Resolved error code: IllegalArgumentException (Illegal parameter exception): When the parameters passed to the method do not meet expectations, such as passing in invalid parameters or null values, it is easy to cause this exception

Resolved error code: IllegalArgumentException (Illegal parameter exception): When the parameters passed to the method do not meet expectations, such as passing in invalid parameters or null values, it is easy to cause this exception

Error Code Resolved: IllegalArgumentException (Illegal Argument Exception)

Project scenario:

Let's assume that in an image processing application, the user has the option to rotate an image. The app allows the user to enter a rotation angle and see a preview of the image during the rotation.

Problem Description:

In the process of image rotation, when the user enters an invalid angle value (such as out of range, non-numeric type, etc.), the application throws an IllegalArgumentException, which causes the image to fail to rotate correctly.

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Cause Analysis:

IllegalArgumentException is caused by an argument passed to a method that does not meet expectations. In our project, the image rotation method may check the legality of the angle value, but it does not correctly handle the case where the user enters an invalid angle, resulting in an exception being thrown.

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solution:

In order to solve this problem, we need to add parameter checks in the image rotation method and validate the input angle value. The specific solution is as follows:

public Image rotateImage(Image originalImage, double angle) {
    
    
    if (angle < 0 || angle > 360) {
    
    
        throw new IllegalArgumentException("无效的角度值。角度必须在0到360之间。");
    }

    // 进行图像旋转操作的代码
    // ...
}

Through the above code, we have added a parameter check to the image rotation method. When the input angle value is not within the legal range, a custom IllegalArgumentException is thrown and the user is prompted to enter a valid angle value.

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How to avoid:

In order to avoid encountering IllegalArgumentException in similar situations, we can take the following measures:

1. Validity checks and validations are always performed for user input parameters. Make sure that the values ​​entered are within the expected range and type.
2. Use assert (assert) statements or conditional judgments to discover parameter problems in a timely manner during the development phase. For example, in the above code, we can use the assert statement to check whether the angle value is within the legal range.
3. Explicitly state the expected ranges and limits of parameters in the method's doc comments so other developers can use the method correctly.

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Summarize:

In this article, we have addressed the issue of IllegalArgumentException in image processing applications. By adding appropriate parameter checking and validation, we ensure that the angle value entered by the user is within the legal range, thus effectively avoiding the occurrence of exceptions. In the development process, reasonable handling of parameters is an important part of ensuring the stability of the application, which is what we need to pay special attention to during development. Through continuous optimization and improvement, we can further improve the quality and user experience of the application.

Statement of originality:

This article is original~