无法解释程序结果~

[fpwcs]

public class Point {
private int x; // x part of coordinate pair
private int y; // y part of coordinate pair

// no-argument constructor
public Point()
{

}

// constructor
public Point( int xValue, int yValue )
{
// implicit call to Object constructor occurs here
x = xValue; // no need for validation
y = yValue; // no need for validation
}

// set x in coordinate pair
public void setX( int xValue )
{
x = xValue; // no need for validation
}

// return x from coordinate pair
public int getX()
{
return x;
}

// set y in coordinate pair
public void setY( int yValue )
{
y = yValue; // no need for validation
}

// return y from coordinate pair
public int getY()
{
return y;
}

// return String representation of Point object


} // end class Point





// Fig. 9.5: PointTest.java
// Testing class Point.
import javax.swing.JOptionPane;

public class PointTest {

public static void main( String[] args )
{
Point point = new Point( 72, 115 ); // create Point object

// get point coordinates
String output = "X coordinate is " + point.getX() +
"\nY coordinate is " + point.getY();

point.setX( 10 ); // set x-coordinate
point.setY( 20 ); // set y-coordinate

// get String representation of new point value
output += "\n\nThe new location of point is " + point;

JOptionPane.showMessageDialog( null, output ); // display output

System.exit( 0 );

} // end main

} // end class PointTest



为什么执行PointTest后出来的结果是@C17164啊!

[song_ice]

output += "\n\nThe new location of point is " + point;
输出时自动调用point.toString()

[joejoe1991]

重写toString方法：

import javax.swing.JOptionPane; 
 class Point { 
   private int x; // x part of coordinate pair 
   private int y; // y part of coordinate pair 

   // no-argument constructor 
   public Point() 
   { 
       
   }  

   // constructor 
   public Point( int xValue, int yValue ) 
   { 
      // implicit call to Object constructor occurs here 
      x = xValue;  // no need for validation 
      y = yValue;  // no need for validation 
   }  
  
   // set x in coordinate pair 
   public void setX( int xValue ) 
   { 
      x = xValue;  // no need for validation 
   }  

   // return x from coordinate pair 
   public int getX() 
   { 
      return x; 
   }  

   // set y in coordinate pair 
   public void setY( int yValue ) 
   { 
      y = yValue;  // no need for validation 
   }  

   // return y from coordinate pair 
   public int getY() 
   { 
      return y; 
   }  

	/**
		这里重写了toString()方法
	*/
   public String toString() {
		return this.x+","+this.y;
   }

   // return String representation of Point object 


} // end class Point 


// Fig. 9.5: PointTest.java 
// Testing class Point. 


public class Main { 

   public static void main( String[] args )  
   { 
      Point point = new Point( 72, 115 );  // create Point object 

      // get point coordinates 
      String output = "X coordinate is " + point.getX() + 
         "\nY coordinate is " + point.getY(); 
       
      point.setX( 10 );  // set x-coordinate 
      point.setY( 20 );  // set y-coordinate 

      // get String representation of new point value 
      output += "\n\nThe new location of point is " + point; 

      JOptionPane.showMessageDialog( null, output ); // display output 

      System.exit( 0 ); 

   } // end main 

} // end class PointTest 

[anqini]

output += "\n\nThe new location of point is " + point;
因为一个对象遇到字符串相加的时候自动调用其toString方法！但是你没有重写toString!自己重写把！

[fpwcs]

那请问出的结果又为什么是@C17164这个呢>?

[KKK2007]

为什么执行PointTest后出来的结果是@C17164啊!
point是个对象，你直接这样output += "\n\nThe new location of point is " + point;
实际上输出的@C17164是 point对象的引用地址。
要想输出point的坐标，如楼上说，你要重写toString,或者写个别的方法输出点坐标

[anqini]

[Quote=引用 4 楼 fpwcs 的回复:]
那请问出的结果又为什么是@C17164这个呢>?
[/Quote]

toString()如下！

getClass().getName() + '@' + Integer.toHexString(hashCode())

@C17164，前面是不是还输出了你的类名字？？清楚了吧！

[joejoe1991]

Object类的toString()方法，默认返回的是：类名+@+十六进制的哈希码
也就是：
getClass().getName()+"@"+Integer.toHexString(this.hashCode());

我们应该重写这个方法，让它返回一个更具有意义的字符串。

[&永无止境]

可以参见http://topic.csdn.net/u/20080423/13/4707b290-a5ea-4cfe-b5fa-b9b9c585c3c1.html如果没有重写toString()方法就调用Object类的toString()方法,@C17164就是调用Object类的toString()方法的结果

[likai22]

太长了