public boolean equals(Object obj) 
 { 
 return (this == obj); 
 }

public boolean equals(Object anObject)
{ 
//先進(jìn)行地址值的判斷，如果想等直接返回true 
if (this == anObject) 
{ 
return true; 
} 
//如果地址不相等，判斷傳進(jìn)來的對(duì)象是不是String類型的一個(gè)實(shí)例 
if (anObject instanceof String) 
{ 
//發(fā)現(xiàn)是string類型的實(shí)例，將它強(qiáng)轉(zhuǎn)為string類型(強(qiáng)轉(zhuǎn)之后就可以調(diào)用string的方法了) 
String anotherString = (String) anObject; 
//value是string內(nèi)部的一個(gè)char數(shù)組，每個(gè)string對(duì)象都對(duì)應(yīng)一個(gè)char數(shù)組，得到長度 
int n = value.length; 
//先進(jìn)行長度的比較，如果相同才能進(jìn)行下一步 
if (n == anotherString.value.length) 
{ 
//發(fā)現(xiàn)長度相同，將string對(duì)應(yīng)的char數(shù)組中的字符一個(gè)一個(gè)進(jìn)行比較 
char v1[] = value; 
char v2[] = anotherString.value; 
int i = 0; 
while (n-- != 0) {  
if (v1[i] != v2[i])  
return false;  
i++; 
} 
return true; 
} 
} 
return false; 
}

public class TestString {
 public static void main(String[] args) {
  String s1 = "Monday";
  String s2 = "Monday";
  if (s1 == s2)
 {
  System.out.println("s1 == s2");}
  else{
System.out.println("s1 != s2");}
 }
 }

public class TestString {
public static void main(String[] args) {
String s1 = "Monday";
String s2 = new String("Monday");
if (s1 == s2)
{System.out.println("s1 == s2");}
else
{System.out.println("s1 != s2");}
if (s1.equals(s2)) {System.out.println("s1 equals s2");}
else{
System.out.println("s1 not equals s2");}
}
}