Lock Pattern

o build.gradle

implementation 'me.zhanghai.android.patternlock:library:2.1.2'

o Util.java

public class Util {

    private static final String LOCK_PATTERN = "lockpattern";

    private static Context mContext;

    public static void init(Context appContext) {
        mContext = appContext;
    }

    public static Context getContext(){
        return mContext;
    }

    private static SharedPreferences getSharedPreferences() {
        return mContext.getSharedPreferences("roundtalk", Context.MODE_PRIVATE);
    }

    public static void setLockPattern(String lockPattern) {
        SharedPreferences.Editor editor = getSharedPreferences().edit();
        editor.putString(LOCK_PATTERN, lockPattern).apply();
    }

    public static String getLockPattern() {
        return getSharedPreferences().getString(LOCK_PATTERN, "");
    }

}

o  LockPatternSetActivity.java

public class LockPatternSetActivity extends SetPatternActivity {
    private static final String TAG = LockPatternSetActivity.class.getSimpleName();

    @Override
    protected void onSetPattern(List<PatternView.Cell> pattern) {
        super.onSetPattern(pattern);
        String patternSha1 = PatternUtils.patternToSha1String(pattern);
        Log.d(TAG, "patternSha1 : "+Util.getLockPattern());
        if(Util.getLockPattern().isEmpty())
            Util.setLockPattern(patternSha1);
    }
}

o LockPatternConfirmActivity.java

public class LockPatternConfirmActivity extends ConfirmPatternActivity {

    @Override
    protected boolean isStealthModeEnabled() {
        // TODO: Return the value from SharedPreferences.
        return false;
    }

    @Override
    protected boolean isPatternCorrect(List<PatternView.Cell> pattern) {
        // TODO: Get saved pattern sha1.
        String patternSha1 = Util.getLockPattern();
        if(TextUtils.equals(PatternUtils.patternToSha1String(pattern), patternSha1))
            Toast.makeText(this, "Pattern is correct.", Toast.LENGTH_SHORT).show();

        return TextUtils.equals(PatternUtils.patternToSha1String(pattern), patternSha1);
    }

    @Override
    protected void onForgotPassword() {
        // lock pattern forgot...reset pattern
        startActivity(new Intent(this, LockPatternSetActivity.class));

        // Finish with RESULT_FORGOT_PASSWORD.
        super.onForgotPassword();
    }

}

o MainActivity.java

public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();

    private Button lockpattern;


    @TargetApi(Build.VERSION_CODES.P)
    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Util.init(this);

        lockpattern = findViewById(R.id.lockpattern);
        lockpattern.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(Util.getLockPattern().isEmpty())
                    startActivity(new Intent(MainActivity.this, LockPatternSetActivity.class));
                else
                    startActivity(new Intent(MainActivity.this, LockPatternConfirmActivity.class));
            }
        });
        


    }

}