java - 字符串池内存分配

Question

String s = "abc";
String s4 = s + "";
System.out.println(s4 == s);
System.out.println(s4.equals(s));

这打印:

false
true

谁能解释一下为什么会这样？

Answer 1

String s="abc"; // goes to string constants pool
String s4 = s +"" ;// has value "abc" but goes on heap and not in string constants pool
System.out.println(s4==s);//well,, the references are not equal. There are 2 diffrent instances with value="abc"
System.out.println(s4.equals(s)); // equals() checks for value and the values of both insatnces are equal.