如何在Java中使用正则表达式或子字符串从字符串中提取文本？

Question

I have this Runnable

Runnable serverChecksRunnable = new Runnable()
    {
        @Override
        public void run()
        {
            if (connectedSuccess == true)
            {
                    checkServer = Get(iptouse + "uploadstatus");

            }

            Handler h=new Handler(Looper.getMainLooper());
            h.post(new Runnable()
            {
                @Override
                public void run()
                {
                    if (connectedSuccess)
                    {
                        if (checkServer != null)
                        {
                            String a = null;
                            try
                            {
                                a = new String(checkServer, "UTF-8");
                                textforthespeacch = a;
                                {
                                    String varr = textforthespeacch.substring(17,3);
                                    String varr1 = textforthespeacch.substring(0, 16);
                                    String varr2 = textforthespeacch.substring(21);
                                    textforthespeacch = varr1;
                                    status1.setText("Upload completed" + " " + varr + "%");
                                    timerValue.setText("00:00:" + varr2);
                                    numberofuploadedfilescounter += 1;
                                    uploadedfilescount.setText(("Uploaded Files: " + numberofuploadedfilescounter));
                                    MainActivity.this.initTTS();
                                }
                                if (textforthespeacch.contains("uploading"))
                                {
                                    String[] split = textforthespeacch.split(" ");
                                    textforthespeacch = split[0];
                                    status1.setText("Uploading" + " " + split[1] + "%");
                                    servercheckCounter += 1;
                                    if (servercheckCounter == 1)
                                    {
                                        MainActivity.this.initTTS();
                                    }
                                }
                            } catch (UnsupportedEncodingException e)
                            {
                                e.printStackTrace();
                            }
                        }
                    }

                }
            });

            customHandler.postDelayed(serverChecksRunnable,1000);
        }
    };

The var textforthespeacch is string and get text from a web server. Then i check when it contains a part of a text assign the text parts to three vars:

if (textforthespeacch.contains("upload completed"))
                                {
                                    String varr = textforthespeacch.substring(17,3);
                                    String varr1 = textforthespeacch.substring(0, 16);
                                    String varr2 = textforthespeacch.substring(21);

The problem is that the program crash on the first substring(17,3)

The text in the textforspeech is: "upload completed 100 0" The number 100 present percentages and will be all the time 100. And the number 0 present seconds it can be changed sometimes 0 sometimes 1 and sometimes 34.5

In varr I need to put the 100 as string "100" In varr1 "upload completed" in varr2 "0"

varr2 might be changed to can be "0" or "1" or "45.5" the others varr and varr1 never change the text "100" and "upload completed" never change.

This is the exception message in the logcat i'm getting:

09-15 18:45:45.435    5583-5583/com.test.webservertest E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.test.webservertest, PID: 5583
    java.lang.StringIndexOutOfBoundsException: length=22; regionStart=17; regionLength=-15
            at java.lang.String.startEndAndLength(String.java:504)
            at java.lang.String.substring(String.java:1333)
            at com.adilipman.webservertest.MainActivity$2$1.run(MainActivity.java:235)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5274)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:909)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:704)

Answer 1

With this line

String varr = textforthespeacch.substring(17,2);

The first value in a substring call must be less than the second. That is why you get regionLength=-15 .

Answer 2

Here is the syntax for the substring() method:

public String substring(int beginIndex)

or

public String substring(int beginIndex, int endIndex)

where

beginIndex -- the begin index, inclusive.

endIndex -- the end index, exclusive.

How can the endIndex in: String varr = textforthespeacch.substring(17,3); be less than the beginIndex .

I think it should be the other way round.