How to increment alphanumeric number in android? [

问题:

I'm new to android coding practice

ABB20180001 Suppose this as my first id, and i wish to auto-increment this by 1 using shared preferences and use as employee id. like ABB20180002, ABB20180003, ABB20180004 etc.

回答1:

You can't increment alphanumeric values directly. if want to do so you need to write some lines of code for it

here is activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <TextView
        android:id="@+id/txt_autoincreament"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="click"
        android:onClick="Click"/>

</LinearLayout>

here is MainActivity.java

public class MainActivity extends AppCompatActivity {
    TextView autoTextIncreament;
    String stringValue="ABB";
    long intValue=20180001;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        autoTextIncreament = findViewById(R.id.txt_autoincreament);
    }

    public void Click(View view){
        autoTextIncreament.setText(getValue());
    }

    private String getValue() {
        return stringValue+String.valueOf(intValue++);
    }
}

hope this will help you.

回答2:

You can use a specific radix to parse the number into a long, increment it, and then convert it back to String.

If you're using all letters, then you can use 36 as the radix:

long number = Long.parseLong("ABB20180001", 36);

String incremented = Long.toString(number + 1, 36).toUpperCase();//"ABB20180002"

It's possible that your number is just a hexadecimal number. In that case, you can use 16 as the radix instead of 36 as shown above.

Note that if ABB is just a prefix, then the above won't work (incrementing by 20 will return ABB2018000L).

If "ABB" is just a static prefix, then you can use

//if the prefix changes, a regex will be needed
String incremented = "ABB" + (Long.parseLong(string.replace("ABB", "")) + 1)

And finally, if "ABB" can change, you can use a regex like this (the example below assumes that prefix is of length 3, change accordingly):

String s = "ABB20180001";
String[] parts = s.split("(?<=[A-Z]{3})"); //split after a sequence of 3 letters
String res = parts[0] + (Long.parseLong(parts[1]) + 1);