Android Generate Random String

Android Generate Random String

This post about how to  generate random char using Random class.

Random random = new Random();

This is list of char 

private static final String _CHAR = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";

Random string length

private static final int RANDOM_STR_LENGTH = 12;
This method for generate only numbers

private int getRandomNumber() {

            int randomInt = 0;

            randomInt = random.nextInt(_CHAR.length());

            if (randomInt - 1 == -1) {

                  return randomInt;

            } else {

                  return randomInt - 1;

            }

      }

This method for generate numbers with char.

    public String getRandomString(){

            StringBuffer randStr = new StringBuffer();

            for (int i = 0; i < RANDOM_STR_LENGTH; i++) {

                  int number = getRandomNumber();

                  char ch = _CHAR.charAt(number);

                  randStr.append(ch);

            }

            return randStr.toString();

      }

  

Screen Shot

Full Source Code

package com.androidbunch.generaterandomnumber;

import java.util.Random;

import android.os.Bundle;

import android.app.Activity;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.TextView;

/**

 *

 * @author VIJAYAKUMAR M

 *

 */

public class MainActivity extends Activity {

      Random random = new Random();

      private static final String _CHAR = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";

      private static final int RANDOM_STR_LENGTH = 12;

     

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_main);

            Button btn = (Button) findViewById(R.id.button1);

            btn.setOnClickListener(new OnClickListener() {

                  @Override

                  public void onClick(View v) {

                        TextView text_Random = (TextView) findViewById(R.id.textView1);

                        text_Random.setText(getRandomString());

                  }

            });

      

    }

    public String getRandomString(){

            StringBuffer randStr = new StringBuffer();

            for (int i = 0; i < RANDOM_STR_LENGTH; i++) {

                  int number = getRandomNumber();

                  char ch = _CHAR.charAt(number);

                  randStr.append(ch);

            }

            return randStr.toString();

      }

      private int getRandomNumber() {

            int randomInt = 0;

            randomInt = random.nextInt(_CHAR.length());

            if (randomInt - 1 == -1) {

                  return randomInt;

            } else {

                  return randomInt - 1;

            }

      }

}

Layout source code

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context=".MainActivity" >

    <Button

        android:id="@+id/button1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentTop="true"

        android:layout_alignRight="@+id/textView1"

        android:layout_marginTop="58dp"

        android:text="Generate Random String" />

    <TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@+id/button1"

        android:layout_centerHorizontal="true"

        android:layout_marginTop="30dp"

        android:textColor="#000000"

        android:textSize="10pt"

        android:textStyle="bold" />

</RelativeLayout>