Java : IllegalStateException with Examples

IllegalStateException (Java SE 21 & JDK 21) with Examples.
You will find code examples on most IllegalStateException methods.

Summary

Signals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.

Class diagram

final var queue = new ArrayBlockingQueue<String>(3);
System.out.println(queue.remainingCapacity()); // 3

queue.add("aaa");
queue.add("bbb");
queue.add("ccc");

System.out.println(queue); // [aaa, bbb, ccc]
System.out.println(queue.remainingCapacity()); // 0

try {
    queue.add("ddd");
} catch (IllegalStateException e) {
    System.out.println(e);
}

// Result
// ↓
//java.lang.IllegalStateException: Queue full

class Sample implements Closeable {
    private boolean closed;

    @Override
    public void close() {
        closed = true;
    }

    public String read() {
        if (closed) {
            throw new IllegalStateException("Closed!");
        }

        return "abcd";
    }
}

final var sample = new Sample();
System.out.println(sample.read()); // abcd

sample.close();

try {
    final var ret = sample.read();
} catch (IllegalStateException e) {
    System.out.println(e);
}

// Result
// ↓
//java.lang.IllegalStateException: Closed!

Constructors

IllegalStateException ()

Constructs an IllegalStateException with no detail message.

final var e = new IllegalStateException();
System.out.println(e); // java.lang.IllegalStateException

IllegalStateException (String s)

Constructs an IllegalStateException with the specified detail message.

final var e = new IllegalStateException("abcde");
System.out.println(e); // java.lang.IllegalStateException: abcde
System.out.println(e.getMessage()); // abcde

IllegalStateException (String message, Throwable cause)

Constructs a new exception with the specified detail message and cause.

final var cause = new IllegalStateException("XYZ");
final var e = new IllegalStateException("abcde", cause);

System.out.println(e); // java.lang.IllegalStateException: abcde
System.out.println(e.getMessage()); // abcde

System.out.println(e.getCause()); // java.lang.IllegalStateException: XYZ
System.out.println(e.getCause().getMessage()); // XYZ

IllegalStateException (Throwable cause)

Constructs a new exception with the specified cause and a detail message of (cause==null ? null : cause.toString()) (which typically contains the class and detail message of cause).

final var cause = new IllegalStateException("XYZ");
final var e = new IllegalStateException(cause);

System.out.println(e); // java.lang.IllegalStateException: java.lang.IllegalStateException: XYZ
System.out.println(e.getMessage()); // java.lang.IllegalStateException: XYZ

System.out.println(e.getCause()); // java.lang.IllegalStateException: XYZ
System.out.println(e.getCause().getMessage()); // XYZ

Methods declared in Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Please see the link below.

Throwable with Examples

API Examples

Java : IllegalStateException with Examples

Summary

Constructors

IllegalStateException ()

IllegalStateException (String s)

IllegalStateException (String message, Throwable cause)

IllegalStateException (Throwable cause)

Methods declared in Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

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