Android Studio中Activity之间为什么无法传送数据？

Main1Activity、Main2Activity可以互相跳转，但Main1Activity无法向Main2Activity传送数据。

在Main1Activity中直接这样写bundle.putString("snameText", string)，在Main2Activity中可以接收数据。

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.EditText;

public class Main1Activity extends ActionBarActivity {

    private Intent intent = new Intent();
    private Bundle bundle = new Bundle();//新建Bundle

    private EditText snameText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main1);

        snameText = (EditText) findViewById(R.id.snameText);

        bundle.putString("snameText", snameText.getText().toString());

    }

    public void confirmMain1(View v) {
        intent.setClass(Main1Activity.this, Main2Activity.class);
        intent.putExtras(bundle);
        startActivity(intent);
    }

}





import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;


public class Main2Activity extends Activity {

    private Intent intent = new Intent();
    private Bundle bundle = new Bundle();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        bundle = this.getIntent().getExtras();

        String snameText = bundle.getString("snameText");
        TextView snameView = (TextView) findViewById(R.id.snameView);
        snameView.setText(snameView.getText().toString() + snameText.toString());
    }

    public void returnMain2(View v) {
        intent.setClass(Main2Activity.this, Main1Activity.class);
        startActivity(intent);
    }

}

新手不是很会