Java : Throwable 示例

Throwable (Java SE 22 & JDK 22) 示例。
您将在大多数 Throwable 方法中找到代码示例。

注解 :

本文可能使用了翻译软件以方便阅读。另请查看英文原文。

简介

Throwable 类是 Java 语言中所有错误和异常的超类。只有此类（或其子类之一）的实例对象才会被 Java 虚拟机抛出，或者可以通过 Java throw 语句抛出。 (机器翻译)

Class diagram

Code examples on this page uses the SampleException class below.

@SuppressWarnings("serial")
public class SampleException extends Exception {

    public SampleException() {
    }

    public SampleException(String message) {
        super(message);
    }

    public SampleException(String message, Throwable cause) {
        super(message, cause);
    }

    public SampleException(Throwable cause) {
        super(cause);
    }

    public SampleException(String message, Throwable cause,
                           boolean enableSuppression,
                           boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

public class Main {

    public static void main(String[] args) {
        try {
            func1();
        } catch (SampleException e) {

            final Throwable t = e;
            t.printStackTrace();

            // Result
            // ↓
            // SampleException
            //   Main.func2 ...
            //   Main.func1 ...
            //   Main.main ...
            // ...
        }
    }

    private static void func1() throws SampleException {
        func2();
    }

    private static void func2() throws SampleException {
        throw new SampleException();
    }
}

Constructors

Throwable ()

构造一个新的可抛出对象，以 null 作为其详细消息。 (机器翻译)

final Throwable t = new SampleException();
System.out.println(t); // SampleException

Throwable (String message)

使用指定详细消息构造一个新的可抛出对象。 (机器翻译)

final Throwable t = new SampleException("abcde");
System.out.println(t); // SampleException: abcde
System.out.println(t.getMessage()); // abcde

Throwable (String message, Throwable cause)

使用指定的详细消息和原因构造一个新的可抛出对象。 (机器翻译)

final Throwable cause = new SampleException("XYZ");
final Throwable t = new SampleException("abcde", cause);

System.out.println(t); // SampleException: abcde
System.out.println(t.getMessage()); // abcde

System.out.println(t.getCause()); // SampleException: XYZ
System.out.println(t.getCause().getMessage()); // XYZ

Throwable (String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace)

构造一个新的可抛出对象，带有指定详细消息、原因、启用或禁用抑制以及启用或禁用可写堆栈跟踪。 (机器翻译)

final Throwable cause = new SampleException("XYZ");
final Throwable t = new SampleException("abcde", cause, true, true);

System.out.println(t); // SampleException: abcde
System.out.println(t.getCause()); // SampleException: XYZ

t.addSuppressed(new SampleException("E1"));
t.addSuppressed(new SampleException("E2"));

// [SampleException: E1, SampleException: E2]
System.out.println(Arrays.toString(t.getSuppressed()));

System.out.println(t.getStackTrace().length > 0); // true

// enableSuppression = false
final Throwable cause = new SampleException("XYZ");
final Throwable t = new SampleException("abcde", cause, false, true);

System.out.println(t); // SampleException: abcde
System.out.println(t.getCause()); // SampleException: XYZ

t.addSuppressed(new SampleException("E1"));
t.addSuppressed(new SampleException("E2"));
System.out.println(Arrays.toString(t.getSuppressed())); // []

System.out.println(t.getStackTrace().length > 0); // true

// writableStackTrace = false
final Throwable cause = new SampleException("XYZ");
final Throwable t = new SampleException("abcde", cause, true, false);

System.out.println(t); // SampleException: abcde
System.out.println(t.getCause()); // SampleException: XYZ

t.addSuppressed(new SampleException("E1"));
t.addSuppressed(new SampleException("E2"));

// [SampleException: E1, SampleException: E2]
System.out.println(Arrays.toString(t.getSuppressed()));

System.out.println(t.getStackTrace().length); // 0

Throwable (Throwable cause)

使用指定的原因和详细消息 (cause==null ? null : cause.toString()) 构造一个新的可抛出对象（通常包含原因的类和详细消息）。 (机器翻译)

final Throwable cause = new SampleException("XYZ");
final Throwable t = new SampleException(cause);

System.out.println(t); // SampleException: SampleException: XYZ
System.out.println(t.getMessage()); // SampleException: XYZ

System.out.println(t.getCause()); // SampleException: XYZ
System.out.println(t.getCause().getMessage()); // XYZ

Methods

final void addSuppressed (Throwable exception)

将指定的异常附加到被抑制的异常中，以便传递此异常。 (机器翻译)

final Throwable t = new SampleException("abcd");
System.out.println(t); // SampleException: abcd

t.addSuppressed(new SampleException("E1"));
t.addSuppressed(new SampleException("E2"));

final var ret = t.getSuppressed();
System.out.println(Arrays.toString(ret)); // [SampleException: E1, SampleException: E2]

Throwable fillInStackTrace ()

填写执行堆栈跟踪。 (机器翻译)

public class Main {

    public static void main(String[] args) {
        try {
            func1();
        } catch (SampleException e) {
            final Throwable t = e;

            System.out.println("-- getStackTrace --");
            for (final var element : t.getStackTrace()) {
                System.out.println(element);
            }

            // Result
            // ↓
            //-- getStackTrace --
            // Main.func2 ...
            // Main.func1 ...
            // Main.main ...
            // ...

            // The stack trace is overwritten.
            final var ret = t.fillInStackTrace();
            System.out.println(ret); // SampleException

            System.out.println("-- getStackTrace --");
            for (final var element : t.getStackTrace()) {
                System.out.println(element);
            }

            // Result
            // ↓
            //-- getStackTrace --
            // Main.main ...
            // ...
        }
    }

    private static void func1() throws SampleException {
        func2();
    }

    private static void func2() throws SampleException {
        throw new SampleException();
    }
}

Throwable getCause ()

返回此可抛出事件的原因，如果原因不存在或未知，则返回 null。 (机器翻译)

final Throwable t = new SampleException();
System.out.println(t); // SampleException
System.out.println(t.getCause()); // null

final Throwable cause = new SampleException("XYZ");
final Throwable t = new SampleException(cause);

System.out.println(t); // SampleException: SampleException: XYZ

System.out.println(t.getCause()); // SampleException: XYZ
System.out.println(t.getCause().getMessage()); // XYZ

String getLocalizedMessage ()

创建此可抛出对象的本地化描述。 (机器翻译)

@SuppressWarnings("serial")
class LocalizedException extends Exception {

    private final static String MESSAGE_EN = "Exception! (EN)";
    private final static String MESSAGE_JA = "Exception! (JA)";

    LocalizedException() {
        super(MESSAGE_EN);
    }

    @Override
    public String getLocalizedMessage() {
        // It is a simple implementation.
        final var locale = Locale.getDefault();
        return switch (locale.getLanguage()) {
            case "ja" -> MESSAGE_JA;
            default -> MESSAGE_EN;
        };
    }
}

{
    System.out.println(Locale.getDefault().toLanguageTag()); // en-US

    final Throwable t = new LocalizedException();

    System.out.println(t); // LocalizedException: Exception! (EN)
    System.out.println(t.getMessage()); // Exception! (EN)
    System.out.println(t.getLocalizedMessage()); // Exception! (EN)
}

{
    Locale.setDefault(Locale.JAPAN);
    System.out.println(Locale.getDefault().toLanguageTag()); // ja-JP

    final Throwable t = new LocalizedException();

    System.out.println(t); // LocalizedException: Exception! (JA)
    System.out.println(t.getMessage()); // Exception! (EN)
    System.out.println(t.getLocalizedMessage()); // Exception! (JA)
}

String getMessage ()

返回此可抛出对象的详细消息字符串。 (机器翻译)

final Throwable t = new SampleException("abcd");

System.out.println(t); // SampleException: abcd
System.out.println(t.getMessage()); // abcd

StackTraceElement[] getStackTrace ()

提供对 printStackTrace() 打印的堆栈跟踪信息的编程访问。 (机器翻译)

public class Main {

    public static void main(String[] args) {
        try {
            func1();
        } catch (SampleException e) {
            final Throwable t = e;

            System.out.println("-- getStackTrace --");
            for (final var element : t.getStackTrace()) {
                System.out.println(element);
            }

            // Result
            // ↓
            //-- getStackTrace --
            // Main.func2 ...
            // Main.func1 ...
            // Main.main ...
            // ...
        }
    }

    private static void func1() throws SampleException {
        func2();
    }

    private static void func2() throws SampleException {
        throw new SampleException();
    }
}

final Throwable[] getSuppressed ()

返回一个数组，其中包含所有被抑制的异常（通常通过 try-with-resources 语句），以便传递此异常。 (机器翻译)

final Throwable t = new SampleException("abcd");
System.out.println(t); // SampleException: abcd

t.addSuppressed(new SampleException("E1"));
t.addSuppressed(new SampleException("E2"));

final var ret = t.getSuppressed();
System.out.println(Arrays.toString(ret)); // [SampleException: E1, SampleException: E2]

Throwable initCause (Throwable cause)

将此可抛出事件的原因初始化为指定值。 (机器翻译)

final Throwable t = new SampleException();

System.out.println(t); // SampleException
System.out.println(t.getCause()); // null

final Throwable cause = new SampleException("XYZ");

System.out.println(t.initCause(cause)); // SampleException

System.out.println(t.getCause()); // SampleException: XYZ

void printStackTrace ()

将此可抛出对象及其回溯打印到标准错误流。 (机器翻译)

public class Main {

    public static void main(String[] args) {
        try {
            func1();
        } catch (SampleException e) {

            final Throwable t = e;
            t.printStackTrace();

            // Result
            // ↓
            // SampleException
            //   Main.func2 ...
            //   Main.func1 ...
            //   Main.main ...
            // ...
        }
    }

    private static void func1() throws SampleException {
        func2();
    }

    private static void func2() throws SampleException {
        throw new SampleException();
    }
}

void printStackTrace (PrintStream s)

将此可抛出对象及其回溯打印至指定的打印流。 (机器翻译)

public class Main {

    public static void main(String[] args) throws IOException {

        try {
            func1();
        } catch (SampleException e) {
            final Throwable t = e;

            final var path = Path.of("R:", "java-work", "aaa.txt");
            try (final var s = new PrintStream(Files.newOutputStream(path))) {
                t.printStackTrace(s);
            }

            System.out.println("-- readString --");
            System.out.println(Files.readString(path));

            // Result
            // ↓
            //-- readString --
            // SampleException
            //   Main.func2 ...
            //   Main.func1 ...
            //   Main.main ...
            // ...
        }
    }

    private static void func1() throws SampleException {
        func2();
    }

    private static void func2() throws SampleException {
        throw new SampleException();
    }
}

void printStackTrace (PrintWriter s)

将此可抛出对象及其回溯打印到指定的打印编写器。 (机器翻译)

public class Main {

    public static void main(String[] args) throws IOException {
        try {
            func1();
        } catch (SampleException e) {
            final Throwable t = e;

            final var stringWriter = new StringWriter();
            try (final var printWriter = new PrintWriter(stringWriter)) {
                t.printStackTrace(printWriter);
            }

            System.out.println("-- StringWriter --");
            System.out.println(stringWriter);

            // Result
            // ↓
            //-- StringWriter --
            // SampleException
            //   Main.func2 ...
            //   Main.func1 ...
            //   Main.main ...
            // ...
        }
    }

    private static void func1() throws SampleException {
        func2();
    }

    private static void func2() throws SampleException {
        throw new SampleException();
    }
}

void setStackTrace (StackTraceElement[] stackTrace)

设置将由 getStackTrace() 返回并由 printStackTrace() 和相关方法打印的堆栈跟踪元素。 (机器翻译)

final Throwable t = new SampleException();

final var elements = List.of(
        new StackTraceElement("ClassA", "methodB", "FileC.java", 123),
        new StackTraceElement("ClassX", "methodY", "FileZ.java", 456)
);

t.setStackTrace(elements.toArray(new StackTraceElement[0]));

t.printStackTrace();

// Result
// ↓
//SampleException
//  at ClassA.methodB(FileC.java:123)
//  at ClassX.methodY(FileZ.java:456)

String toString ()

返回此可抛出对象的简短描述。 (机器翻译)

final Throwable t = new SampleException("abcde");

final var str = t.toString();
System.out.println(str); // SampleException: abcde

API 示例
- Exception
  - ExecutionException
  - IOException
    - FileSystemException
- RuntimeException
  - PatternSyntaxException

Java : Throwable 示例

简介

Constructors

Throwable ()

Throwable (String message)

Throwable (String message, Throwable cause)

Throwable (String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace)

Throwable (Throwable cause)

Methods

final void addSuppressed (Throwable exception)

Throwable fillInStackTrace ()

Throwable getCause ()

String getLocalizedMessage ()

String getMessage ()

StackTraceElement[] getStackTrace ()

final Throwable[] getSuppressed ()

Throwable initCause (Throwable cause)

void printStackTrace ()

void printStackTrace (PrintStream s)

void printStackTrace (PrintWriter s)

void setStackTrace (StackTraceElement[] stackTrace)

String toString ()

相关文章