onBackPressed() 使用

 

onBackPressed() : 当手机按下back键时，执行此方法。

 

用此方法时 ：有super.onBackPressed() 时 不能把在此方法中设置的 intent 传回上一个Activity ，

                        因此 去掉super.onBackPressed()  在末尾加上finish（）；

                        在上一个activity中用onActivityResult() 方法接受上此Activity的onBackPressed()方法传回去的intent，

                         在onBackPressed（）设置resultCode  在上一个Activity 的OnActivityResult（）中验证；

 

 

接受Activity：

package com.orient;

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

public class TestProjectActivity extends Activity {
	String result;
	TextView view;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		view = (TextView) findViewById(R.id.text);

		Button back = (Button) findViewById(R.id.button);
		back.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {

				Intent intent = new Intent(TestProjectActivity.this,
						CopyOfTestProjectActivity.class);
				startActivityForResult(intent, 1111);
			}
		});
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		super.onActivityResult(requestCode, resultCode, data);
		if (requestCode == 1111 && resultCode == 111 && data != null) {
			result = data.getStringExtra("activity2");
			view.setText(result);
		}
	}
}

传值Activity：

package com.orient;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class CopyOfTestProjectActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main2);
        
        Log.v("Test21", "Display onBackPressed");
            }

	@Override
	public void onBackPressed() {
		Intent intent=new Intent();
		intent.putExtra("activity2", "TestText");
		setResult(111, intent);
		finish();
	}

}