android-查看关键字是否存在的文件

package zhang.example;import java.io.File;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;public class search extends Activity {private Button ok;private TextView tv;private EditText et;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                ok=(Button)findViewById(R.id.button1);        tv=(TextView)findViewById(R.id.textView1);        et=(EditText)findViewById(R.id.editText1);                ok.setOnClickListener(new Button.OnClickListener(){@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubString key=et.getText().toString();if(key.equalsIgnoreCase("")){Toast.makeText(search.this, "xxx", Toast.LENGTH_SHORT).show();}else{tv.setText(searchFile(key));}}});            }    private String  searchFile(String key){    String result="";    File[] files=new File("/").listFiles();    for(File f:files){    if(f.getName().indexOf(key)>=0){    result+=f.getPath()+"\n";    }    }    if(result.equals(""))    result="no";return result;        }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    ><TextView      android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:text="key word"    /><EditText android:layout_height="wrap_content" android:layout_width="fill_parent" android:id="@+id/editText1"></EditText><Button android:text="Button" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button><TextView  android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView></LinearLayout>