利用的是接口回调功能

在Fragment里要写回调，具体代码

package com.example.fragmentdemo;import android.os.Bundle;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;/** * A simple {
    @link android.support.v4.app.Fragment} subclass. *  */public class Left extends Fragment {    private TextView tv;    @Override    public void onCreate(Bundle savedInstanceState) {        // TODO Auto-generated method stub        super.onCreate(savedInstanceState);    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,            Bundle savedInstanceState) {            View v = inflater.inflate(R.layout.fragment_left, container, false);            tv = (TextView) v.findViewById(R.id.tv_left);        return v;    }    @Override    public void onPause() {        // TODO Auto-generated method stub        super.onPause();    }    //接口的作用就是把自己的值给外部用    public void getTv(CallBack c){        c.getText(tv.getText().toString());    }        //声明回调接口    public interface CallBack{        public void getText(String msg);    }}

然后在Acitivity里写获取Fragment的值

package com.example.fragmentdemo;import com.example.fragmentdemo.Left.CallBack;import android.os.Bundle;import android.support.v4.app.FragmentActivity;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentTransaction;import android.view.View;import android.view.View.OnClickListener;import android.widget.Toast;public class MainActivity extends FragmentActivity {    private FragmentManager fm;    private FragmentTransaction ft;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        fm = getSupportFragmentManager();        ft = fm.beginTransaction();        final Left left = new Left();        ft.add(R.id.left, left, "left");        ft.commit();        findViewById(R.id.right).setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View arg0) {                left.getTv(new CallBack() {                                        @Override                    public void getText(String msg) {                        Toast.makeText(MainActivity.this,msg,0).show();                                            }                });                            }        });    }}