Пример

public void print( String str ){
System.out.println("String: " + str ); //$NON-NLS-1$
}

public void print( Object obj ){
System.out.println("Object: " + obj ); //$NON-NLS-1$
}


public static void main(String[] args){
MultipleOverloadedMethods_Example example = new MultipleOverloadedMethods_Example();
example.print( "Hello World!" ); //$NON-NLS-1$
example.print( (Object)"Hello World!" ); //$NON-NLS-1$
}

Исправление
Сделайте имена методов различными.

public void printString( String str ){
System.out.println("String: " + str ); //$NON-NLS-1$
}

public void printObject( Object obj ){
System.out.println("Object: " + obj ); //$NON-NLS-1$
}


public static void main(String[] args){
MultipleOverloadedMethods_Solution example = new MultipleOverloadedMethods_Solution();
example.printString( "Hello World!" ); //$NON-NLS-1$
example.printObject( "Hello World!" ); //$NON-NLS-1$
}