activity之间回传数据

bt.setOnClickListener(new OnClickListener() {		
			
			public void (View v) {
				Intent i=new Intent(MainActivity.this, SecondActivity.class);
				startActivityForResult(i, 0);
			}
		});

bt2.setOnClickListener(new OnClickListener() {			
			
			public void (View v) {
				
				Intent i=new Intent();
				i.putExtra("back_data", "back_data**ok");
				setResult(RESULT_OK, i);
				finish();
			}
		});

	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		super.onActivityResult(requestCode, resultCode, data);
		switch (requestCode) {
		case 0:
			if (resultCode==RESULT_OK) {
				String back_data=data.getStringExtra("back_data");
				Log.d("back_data", back_data);
			}
			break;
		default:
			break;
		}
	}