报春使者是什么鸟:一个JAVA的问题，请高手指点一下。

public PasswdLevel4()
{
inuser = new String[22];
totno = 0;
countConn = null;
countData = null;
inURL = null;
txtlogin = new TextField();
label1 = new Label();
label2 = new Label();
label3 = new Label();
txtpass = new TextField();
lblstatus = new Label();
ButOk = new Button();
ButReset = new Button();
lbltitle = new Label();
}
void ButOk_ActionPerformed(ActionEvent actionevent)
{
boolean flag = false;
for(int i = 1; i <= totno / 2; i++)
if(txtlogin.getText().trim().toUpperCase().intern() == inuser[2 * (i - 1) + 2].trim().toUpperCase().intern() && txtpass.getText().trim().toUpperCase().intern() == inuser[2 * (i - 1) + 3].trim().toUpperCase().intern())
{
lblstatus.setText("Login Success, Loading..");
flag = true;
String s = inuser[1].trim().intern();
String s1 = getParameter("targetframe");
if(s1 == null)
s1 = "_self";
try
{
finalurl = new URL(getCodeBase(), s);
}
catch(MalformedURLException _ex)
{
lblstatus.setText("Bad URL");
}
getAppletContext().showDocument(finalurl, s1);
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这是一个JAVA程序的片断，请问
for(int i = 1; i <= totno / 2; i++)
if(txtlogin.getText().trim().toUpperCase().intern() == inuser[2 * (i - 1) + 2].trim().toUpperCase().intern() && txtpass.getText().trim().toUpperCase().intern() == inuser[2 * (i - 1) + 3].trim().toUpperCase().intern())这个语句是什么意思？如何满足他？