android,没报错，怎么不能跑？

Question

MainActivity.java

 package com.example.ch02_listview;


import android.app.ListActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;


public class MainActivity extends ListActivity {
    private String[] mListStr={"小胡","男","19","杭州","[e-mail]","15757188543"};
    ListView mListView=null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mListView=getListView();
        setListAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mListStr));
        mListView.setOnItemClickListener(new AdapterView.OnItemClickListener(){
            @Override
            public void onItemClick(AdapterView<?> adapterView,View view,int position,long id) {
                Toast.makeText(MainActivity.this,"你选择了:"+mListStr[position],Toast.LENGTH_LONG).show();
            }
        });
    }


    @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 boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

Answer 1

你这个是继承的ListActivity, getListView()是ListActivity的方法，这里没问题
问题应该是在onCreate方法里setContentView(R.layout.activity_main); 这一行，既然用了ListActivity就已经有了一个默认布局了，直接删掉这一行，书里应该没有这一行吧
activity_main这个布局文件如果没地方用到也可以删了