Question

基本上我想要两个观点。一个视图用于画布，用于绘制矩形和另一个视图或在绘制矩形时添加新的editText框。当我运行我的程序时，出现错误“java.lang.NullPointerException”。是否可以将edittext框添加到画布视图中，以便我只保留一个视图？

我的代码如下：

public class MainActivity extends Activity {
        public static DrawRect DR;

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

        DR = new DrawRect(this);

        rectbutton = (Button) findViewById(R.id.rectbutton);

        RelativeLayout mainLayout = (RelativeLayout) findViewById(R.id.RelativeLayout);

        RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.MATCH_PARENT,
                RelativeLayout.LayoutParams.MATCH_PARENT);


        lp.addRule(RelativeLayout.BELOW, R.id.rectbutton);

        DR.setLayoutParams(lp);

        mainLayout.addView(DR);


    rectbutton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                     addRect(); // in my DrawRect class i have this method to draw rect on canvas
              addEditText();

                     }// onclick

        });
}

    private void addEditText(){

        RelativeLayout editTextLayout = new RelativeLayout(this);
          EditText editText = new EditText(this);
          editTextLayout.addView(editText);
           mainLayout.addView(editTextLayout);

    }
}

请咨询。谢谢。

Answer 1

哪一行给出错误。如果它在

中给出错误

 mainLayout.addView(editTextLayout);

表示mainLayout为null。您可以在画布中添加EditText。问题在于

RelativeLayout mainLayout = (RelativeLayout) findViewById(R.id.RelativeLayout);

检查布局xml中的id。

Android：添加EditText以查看错误

1 个答案: