JPA: java.lang.StackOverflowError on adding toString method in entity classes

Entity Class Teacher have toString() problem:

@Entity
public class Teacher {

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Long id;    

private String name;

@OneToMany(mappedBy="teacher", cascade={CascadeType.PERSIST})
private Set<Student> students = new HashSet<Student>(); 

public Teacher() {}
public Teacher(String name) {
    this.name = name;
}

public Set<Student> getStudents() {
    return students;
}       
public void addStudent(Student student) {
    students.add(student);
    student.setTeacher(this);
}
@Override
public String toString() {
    return "Teacher[id=" + id + ", name=" + name
            + "]";
}

}

login mysql in command window

 C:\MYSQL\bin\ to your PATH

mysql -u user_name -p  then press_enter_key

then type password

i.e.

line-1 : mysql -u root -p

line-2 : admin

1) show databases;

2) use (your preferred database);

3) show tables;

4) select * from (preferred table);

Groovy Setup Eclipse

https://github.com/groovy/groovy-eclipse/wiki


add software ->  select groovy eclipse and compilers
http://dist.springsource.org/snapshot/GRECLIPSE/e4.7

Gradle Setup - Eclipse

Eclipse - Install from Market place - buildship plugin

implementing interfaces in groovy

​interface X { 
void f(); 
void g(int n);
void h(String s, int n);
}

x = {Object[] args -> println "method called with $args"} as X 

x.f() 
x.g(5) 
x.h("a string",2)​



-----------------------------

interface X { 
void f();
void g(int n);
void h(String s, int n);
} 

x = [ f: {println "f is called"},
g: {int i-> println "g is called with param ${i}"},
h: {Object[] args -> println "h is called with ${args}"} ] as X

x.f()
x.g(5)
x.h("a string",2)​

Groovy Master - http://mrhaki.blogspot.in

Groovy Optional Return

def simple() {
    "Hello world"
}
assert 'Hello world' == simple()
 
 
def doIt(b) {
    if (b) {
        "You are true"
    } else {
        "You are false"
    }
}
assert 'You are true' == doIt(true)
assert 'You are false' == doIt(false)
 
 
def tryIt(file) {
    try {
        new File(file).text
    } catch (e) {
        "Received exception: ${e.message}"
    } finally {
        println 'Finally is executed but nothing is returned.'
        'Finally reached'
    }
}
assert 'Received exception: invalidfilename (The system cannot find the file specified)'  == tryIt('invalidfilename')
// Create new file with the name test.
def newFile = new FileWriter('test').withWriter { it.write('file contents') }
assert 'file contents' == tryIt('test')