onBackPressed() 使用

Posted 2022-12-03 changhaiSmile

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；

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();