目录
1、提出问题
2、源码分析
3、测试Demo：
1、提出问题
我们都知道，在Java中，“==”比较的是对象在内存中的地址，“equals”比较对象的内容；今天复习一下”equals“。
2、源码分析
/**
* Compares this string to the specified object. The result is {@code
* true} if and only if the argument is not {@code null} and is a {@code
* String} object that represents the same sequence of characters as this
* object.
*
* @param anObject
* The object to compare this {@code String} against
*
* @return {@code true} if the given object represents a {@code String}
* equivalent to this string, {@code false} otherwise
*
* @see #compareTo(String)
* @see #equalsIgnoreCase(String)
*/
public boolean equals(Object anObject) {
//First：比较两个对象是否是同一个对象，则直接return true；
if (this == anObject) {
return true;
}
//Second：如果被比较的对象是String类型，则继续
if (anObject instanceof String) {
String anotherString = (String)anObject;
int n = value.length;
//Third：比较两者的长度
if (n == anotherString.value.length) {
char v1[] = value;
char v2[] = anotherString.value;
int i = 0;
//Forth：比较两者元素是否相同
while (n-- != 0) {
if (v1[i] != v2[i])
return false;
i++;
}
return true;
}
}
return false;
}
3、测试Demo：
public class test_equals {
public static void main(String[] args) {
// TODO Auto-generated method stub
String a="1234";
String b="1234";
String c = new String("1234");
System.out.println("a==b: "+(a==b));
System.out.println("a==c: "+(a==c));
System.out.println("a.equals(c): "+(a.equals(c)));
}
}
console：
a==b: true
a==c: false
a.equals(c): true
