<Button
        android:id="@+id/mybutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="0dp"
        android:text="點擊顯示二維碼"
        android:textSize="20sp" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="192dp"
        android:src="@drawable/ic_launcher_background" />

    <EditText
        android:id="@+id/myeditText"
        android:layout_width="300dp"
        android:maxLines="1"
        android:layout_height="wrap_content"
        android:layout_below="@+id/mybutton"
        android:layout_centerHorizontal="true"
        android:ems="10"
        android:hint="請輸入要加載成二維碼的內容" />

public class MainActivity extends Activity implements View.OnClickListener {


    private int width = 300;
    private int height = 300;
    private ImageView imageView;
    private Bitmap bit;
    private Button mybutton;
    private EditText myeditText;


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

    }


    private void initView() {
        imageView = (ImageView) findViewById(R.id.imageView);
        mybutton = (Button) findViewById(R.id.mybutton);
        mybutton.setOnClickListener(this);
        myeditText = (EditText) findViewById(R.id.myeditText);
        myeditText.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.mybutton:
          String name=myeditText.getText().toString();
          if(name.equals("")){
              myeditText.setError("請輸入內容");
          }else{
              zxing(name);
          }

                break;
        }
    }
    private void zxing(String name){
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        Map<EncodeHintType, String> hints = new HashMap<>();
        hints.put(EncodeHintType.CHARACTER_SET, "utf-8"); //記得要自定義長寬
        BitMatrix encode = null;
        try {
            encode = qrCodeWriter.encode(name, BarcodeFormat.QR_CODE, width, height, hints);
        } catch (WriterException e) {
            e.printStackTrace();
        }
        int[] colors = new int[width * height];
           //利用for循環(huán)將要表示的信息寫出來
        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                if (encode.get(i, j)) {
                    colors[i * width + j] = Color.BLACK;
                } else {
                    colors[i * width + j] = Color.WHITE;
                }
            }
        }

        bit = Bitmap.createBitmap(colors, width, height, Bitmap.Config.RGB_565);
        imageView.setImageBitmap(bit);
    }

}