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public class StringTest1{
  public static void main(String[] args) {
     String str1 = "abc";
     String str2 = "abc";
     System.out.println(str1 == str2);
   }
}
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public class StringTest2 {
   public static void main(String[] args) {
     String str1 = new String("abc");
     String str2 = new String("abc");
     System.out.println(str1 == str2);
  }
}
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Effective Java¶ÁÊé±Ê¼Ç

package chape8;
import java.math.BigDecimal;
/**
* 8-48
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