直接上问题模拟和总结:
import java.io.*;
public class Main {
public static void main(String[] args) {
String a = "abc";
String b = "abc";
String c = null;
System.out.println(a == b);
a = new String("abc");
b = new String("abc");
System.out.println(a == b);
//将"abc"序列化在字节数组中
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
try {
ObjectOutputStream outt = new ObjectOutputStream(byteArrayOutputStream);
outt.writeObject("abc");
outt.writeObject("abc");
} catch (IOException e) {
e.printStackTrace();
}
//从字节数组中反序列化"abc"
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
try {
ObjectInputStream inn = new ObjectInputStream(byteArrayInputStream);
b = (String) inn.readObject();
c = (String) inn.readObject();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
System.out.println(a == b);
System.out.println(a.equals(b));
a = c;
System.out.println(a == b);
//将"abc"序列化在字节数组中
ByteArrayOutputStream byteArrayOutputStream1 = new ByteArrayOutputStream();
try {
ObjectOutputStream outt = new ObjectOutputStream(byteArrayOutputStream1);
outt.writeObject("abc");
} catch (IOException e) {
e.printStackTrace();
}
//从字节数组中反序列化"abc"
ByteArrayInputStream byteArrayInputStream1 = new ByteArrayInputStream(byteArrayOutputStream1.toByteArray());
try {
ObjectInputStream inn = new ObjectInputStream(byteArrayInputStream1);
a = (String) inn.readObject();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
System.out.println(a == b);
}
}
结果:
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLiAzNvwVZ2x2bzNXak9CX90TQNNkRrFlQKBTSvwFbslmZvwFMwQzLcVmepNHdu9mZvwFVywUNMZTY18CX052bm9CX00EVOhXWq1kMNpHW4Z0MMBjVtJWd0ckW65UbM5WOHJWa5kHT20ESjBjUIF2LcRHelR3LcJzLctmch1mclRXY39DO2IjNyQzM2EDMxcDM4EDMy8CX0Vmbu4GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.jpg)
总结:
1、String对象通过""创建时,统一指向方法区中的运行时常量池,所以内容相同时,地址也相同
2、String对象通过new创建(禁止,浪费性能),会先在常量池创建常量,然后在堆中创建对象,两个对象内容相同地址不同,共建三个对象
后面这几条为推测,若有大神,跪求指点:
3、反序列化得的String对象创建在堆里,跟常量池中对象比较时,出现内容相同,地址不同的情况
4、同一个源反序列化得到的具备相同内容的String对象,地址也相同。(求解原因)
5、不同源反序列化得到的具备相同内容的String对象,地址不同。(求解原因)