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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