Question

我是Android和java编程的初学者，所以我无法理解为什么我的switch语句不适用于按钮元素。

  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.Button;
  import android.widget.TextView;

  public class MainActivity extends AppCompatActivity {
  Button button1;
  Button button2;
  Button button3;
  TextView textView;


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

      button1 = (Button) findViewById(R.id.button1);
      button2 = (Button) findViewById(R.id.button2);
      button3 = (Button) findViewById(R.id.button3);
      textView = (TextView) findViewById(R.id.textView);

    View.OnClickListener onClickListener = new View.OnClickListener() {
       @Override

这是我的问题

          public void onClick(View v) {
           switch(v.getId()){
              case R.id.button1:
                  textView.setText("Button1 was pressed");
                     break;
              case R.id.button2:
                  textView.setText("Button2 was pressed");
                     break;
             case R.id.button3:
                  textView.setText("Button3 was pressed");
                     break;
                  }
               }
             };



       }
      }

如果有人帮助我，我会非常感激。

P.S。我是编程初学者

Answer 1

您尚未在setOnClickListner上写Button并确保Activity implements View.OnClickListener在下方查看我的代码。

button1.setOnClickListener(this);
button2.setOnClickListener(this);
button3.setOnClickListener(this);

使用此代码。

public class MainActivity extends AppCompactActivity implements View.OnClickListener {

    Button button1;
    Button button2;
    Button button3;
    TextView textView;

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

        button1 = (Button) findViewById(R.id.button1);
        button2 = (Button) findViewById(R.id.button2);
        button3 = (Button) findViewById(R.id.button3);
        textView = (TextView)findViewById(R.id.textview) ;

        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
        button3.setOnClickListener(this);

    }


    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.button1:
                textView.setText("Button1 was pressed");
                break;
            case R.id.button2:
                textView.setText("Button2 was pressed");
                break;
            case R.id.button3:
                textView.setText("Button3 was pressed");
                break;
        }

    }
}

Switch语句在使用Button的Android工作室中不起作用

1 个答案: