请问String的"不可变性"和"缓冲池特性"是什么意思是啊?

Question

[size=large]我一直到今天都不知道什么意思
还有就是String a = new String("sdsd");
为什么是两个对象啊 究竟是哪两个对象啊[size]

Answer 1

不可变性见string的源码 public final class String 可见string 对象是final的
而且字符只要存储在一个char数组里面
private final char value[]; 这个也是final，所以他是不可变的。
public String(String original) {
int size = original.count;
char[] originalValue = original.value;
char[] v;
if (originalValue.length > size) {
// The array representing the String is bigger than the new
// String itself. Perhaps this constructor is being called
// in order to trim the baggage, so make a copy of the array.
int off = original.offset;
v = Arrays.copyOfRange(originalValue, off, off+size);
} else {
// The array representing the String is the same
// size as the String, so no point in making a copy.
v = originalValue;
}
this.offset = 0;
this.count = size;
this.value = v;
}
这是string的构造函数，很明显可以看出,"sdsd"是参数也是一个String对象，然后new 了一个string对象a,所以是2个对象。