)
return;
else
age = x;

[Fishing_Moon]

public Person(int age){
this.age = age;
this.x = x;
}

public void setAge(int age) {
if (age <= 0) {
return;
} else {
age = x;
}
}

输出结果可以得到你要的结果

[Fishing_Moon]

public Person(int age,int x){
this.age = age;
this.x = x;
}

public void setAge(int age) {
if (age <= 0) {
return;
} else {
age = x;
}
}

[脉动]

package cn.guangzhou.xp;

class Person {
	private int age;
	private int x;


	public Person(int age)
	{
		age = x; //这边age指的不是Person类的age成员变量，而是指你传进来的参数age;
		         //可以写成: this.age = age;
	}

	public Person() 
	{
	}

	public void setAge(int x) 
	{
		if(age <= 0) // 这边用age来判断，此时age的值是0（默认初始化的），所以符合判断条件，
		{            //执行return语句，返回，再调用shout()方法，输出（age的值是0）：My age is 0
			return;    
		} 
		else 
		{
			age = x;
		}
	}

	public int getAge() 
	{
		return age;
	}

	void shout() 
	{
		System.out.println("My age is " + age);
	}

	public static void main(String[] args) 
	{
		
		Person p1 = new Person();
		Person p2 = new Person();
		
		p1.setAge(5);
		p1.shout();
		
		p2.age = -1;
		p2.shout();
	
	}

}