javaÖÐ== ÓëequalsµÄÇø±ð
public class test1
{
public static void main(String[] args){
//== ÓëequalsµÄÇø±ð
//1.nullµÄ±È½Ï£ºÖ»ÄÜÓÃ==
System.out.println("1.nullµÄ±È½Ï£ºÖ»ÄÜÓÃ==");
Object o1=null,o2=null;
System.out.println(null==null&&o1==null&&o1==o2);//true
//System.out.println(o1.equals(o2)) //Å׳öÒì³£
//2.»ù±¾ÀàÐ͵ıȽϣºÖ»ÄÜÓÃ==
System.out.println("\n\n2.»ù±¾ÀàÐ͵ıȽϣºÖ»ÄÜÓÃ==");
double i=2.4,j=2.4;
System.out.println(i==j);//true
//3.ÒýÓõıȽϣºµ±×ÓÀàÖØд¹ýequalsÖ®ºó£¬ ==ÓëequalsµÄ±È½ÏЧ¹û²¢²»Í¬£¬e.g String
//==Ï൱ÓÚ×îÔʼµÄequals
/*¸ùÀàObjectÓÐÈçÏ´úÂë
* public boolean equals(Object obj) {
* return (this == obj);
* }
* */
System.out.println("\n\n3.ÒýÓõıȽϣº" +
"µ±×ÓÀàÖØд¹ýequalsÖ®ºó£¬ ==ÓëequalsµÄ±È½ÏЧ¹û²¢²»Í¬£¬e.g String");
String str1=new String("string"),str2=new String("string"),str3=str1;
System.out.println(str3==str1&&str3.equals(str1));//Ö¸Ïòͬһ¶ÔÏó£¬true
System.out.println(str1==str2);//²¢²»Ö¸Ïòͬһ¸ö¶ÔÏó£¬false
System.out.println(str1.equals(str2));//ÓÉÓÚequals±»ÖØдÁË£¬
//Ö»±È½Ï ËûÃǵÄÖµ£¬ËùÒÔ±¾Àý·µ»Øtrue
//4.×¢ÒâµÄµØ·½,new String() ÓëÖØÔØ·ûºÅ=µÄÇø±ð
System.out.println("\n\n4.×¢ÒâµÄµØ·½,new String() ÓëÖØÔØ·ûºÅ=µÄÇø±ð");
System.out.println("string"=="string");//·µ»Øtrue,˵Ã÷Ö¸ÏòµÄÊÇͬһ¸ö¶ÔÏó
System.out.println(new String("string")=="string");//·µ»Øfalse
}
}
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public class EasyError1 {
class Student {
private String name;
public String getName() {
......