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public class StringTest {    public static void main(String[] args) { String s0 = new String("abc");//此语句产生几个String object String s1 = "abc";//此语句产生几个String object String s2 = new String("abc");//此语句产生几个String object String s3 = "abc"; System.out.println(s0 == s1);//输出true or false System.out.println(s0 == s2);//输出true or false System.out.println(s1 == s2);//输出true or false System.out.println(s1 == s3);//输出true or false System.out.println(s1 == s0.intern());//输出true or false System.out.println(s1 == s1.intern());//输出true or false System.out.println(s1 == s2.intern());//输出true or false String hello = "hello"; String hel = "hel"; String lo = "lo"; System.out.println(hello == "hel" + "lo");//输出true or false System.out.println(hello == "hel" + lo);//输出true or false } }