打开一个app就闪退
最近在学android，这边有个小问题,打开这个应用就闪退是什么原因？
package com.example.linearlayouttest;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.Button;
import android.widget.LinearLayout;
public class LinearLayoutTest extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_linear_layout_test);
LinearLayout root =(LinearLayout)findViewById(R.id.root);
Button bn1=(Button)findViewById(R.id.bn1);
bn1.setText(R.string.bn1);
root.addView(bn1);
Button bn2=(Button)findViewById(R.id.bn2);
bn2.setText(R.string.bn2);
root.addView(bn2);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.linear_layout_test, menu);
return true;
}
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="bottom|center_horizontal"
android:id="@+id/root"
>
<Button
android:id="@+id/bn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/bn1"
/>
<Button
android:id="@+id/bn2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/bn2"
/>
<Button
android:id="@+id/bn3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/bn3"
/>
<Button
android:id="@+id/bn4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/bn4"
/>
</LinearLayout>
LinearLayout root =(LinearLayout)findViewById(R.id.root);
root.addView(bn1);
root.addView(bn2);
