Eclipse自动生成toString（）方法

Question

As par as I know concatinate String using + sign is not a good practice when you have large number of String. But when I check on eclipse generated toString() method (Write click on source file -> Source -> Generate toString() ) it has the same.

public class Temp
 {
      private String tempName;
      private String tempValue;

      // here getters and setters

  /* (non-Javadoc)
         * @see java.lang.Object#toString()
  */
@Override
public String toString() {
    return "Temp [tempName=" + tempName + ", tempValue=" + tempValue + "]";
}

}

Is there any place to configure like my expected toString() method like bellow in eclipse or Why the eclipse doesn't consider that.

   public String expectedToString(){
    StringBuffer sb = new StringBuffer();
    sb.append("Temp [tempName=").append(tempName).append(",").append(" tempValue=").append(tempValue).append("]");
    return sb.toString();
}

I'm going to use auto generated toString() method to log my object values.

Kindly advice me.

Answer 1

No need to change anything, it's compact and easily readable, javac will use StringBuilder for actual concatination, if you decompile your Temp.class you will see

public String toString() {
   return (new StringBuilder("Temp [tempName=")).append(tempName).append(", tempValue=").append(tempValue).append("]").toString();
}

But in other situations, like

    String[] a = { "1", "2", "3" };
    String str = "";
    for (String s : a) {
        str += s; 
    }

+ or += is a real performance killer, see decompiled code

String str = "";
for(int i = 0; i < j; i++) {
    String s = args1[i];
    str = (new StringBuilder(String.valueOf(str))).append(s).toString();
}

on each iteration a new StringBuilder is created and then converted to String. Here you should use StringBuilder explictily

    StringBuilder sb = new StringBuilder();
    for (String s : a) {
        sb.append(s); 
    }
    String str = sb.toString();