Question

我正在尝试通过按下“添加”按钮（b1）为我的linearlayout添加一个复选框。我的应用程序一直在线l1.addView(ckbx);崩溃（日志在这里发送'但不是'这里2'）。有什么想法吗？

谢谢：）

这是我的代码：

package com.example.todolist;

import android.os.Bundle;
import android.app.ActionBar.LayoutParams;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ScrollView;
import android.widget.TableRow;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener{

private LinearLayout l1;
private EditText e1;
private Button b1;
private Button b2;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
    l1 = (LinearLayout)findViewById(R.layout.activity_main);
    e1 = (EditText)findViewById(R.id.editText1);
    b1 = (Button)findViewById(R.id.button1);    
    b2 = (Button)findViewById(R.id.button2);

    // Buttons should register with listener
    b1.setOnClickListener(this);
    b2.setOnClickListener(this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public void onClick (View v) {

    switch(v.getId())
    {   
        // Starts Service.class 
        case R.id.button1: 
            Toast.makeText(this, "Add pressed", Toast.LENGTH_SHORT).show();
            // Create new check box in layout           
            CheckBox ckbx = createNewCheckBox(e1.getText().toString());
            Log.d("here","here now");
            l1.addView(ckbx);
            Log.d("here 2","here now 2");
                            setContentView(l1);

            break;

        case R.id.button2: 
            Toast.makeText(this, "Delete pressed", Toast.LENGTH_SHORT).show();
            break;
    }
}

// User defined method to create a new check box in the linear layout page
private CheckBox createNewCheckBox(String text) {
    final LayoutParams lparams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    final CheckBox checkBox = new CheckBox(this);
    checkBox.setLayoutParams(lparams);
    checkBox.setText(text);
    return checkBox;
}
}

Answer 1

l1 = (LinearLayout)findViewById(R.layout.activity_main);

更改为

l1 = (LinearLayout)findViewById(R.id.yourlinearlayoutidfromxml);

您还应该发布堆栈以及问题，因为会记录有关崩溃的相关信息。怀疑NullpointerException。

对于相同的活动，你也有setContentView两次，这不是一个好的设计。

setContentView(R.layout.activity_main);

你已经拥有

l1 = (LinearLayout)findViewById(R.id.yourlinearlayoutidfromxml);

你应该删除

setContentView(l1);

Android：如何通过单击按钮添加复选框？

1 个答案: