Java学习拾遗2

话题是由如下的事情引出的： public class StringTest {  public static void main(String[] args) {  String str1 = new String("abc");  String str2 = "abc";  if (str1 == str2) {              System.out.println("str1 == str2");          } else {              System.out.println("str1 != str2");          }  String str3 = "abc";  if (str2 == str3) {              System.out.println("str2 == str3");          } else {              System.out.println("str2 != str3");          }          str1 = str1.intern();  if (str1 == str2) {              System.out.println("str1 == str2");          } else {              System.out.println("str1 != str2");          }  String str4 = new String("abc");          str4 = str4.intern();  if (str1 == str4) {              System.out.println("str1 == str4");          } else {              System.out.println("str1 != str4");          }      }