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Java Reflection - Field.getLong() Examples

[Last Updated: Nov 8, 2025]

Java Reflection Java Java API

Class:

java.lang.reflect.Field

Method:

public long getLong(Object obj)
             throws IllegalArgumentException,
                    IllegalAccessException

Gets the value of a static or instance field of type long or of another primitive type convertible to type long via a widening conversion.

Examples

package com.logicbig.example.field;

import java.lang.reflect.Field;

public class GetLongExample {
    private long l = 20;

    public static void main(String... args) throws NoSuchFieldException, IllegalAccessException {
        Field f = GetLongExample.class.getDeclaredField("l");
        long value = f.getLong(new GetLongExample());
        System.out.println(value);
    }
}

Output

Widening conversion from double to long:

package com.logicbig.example.field;

import java.lang.reflect.Field;

public class GetLongExample2 {
    private int i = 100;

    public static void main(String... args) throws NoSuchFieldException, IllegalAccessException {
        Field field = GetLongExample2.class.getDeclaredField("i");
        long v = field.getLong(new GetLongExample2());
        System.out.println(v);
    }
}

Output

Static field example:

package com.logicbig.example.field;

import java.lang.reflect.Field;

public class GetLongExample3 {
    private static long l = 100;

    public static void main(String... args) throws NoSuchFieldException, IllegalAccessException {
        Field f = GetLongExample3.class.getDeclaredField("l");
        long aLong = f.getLong(null);
        System.out.println(aLong);
    }
}

Output

See Also