Java String Concatenation

Question

I have a issue with my java code. i asked the same question yesterday. I got answer but sorry it was my fault. My question is not clear.

I have code looks like this:

Answer 1

Try this:

StringBuilder sb = new StringBuilder();
for(i = 0; i < geo.getTargets().length ; i++ ){
  if(geo.getTargets(i).getTargetType().equalsIgnoreCase("ProximityTarget")){
    final ProximityTarget prox = (ProximityTarget)geo.getTargets(i);
    float longitude = prox.getGeoPoint().getLatitudeInMicroDegrees()); 
    float lat = prox.getGeoPoint().getLongitudeInMicroDegrees());
    float radius = prox.getRadiusDistanceUnits();

    if (sb.isEmpty()) {
        sb.append("circle:" + longitude + ":" + lat + ":" + radius);
    else {
        sb.append(" | circle:" + longitude + ":" + lat + ":" + radius);
    }
  }
}
String result = sb.toString();

Answer 2

moreover, if it is possible to estimate the size of the concatenated string, you could use StringBuffer(int capacity)/StringBuilder(int capacity) to avoid resizing

Answer 3

This is the basic way of doing what you asked for with String + operator.

  String result = "";
    for(i = 0; i < geo.getTargets().length ; i++ ){
      if(geo.getTargets(i).getTargetType().equalsIgnoreCase("ProximityTarget")){
        final ProximityTarget prox = (ProximityTarget)geo.getTargets(i);
        float longitude = prox.getGeoPoint().getLatitudeInMicroDegrees()); 
        float lat = prox.getGeoPoint().getLongitudeInMicroDegrees());
        float radius = prox.getRadiusDistanceUnits();

        if (!result.isEmpty()) {
            result += "|";
        }

        result += ("circle:" + longitude + ":" + lat + ":" + radius);
      }
    }

    return result;

Answer 4

public String asString(ProximityTarget target) {
    StringBuilder sb = new StringBuilder("circle:");
    sb.append(target.getGeoPoint().getLatitudeInMicroDegrees()).append(":");
    sb.append(target.getGeoPoint().getLongitudeInMicroDegrees()).append(":");
    sb.append(target.getRadiusDistanceUnits());
    return sb.toString();
}

public void someMethod() {
    //...
    StringBuilder sb = new StringBuilder();
    for(i = 0; i < geo.getTargets().length ; i++ )
    {
        if(geo.getTargets(i).getTargetType().equalsIgnoreCase("ProximityTarget"))
        {
            final ProximityTarget prox = (ProximityTarget)geo.getTargets(i);

            if (!sb.isEmpty())
                sb.append("|");

            sb.append(asString(prox));
        }
    }
    String formattedString = sb.toString();

    //...
}

Answer 5

The most basic way of doing Java string concatenation is to use the + operator. Set up:

String value = string1 + string2 + string3;

There are other ways to do it, but this simple case should handle your needs. For further information, look into StringBuilder.

Answer 6

Depends on the kind of environment you're on. If you don't need thread safety, use stringbuilder. The stringbuffer class provides the necessary synchronisation when needed.