java的BigDecimal比較大小

//前提為a、b均不能為null
if(a.compareTo(b) == -1){
    System.out.println("a小於b");
}
 
if(a.compareTo(b) == 0){
    System.out.println("a等於b");
}
 
if(a.compareTo(b) == 1){
    System.out.println("a大於b");
}
 
if(a.compareTo(b) > -1){
    System.out.println("a大於等於b");
}
 
if(a.compareTo(b) < 1){
    System.out.println("a小於等於b");
}