Activity 之间的交互

startActivityForResult(intent, state_tag);

public class MainActivity extends Activity {
    private TextView tv = null;
    private int state_tag = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = (TextView)findViewById(R.id.textView);
        Button button = (Button)findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
                                
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent i = new Intent(MainActivity.this, SecondActivity.class);
                Bundle bundle = new Bundle();
                bundle.putString("content", tv.getText().toString());
                i.putExtra("bundle", bundle);
                startActivityForResult(i, state_tag);
            }
        });
    }
    @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
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode == state_tag)
        {
            if(resultCode == RESULT_OK)
            {
                                    
                Log.i("MainActivity", data.getBundleExtra("bundle2").getString("newContend"));
                tv.setText(data.getBundleExtra("bundle2").getString("newContend"));
            }
            else
            {
                Log.i("MainActivity", "in else:");
                return;
            }
        }
    }
}

package com.example.intenttest;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class SecondActivity extends Activity {
    private EditText editText = null;
    private Button okButton = null;
    private Button cancelButton = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
          
        editText = (EditText)findViewById(R.id.editText);
        okButton = (Button)findViewById(R.id.okButton);
        cancelButton = (Button)findViewById(R.id.cancelButton);
        Intent i = getIntent();
        editText.setText(i.getBundleExtra("bundle").getString("content"));
        okButton.setOnClickListener(new View.OnClickListener() {
              
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent i = new Intent(SecondActivity.this, MainActivity.class);
                Bundle bundle = new Bundle();
                bundle.putString("newContent", String.valueOf(editText.getText()));
                i.putExtra("bundle2", bundle);
                setResult(RESULT_OK, i);
                finish();
            }
        });
        cancelButton.setOnClickListener(new View.OnClickListener() {
              
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                setResult(RESULT_CANCELED);
                finish();
            }
        });
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
    }
}