当需要将一个对象输出到显示器时,通常要调用他的toString()方法,将对象的内容转换为字符串.java中的所有类默认都有一个toString()方法
默认情况下 System.out.println(对象名)或者System.out.println(对象名.toString())输出的是此对象的类名和此对象对应内存的首地址 如果想自定义输出信息必须重写toString()方法
注意事项
1.必须被声明为public
2.返回类型为String
3.方法的名称必须为toString,且无参数
4.方法体中不要使用输出方法System.out.println()
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import java.util.*; public class TreeSetTest { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub SortedSet<Item> parts= new TreeSet<Item>(); parts.add( new Item( "Toaster" , 1234 )); parts.add( new Item( "Widget" , 4562 )); parts.add( new Item( "Modem" , 9912 )); System.out.println(parts); SortedSet<Item> sortByDescription= new TreeSet<Item>( new Comparator<Item>() { public int compare(Item a, Item b) { String descrA=a.getDescription(); String descrB=b.getDescription(); return descrA.compareTo(descrB); } }); sortByDescription.addAll(parts); System.out.println(sortByDescription); } } class Item implements Comparable<Item> { public Item(String aDescription, int aPartNumber) { description=aDescription; partNumber=aPartNumber; } public String getDescription() { return description; } public boolean equals(Object otherObject) { if ( this ==otherObject) return true ; if (otherObject== null ) { return false ; } if (getClass()!=otherObject.getClass()) { return false ; } Item other=(Item)otherObject; return description.equals(other.description)&& partNumber==other.partNumber; } public int hashCode() { return 13 *description.hashCode()+ 17 *partNumber; } public int compareTo(Item other) { return partNumber-other.partNumber; } private String description; private int partNumber; } |
输出为:
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[Item @8c9e3a56 , Item @d780c206 , Item @39c021ba ] [Item @39c021ba , Item @8c9e3a56 , Item @d780c206 ] |
Item重载toString()方法后:
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import java.util.*; public class TreeSetTest { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub SortedSet<Item> parts= new TreeSet<Item>(); parts.add( new Item( "Toaster" , 1234 )); parts.add( new Item( "Widget" , 4562 )); parts.add( new Item( "Modem" , 9912 )); System.out.println(parts); SortedSet<Item> sortByDescription= new TreeSet<Item>( new Comparator<Item>() { public int compare(Item a, Item b) { String descrA=a.getDescription(); String descrB=b.getDescription(); return descrA.compareTo(descrB); } }); sortByDescription.addAll(parts); System.out.println(sortByDescription); } } class Item implements Comparable<Item> { public Item(String aDescription, int aPartNumber) { description=aDescription; partNumber=aPartNumber; } public String getDescription() { return description; } public String toString() { return "[description=" +description + ",partNumber=" +partNumber+ "]" ; } public boolean equals(Object otherObject) { if ( this ==otherObject) return true ; if (otherObject== null ) { return false ; } if (getClass()!=otherObject.getClass()) { return false ; } Item other=(Item)otherObject; return description.equals(other.description)&& partNumber==other.partNumber; } public int hashCode() { return 13 *description.hashCode()+ 17 *partNumber; } public int compareTo(Item other) { return partNumber-other.partNumber; } private String description; private int partNumber; } |
输出为:
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[[description=Toaster,partNumber= 1234 ], [description=Widget,partNumber= 4562 ], [description=Modem,partNumber= 9912 ]] [[description=Modem,partNumber= 9912 ], [description=Toaster,partNumber= 1234 ], [description=Widget,partNumber= 4562 ]] |
总结
以上就是本文关于java tostring方法重写代码示例的全部内容,希望对大家有所帮助。有问题您可以留言,欢迎大家交流讨论。
原文链接:http://blog.csdn.net/tzasd89812/article/details/21371661