當需要將一個對象輸出到顯示器時,通常要調用他的toString()方法,將對象的內容轉換為字符串.java中的所有類默認都有一個toString()方法
默認情況下 System.out.println(對象名)或者System.out.println(對象名.toString())輸出的是此對象的類名和此對象對應內存的首地址 如果想自定義輸出信息必須重寫toString()方法
注意事項
1.必須被聲明為public
2.返回類型為String
3.方法的名稱必須為toString,且無參數
4.方法體中不要使用輸出方法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; } |
輸出為:
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[Item@8c9e3a56, Item@d780c206, Item@39c021ba][Item@39c021ba, Item@8c9e3a56, Item@d780c206] |
Item重載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; } |
輸出為:
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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]] |
總結
以上就是本文關于java tostring方法重寫代碼示例的全部內容，希望對大家有所幫助。有問題您可以留言，歡迎大家交流討論。
原文鏈接：http://blog.csdn.net/tzasd89812/article/details/21371661
