Date Formatter

Is the ParseException happens?

SimpleDateFormat df = new SimpleDateFormat("dd-MM-yyyy");
Date date = null;
try {
//1
date = df.parse("12-34-2007");
} catch (ParseException e) {
System.out.println("Wrong date");
}
System.out.println(date.toString());

Actually not. To prevent this add to //1
df.setLenient(false);

Letient parameter is true by default that's why to match format strictly need
setting parameter to false

Windows fonts

sudo apt-get install msttcorefonts

Converting image

As our Designer was fired because of crisis - I had to change images size. So imagemagic is excelent for this use.

mogrify -gravity Center -crop 30X22+0+0 *.png
mogrify -format png *.jpg
mogrify -resize 30x22+0+0 *.*
mogrify -resize 120% *.*

identify -format "%wx%h \n" *.*


Hibernate Custom Type

Database has for example wrong state and can't save 1 or 0, 'Y' or 'N', 'YES' or 'NO'
So you need to save state as 1 and 2. Seems that database need refactoring... yes you are right but if you can't? Here is decision - custom type

package com.types;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;

public class OneTwoBooleanType implements UserType{

private final static int DB_TRUE = 1;
private final static int DB_FALSE = 2;

public Object assemble(Serializable cached, Object owner) throws HibernateException {
return cached;
}

public Object deepCopy(Object value) throws HibernateException {
return value;
}

public Serializable disassemble(Object value) throws HibernateException {
return (Serializable) value;
}

public boolean equals(Object x, Object y) throws HibernateException {
if(x==null){
return false;
}
return ((Boolean)x).equals(y);
}

public int hashCode(Object x) throws HibernateException {
return x.hashCode();
}

public boolean isMutable() {
return false;
}

public Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws HibernateException, SQLException {
Number val = (Number) rs.getObject(names[0]);
if(val==null){
return false;
}
return val.intValue() == DB_TRUE ? true : false;
}

public void nullSafeSet(PreparedStatement st, Object value, int index) throws HibernateException, SQLException {
int dbValue;
if(value==null){
dbValue = DB_FALSE;
} else {
dbValue = (Boolean) value ? DB_TRUE : DB_FALSE;
}
st.setInt(index, dbValue);
}

public Object replace(Object original, Object target, Object owner) throws HibernateException {
return original;
}

public Class returnedClass() {
return Boolean.class;
}

public int[] sqlTypes() {
return new int[]{Types.SMALLINT};
}

}

And It's usage

@Column(name="INTERNAL_STATUS_ID")
@Type(type="com.types.OneTwoBooleanType")
private boolean isVisible;


Substract queries

If you need to check differences between tables use this query:

select * from t1
minus
select * from t2


Java version number


import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class ClassVersionChecker {
public static void main(String[] args) throws IOException {
for (int i = 0; i < args.length; i++)
checkClassVersion(args[i]);
}

private static void checkClassVersion(String filename) throws IOException {
DataInputStream in = new DataInputStream(new FileInputStream(filename));

int magic = in.readInt();
if (magic != 0xcafebabe) {
System.out.println(filename + " is not a valid class!");
}
int minor = in.readUnsignedShort();
int major = in.readUnsignedShort();
System.out.println(filename + ": " + major + " . " + minor);
in.close();
}
}


1.Compile

javac ClassVersionChecker.java

2.Execute in unix console

find . -name *.class|xargs java -cp /c/tmp ClassVersionChecker|grep 50

where last number is class version

major minor Java platform version
45 3 1.0
45 3 1.1
46 0 1.2
47 0 1.3
48 0 1.4
49 0 1.5
50 0 1.6


Statistical SQL query

For example you need to count how many companies in which source system:

select count(*), source_system_id from company group by rollup(source_system_id)