Use this code in your App, it works for me:
DevicePolicyManager devicePolicyManager =
(DevicePolicyManager) getSystemService(Context.DEVICE_POLICY_SERVICE);
ComponentName demoDeviceAdmin = new ComponentName(this, name of activity);
devicePolicyManager.setPasswordQuality(
demoDeviceAdmin,DevicePolicyManager.PASSWORD_QUALITY_UNSPECIFIED);
devicePolicyManager.setPasswordMinimumLength(demoDeviceAdmin, 5);
boolean result = devicePolicyManager.resetPassword("123456",
DevicePolicyManager.RESET_PASSWORD_REQUIRE_ENTRY);
Toast.makeText(this, "button_lock_password_device..."+result, Toast.LENGTH_LONG).show();
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…