Interview question: the difference between three instantiated objects in string class

String The difference between the three instantiated objects in the class ：

stay JDK1.8 in

1. String str = "hello"

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

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

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1.String str = "hello";

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 2. String str = new String("hello");

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

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