一道简单的JAVA题啊,麻烦帮忙做下!!

public class Complex {
private float realPart ;
private float imagPart ;
public Complex(float realPart ,float imagPart){
this.realPart = realPart ;
this.imagPart = imagPart ;
}
public Complex(){}
/**
* 加减的方法
* @param c1
* @param c2
* @return
*/
public String addValue (Complex c1,Complex c2){
String value = "" ;
if(c1!=null && c2 !=null){
float tempReal = c1.getRealPart()+c2.getRealPart();
float tempImag = c1.getImagPart()+c2.getImagPart() ;
value = String.valueOf(tempReal)+String.valueOf(tempImag)+"i";
}

return value ;
}

//setter and getter method
public float getRealPart() {
return realPart;
}

public void setRealPart(float realPart) {
this.realPart = realPart;
}

public float getImagPart() {
return imagPart;
}

public void setImagPart(float imagPart) {
this.imagPart = imagPart;
}
}