Question

我正在尝试显示一个变量，用户应该能够使用2个按钮向上和向下计数。这是我的代码。问题是它似乎不起作用。如果你点击“minues”然后出现“1”，如果你点击“加”则没有任何反应。非常感谢！

我知道切换可能不是最优雅的解决方案，但我还是想尝试一下

public class StoryCreator extends Activity implements OnClickListener {

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

    Button b1 = (Button) findViewById(R.id.minus);   
    b1.setOnClickListener(this);

    Button b2 = (Button) findViewById(R.id.plus);   
    b2.setOnClickListener(this);

}

    public void onClick(View v) {

        int Zahl = 1;    

        TextView objekt = (TextView) findViewById(R.id.textView1);  
        objekt.setText("0");

       // Perform action on click
          switch(v.getId())
          {

             case 1: 
                                    Zahl = Zahl-1;
                                    break;
             case 2:
                                    Zahl = Zahl+1;
                                    break;
             default:           
                                    break;
         }


            switch(Zahl) {
            case -1: 
                objekt.setText("-1");
                break;
            case 0: 
                objekt.setText("0");
                break;
            case 1:
                objekt.setText("1");
                break;              
            case 2:
                objekt.setText("2");
                break;      
            case 3:
                objekt.setText("3");
                break;      

            }

Answer 1

将您的开关案例更改为：

   // Perform action on click
      switch(v.getId())
      {

         case R.id.minus: 
             Zahl = Zahl-1;
              break;
         case R.id.plus:
             Zahl = Zahl+1;
             break;
         default:           
             break;
     }

使用Button id代替1,2来执行按钮单击

的操作

Answer 2

你也设置了

 int Zahl = 1;

每按一次按钮，Zahl的值可能只有0或1

public class StoryCreator extends Activity implements OnClickListener {


int mValue = 0;

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

    Button b1 = (Button) findViewById(R.id.minus);   
    b1.setOnClickListener(this);

    Button b2 = (Button) findViewById(R.id.plus);   
    b2.setOnClickListener(this);

}

    public void onClick(View v) {


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

       // Perform action on click
          switch(v.getId())
          {

             case R.id.plus: 
                                    mValue++;
                                    break;
             case R.id.minus:
                                    mValue--;
                                    break;
             default:           
                                    break;
         }

          objekt.setText(mValue);
}

Answer 3

嗯，您的代码中存在许多问题：

您使用错误的方式引用按钮
您没有正确存储以前的值
您没有正确增加以前的值
等。：）

尝试使用此代码：

public class StoryCreator extends Activity implements OnClickListener {

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

        Button b1 = (Button) findViewById(R.id.minus);   
        b1.setOnClickListener(this);

        Button b2 = (Button) findViewById(R.id.plus);   
        b2.setOnClickListener(this);

        textView = (TextView) findViewById(R.id.textView1);
        textView.setText("0"); //initial value

    }

    public void onClick(View v) {

        int Zahl = Integer.parseInt(textView.getText().toString());    

       // Perform action on click
          switch(v.getId())
          {

             case R.id.plus: 
                                    Zahl++;
                                    break;
             case R.id.minus:
                                    Zahl--;
                                    break;
             default:           
                                    break;
         }

         textView.setText(String.valueOf(Zahl));
    }
}

Answer 4

更简洁的方法是删除“implements View.OnClickListener”并为每个按钮创建单击侦听器。

此外，上述解决方案仍然没有实际增加单个变量。如果您希望增量在实例之间保持不变，则需要将其变为静态。

以下内容可为您提供所需内容，并且无需使用View.OnClickListener污染您的活动即可干净利落。

public class StoryCreator extends Activity {
    TextView textView;
    private static int zahl = 0;

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

        Button minus = (Button) findViewById(R.id.minus);   
        minus.setOnClickListener(minusClickListener);

        Button plus = (Button) findViewById(R.id.plus);   
        plus.setOnClickListener(plusClickListener);

        textView = (TextView) findViewById(R.id.textView1);
        textView.setText("0"); //initial value

    }

    private View.OnClickListener minusClickListener= new View.OnClickListener() {
        public void onClick(View v) {
              zahl--;
        }
    } 

    private View.OnClickListener plusClickListener = new View.OnClickListener() {
        public void onClick(View v) {
             zahl++;
        }
    }

Answer 5

对不起它有点乱，但这应该完全符合你的要求。

public class CountUpAction extends AbstractAction {
      /** Constructor */
      public CountUpAction(String name, String shortDesc, Integer mnemonic) {
         super(name);
         putValue(SHORT_DESCRIPTION, shortDesc);
         putValue(MNEMONIC_KEY, KeyEvent.VK_NUMPAD4);
      }

      @Override
      public void actionPerformed(ActionEvent e) {
          addKeyListener(new KeyAdapter() {
                public void keyPressed(KeyEvent evt) {
                    switch(evt.getKeyCode()) {
                    case KeyEvent.VK_NUMPAD1:

            //original count
            count += 1;
            tfCount.setText(count + "");

                    }
                }
              });
      }
   }

   public class CountDownAction extends AbstractAction {
      /** Constructor */
      public CountDownAction(String name, String shortDesc, Integer mnemonic) {
         super(name);
         putValue(SHORT_DESCRIPTION, shortDesc);
         putValue(MNEMONIC_KEY, KeyEvent.VK_NUMPAD5);
      }

      @Override
      public void actionPerformed(ActionEvent e) {
          addKeyListener(new KeyAdapter() {
            public void keyPressed(KeyEvent evt) {
                switch(evt.getKeyCode()) {
                case KeyEvent.VK_NUMPAD2:

          //original count
          count -= 1;
          tfCount.setText(count + "");

                }
            }
          });
      }
 Action countUpAction = new CountUpAction("Count Up",
            "", new Integer(KeyEvent.VK_ENTER));
      Action countDownAction = new CountDownAction("Count Down",
            "", new Integer(KeyEvent.VK_D));


  tfCount = new JTextField("0", 8);
      tfCount.setHorizontalAlignment(JTextField.CENTER);
      tfCount.setEditable(false);
      tfCount.setSize(100, 20);
      canvas.add(tfCount, BorderLayout.LINE_START);

  //Invisible
      JButton btnCountUp = new JButton();
      btnCountUp.setFocusable(false);
      btnCountUp.setHideActionText(true);
      btnCountUp.setContentAreaFilled(false);
      btnCountUp.setBorderPainted(false);
      canvas.add(btnCountUp, BorderLayout.NORTH);
      //Invisible
      JButton btnCountDown = new JButton();
      btnCountDown.setFocusable(false);
      btnCountDown.setHideActionText(true);
      btnCountDown.setContentAreaFilled(false);
      btnCountDown.setBorderPainted(false);

      canvas.add(btnCountDown);
      // Set actions for buttons
      btnCountUp.setAction(countUpAction);
      btnCountDown.setAction(countDownAction);

Android应用：按钮计数变量向上或向下

5 个答案: