April 16, 2018

org.hibernate.AnnotationException: No identifier specified for entity

When I was working with hibernate project. I got this exception. Actually, the issue was because of missing @Id from one of my entity class. @Id is used on the primary key field in the entity class. The field is a primary key in your database table.

If you do not have any primary key in your database table then you can use rowId as the primary key for your entity class.

@Column(name = "ROWID", insertable = false, updatable = false)
private String rowId;

February 4, 2018

error: possible loss of precision using Math.pow in java

Problem : I compiled below code and got possible loss of precision error.
int a = Math.pow(3, 5);

Solution : According to the java documentation, Math.pow() expects two doubles, and returns a double. When you pass two int values to this method, it converts an int to double. But when we assign the value to an int, it gives, possible loss of precision error while compiling the code. So you can cast method to an int or assign the returning value to double to resolve the error.

int a = (int)Math.pow (3,5);
double a = Math.pow (3,5);


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