Java5種遍歷HashMap資料的寫法
本文介紹了最好的Java5種遍歷HashMap資料的寫法,分享給大家,也給自己留一個筆記,具體如下:
通過EntrySet的迭代器遍歷
Iterator < Entry < Integer,String >> iterator = coursesMap.entrySet().iterator(); while (iterator.hasNext()) { Entry < Integer,String > entry = iterator.next(); System.out.print(entry.getKey() + ". "); System.out.println(entry.getValue()); }
輸出結果如下:
zzw:how_iterate_hashmap_in_java zzw$ java IterateHashMapExample 1
TIOBE Index for March 2020:
1. Java
2. C
3. Python
4. C++
5. C#
6. Visual Basic .NET
7. JavaScript
8. PHP
9. SQL
10. GO
通過KeySet的迭代器遍歷
Iterator < Integer > iterator = coursesMap.keySet().iterator(); while (iterator.hasNext()) { Integer key = iterator.next(); System.out.print(key + ". "); System.out.println(coursesMap.get(key)); }
輸出結果如下:
zzw:how_iterate_hashmap_in_java zzw$ java IterateHashMapExample 2
TIOBE Index for March 2020:
1. Java
2. C
3. Python
4. C++
5. C#
6. Visual Basic .NET
7. JavaScript
8. PHP
9. SQL
10. GO
通過ForEach迴圈遍歷
for (Map.Entry < Integer,String > entry: coursesMap.entrySet()) { System.out.print(entry.getKey() + ". "); System.out.println(entry.getValue()); }
輸出結果如下:
zzw:how_iterate_hashmap_in_java zzw$ java IterateHashMapExample 3
TIOBE Index for March 2020:
1. Java
2. C
3. Python
4. C++
5. C#
6. Visual Basic .NET
7. JavaScript
8. PHP
9. SQL
10. GO
通過Lambda表示式遍歷
coursesMap.forEach((key,value) -> { System.out.print(key + ". "); System.out.println(value); });
輸出結果如下:
zzw:how_iterate_hashmap_in_java zzw$ java IterateHashMapExample 4
TIOBE Index for March 2020:
1. Java
2. C
3. Python
4. C++
5. C#
6. Visual Basic .NET
7. JavaScript
8. PHP
9. SQL
10. GO
通過Stream API遍歷
coursesMap.entrySet().stream().forEach((entry) -> { System.out.print(entry.getKey() + ". "); System.out.println(entry.getValue()); });
輸出結果如下:
zzw:how_iterate_hashmap_in_java zzw$ java IterateHashMapExample 5
TIOBE Index for March 2020:
1. Java
2. C
3. Python
4. C++
5. C#
6. Visual Basic .NET
7. JavaScript
8. PHP
9. SQL
10. GO
完整示例程式碼在這裡
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