ConvertBasicValue Tutorial

This tutorial provides an overview of the ConvertBasicValue class, which is part of the lightweight-component/aj-util library. ConvertBasicValue offers a collection of utility methods for converting objects to basic Java types. This guide will cover the purpose of each method and provide usage examples.

Introduction

The ConvertBasicValue class provides methods for safely converting objects to various basic Java types like String, boolean, int, long, float, double, Date, and BigDecimal. These methods handle null values and attempt to parse string representations where appropriate, providing a more robust alternative to direct casting.

Methods

1. basicCast(Object value, Class<T> clz)

Safely casts an object to a specified class type. This method leverages basicConvert to perform the initial conversion and then casts the result to the desired type.

• Parameters:
  • value: The object to convert.
  • clz: The target class type.
• Returns: The converted object of type T.

Example:

Integer intValue = ConvertBasicValue.basicCast("123", Integer.class);
// intValue will be 123

2. basicConvert(Object value, Class<?> clz)

Converts an object to a specified class type. This method handles null values and performs type-specific conversions.

• Parameters:
  • value: The object to convert.
  • clz: The target class type.
• Returns: The converted object, or null if the input value is null.

This method contains the core logic for different type conversions. Let's look at some of the specific conversions it handles:

• String: Converts the object to a string using value.toString().
• boolean/Boolean: Converts the object to a boolean using the toBoolean() method (explained below).
• int/Integer: Converts the object to an integer using the object2int() method (explained below).
• long/Long: Converts the object to a long using the object2long() method (explained below).
• float/Float: Converts the object to a float using the object2float() method.
• double/Double: Converts the object to a double using the object2double() method.
• Date: Converts the object to a Date using the DateHelper.object2Date() method.
• BigDecimal: Converts the object to a BigDecimal if the value is a String or Number.
• Array: Converts the object to an array using the toArray() method.
• Enum: Converts the object to an enum.

3. toBoolean(Object value)

Converts an object to a boolean. This method handles various input types, including strings, numbers, and booleans.

• Parameters:
  • value: The object to convert.
• Returns: The boolean value of the object.

Examples:

assertTrue(ConvertBasicValue.toBoolean(true));
assertTrue(ConvertBasicValue.toBoolean("true"));
assertTrue(ConvertBasicValue.toBoolean("1"));
assertFalse(ConvertBasicValue.toBoolean("false"));
assertFalse(ConvertBasicValue.toBoolean(0));

4. object2int(Object value)

Converts an object to an integer. This method handles null values and attempts to parse string representations.

• Parameters:
  • value: The object to convert.
• Returns: The integer value of the object, or 0 if the input value is null.
• Throws: IllegalArgumentException if the object cannot be converted to an integer.

Examples:

assertEquals(0, ConvertBasicValue.object2int(null));
assertEquals(123, ConvertBasicValue.object2int("123"));
assertEquals(-456, ConvertBasicValue.object2int("-456"));

5. object2long(Object value)

Converts an object to a long. This method handles null values and attempts to parse string representations.

• Parameters:
  • value: The object to convert.
• Returns: The long value of the object, or 0L if the input value is null.
• Throws: IllegalArgumentException if the object cannot be converted to a long.

Examples:

assertEquals(0L, ConvertBasicValue.object2long(null));
assertEquals(123L, ConvertBasicValue.object2long("123"));
assertEquals(-456L, ConvertBasicValue.object2long("-456"));

6. object2double(Object value)

Converts an object to a double. This method handles null values and attempts to parse string representations.

• Parameters:
  • value: The object to convert.
• Returns: The double value of the object, or 0.0 if the input value is null.

Examples:

assertEquals(0.0, ConvertBasicValue.object2double(null), 0.0001);
assertEquals(3.14, ConvertBasicValue.object2double("3.14"), 0.0001);

Unit Test Examples

Here are some examples from the unit tests:

import org.junit.jupiter.api.Test;
import static com.ajaxjs.util.ConvertBasicValue.*;
import static org.junit.jupiter.api.Assertions.*;

public class TestConvertBasicValue {
    @Test
    public void testToBoolean() {
        assertTrue(toBoolean(true));
        assertTrue(toBoolean("true"));
        assertTrue(toBoolean("True"));

        assertFalse(toBoolean("fAlse"));
        assertFalse(toBoolean("null"));

        assertTrue(toBoolean("on"));
        assertTrue(toBoolean("yes"));
        assertTrue(toBoolean(1));
        assertTrue(toBoolean("1"));
    }

    @Test
    public void testObject2Int() {
        assertEquals(0, object2int(null));
        assertEquals(100, object2int(100));
        assertEquals(123, object2int("123"));
    }

    @Test
    public void testObject2Long() {
        assertEquals(0L, object2long(null));
        assertEquals(100L, object2long(100L));
        assertEquals(123L, object2long("123"));
    }

    @Test
    public void testObject2Double() {
        assertEquals(0.0, object2double(null), 0.0001);
        assertEquals(3.14, object2double(3.14), 0.0001);
    }
}

Conclusion

The ConvertBasicValue class provides a useful set of utilities for safely converting objects to basic Java types. By using these methods, you can simplify your code and handle potential null values and parsing errors more gracefully. Remember to consult the library's Javadoc for the most up-to-date information and additional methods.