Question

I hava again run it interesting problem, I need to dynamically build SQL query which contatins the IN condition. So I have list of String and I need to insert them to my StringBuilder separated by the coma.

So my first idea was to employ some boolean value to determine if I should insert the coma or not.

builder.append("TABLE.METACODES in (");
boolean isFirst = true;
for(String metaCode : cto.getEntityMetaCodes()) {
    if(isFirst) {
        isFirst = false;
        builder.append("'" + metaCode + "'");
    } else {
         builder.append(", '" + metaCode + "'");
    }
 }
 builder.append(")");

Can yout think of any better solution?

Answer 1

Without using an external library, I would do something like:

builder.append("TABLE.METACODES in (");
EntityMetaCodes emc = cto.getEntityMetaCodes();
builder.append("'" + emc.remove(0) + "'"); // assuming it's an ArrayList, remove(0) takes out the
                               // first element and moves everything else to the left
for(String metaCode : emc) {
    builder.append(", '" + metaCode + "'");
}
builder.append(")");