Java, lesser-known small ideas

1. Nonsense perhaps you have already heard disputes goto statement, goto know that in Java, is still a reserved keyword, but are not allowed. Let's look at the classic use goto:

1: statement1; 

2: statement_label_for_section2: 

3: statement2; 

4: goto statement_label_for_section2;

You can see 2: statement_label_for_section2: a code fragment (Section) of the opening tag.

Java language does not allow use of goto, but you can use as 2: statement_label_for_section2: the same code fragment labeled as break / continue the jump target.

See documents related standards: <> 14.7 Labeled Statements

2. Application of nested loops, I sometimes need to jump from outside the inner loop in the loop. Labeled Statements can be used to facilitate the achievement.

1: for (int I1 = 0; I1 <10; I1 + +) ( 

2: loop1: 

3: for (int I2 = 0; I2 <20; I1 + +) ( 

4: break loop1; 

5:) 

6:)

continue to use and the use of break is the same.

Java language is not widely used in many small ideas. See: <>

3.Blocks 

<> 14.2 Blocks

Perhaps you are a slacker like me. Among the special code in the Test Case, I often need to define a lot of the same Method object, these objects are similar in major operations, you should know what I was thinking: Copy & Past. And for each object from a different name can be a pain to do. At the same time these objects are often only short-lived Ghost.

1: import java.util.ArrayList; 

2: import java.util.Collection; 

3: 

4: public class T2 ( 

5: 

6: public static void main (String [] args) ( 

7: ( 

8: Collection c = new ArrayList (); 

9: c.add ("1"); 

10: c.clear (); 

11:) 

12: ( 

13: Collection c = new ArrayList (); 

14: c.add ("2"); 

15: c.clear (); 

16:) 

17:) 

18: 

19:)