String类中三种实例化对象的区别：

在JDK1.8中

1. String str = "hello"

2. String str = new String("hello")

3. String str = new String(new char[]{'h', 'e', 'l', 'l', 'o'})

---

1.String str = "hello";

---

 2. String str = new String("hello");

---

3. String str = new String(new char[]{'h', 'e', 'l', 'l', 'o'});