1. 应用try-with-resources简化文件读取操作:
批改前:
FileInputStream fis = null;try { fis = new FileInputStream("file.txt"); // ...} catch (FileNotFoundException e) { e.printStackTrace();} finally { if (fis != null) { try { fis.close(); } catch (IOException e) { e.printStackTrace(); } }}
批改后:
try (FileInputStream fis = new FileInputStream("file.txt")) { // ...} catch (IOException e) { e.printStackTrace();}
2. 应用Lambda表达式简化汇合操作:
批改前:
List<String> names = Arrays.asList("Alice", "Bob", "Charlie");for (String name : names) { System.out.println(name);}
批改后:
List<String> names = Arrays.asList("Alice", "Bob", "Charlie");names.forEach(name -> System.out.println(name));
3. 应用StringBuilder类拼接字符串:
批改前:
String s = "";for (int i = 0; i < 10; i++) { s += i;}
批改后:
StringBuilder sb = new StringBuilder();for (int i = 0; i < 10; i++) { sb.append(i);}String s = sb.toString();
4. 应用动态导入简化代码:
批改前:
System.out.println(Math.sqrt(2));
批改后:
import static java.lang.Math.sqrt;System.out.println(sqrt(2));
5. 应用断言简化调试:
批改前:
if (x < 0) { throw new IllegalArgumentException("x must be non-negative");}
批改后:
assert x >= 0 : "x must be non-negative";
6. 应用Optional类解决可能为空的对象:
批改前:
String s = null;if (s != null) { System.out.println(s.length());}
批改后:
Optional<String> optional = Optional.ofNullable(null);optional.ifPresent(s -> System.out.println(s.length()));
7. 应用枚举类代替常量:
批改前:
public static final int STATUS_NEW = 0;public static final int STATUS_PROCESSING = 1;public static final int STATUS_COMPLETED = 2;
批改后:
public enum Status { NEW, PROCESSING, COMPLETED}
8. 应用自定义异样类代替通用异样类:
批改前:
try { // ...} catch (Exception e) { e.printStackTrace();}
批改后:
try { // ...} catch (MyCustomException e) { e.printStackTrace();}
9. 应用Lambda表达式和Stream API简化汇合操作:
批改前:
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);List<Integer> evenNumbers = new ArrayList<>();for (int number : numbers) { if (number % 2 == 0) { evenNumbers.add(number); }}
批改后:
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);List<Integer> evenNumbers = numbers.stream()
10. 应用ThreadLocal防止线程平安问题:
批改前:
public class MyRunnable implements Runnable { private int count = 0; public void run() { for (int i = 0; i < 100000; i++) { count++; } System.out.println(count); }}
批改后:
public class MyRunnable implements Runnable { private ThreadLocal<Integer> count = new ThreadLocal<Integer>() { @Override protected Integer initialValue() { return 0; } }; public void run() { for (int i = 0; i < 100000; i++) { count.set(count.get() + 1); } System.out.println(count.get()); }}
在多线程环境下,应用一般的成员变量会导致线程平安问题,而应用ThreadLocal能够确保每个线程拜访的变量是独立的,防止了线程平安问题。在下面的示例中,应用ThreadLocal确保了每个线程拜访的count变量是独立的,从而防止了线程平安问题。
结尾
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