String string = ""; 与String string = new String();的区别

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package po;import org.apache.commons.httpclient.UsernamePasswordCredentials;import org.omg.CORBA.PUBLIC_MEMBER;public class Text {public static void main(String[] args) {String s = "";String ss = new String();if(s == ss) { //falseSystem.out.println("111");} if(s == "") { //tureSystem.out.println("222");}if(ss == "") { //falseSystem.out.println("333");}if(ss.equals("")) { //trueSystem.out.println("444");}//当一个项目中为了解决get提交乱码问题 使用String对象转码时就会出现问题String string =  new String(request.getParameter("username").getBytes("ISO-8859-1"),"GBK");//比如你之前是这样判断的String username = "";if(username == "") {System.out.println("这句话会执行!");}//但是你new String()的时候String username = new String(request.getParameter("username").getBytes("ISO-8859-1"),"GBK");if(username == "") {System.out.println("这句话不会执行!");}if(username.equals("")) {System.out.println("这句话会执行!");}}}

故 最后给出意见，不管是String s = ""; 还是String s = new String();判断是否为空都一律用if(s.equals(""))判断

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