android基本知识(一)

Intent intent = new Intent(MainActivity.this,SecondActivity.class);
startActivity(intent);

Intent intent2 = new Intent("com.example.intenttest.ACTION_START");
intent2.addCategory("com.example.intenttest.MY_CATEGORY");
startActivity(intent);

 <activity 
      android:name=".SecondActivity"
      android:label="@string/app_name">
      <intent-filter >
        <action android:name="com.example.intenttest.ACTION_START"/>
        <category android:name="android.intent.category.DEFAULT"/>
        <category android:name="com.example.intenttest.MY_CATEGORY"/>
      </intent-filter>
</activity>

Intent intent = new Intent(MainActivity.this,SecondActivity.class);
startActivityForResult(intent,1);

				Intent intent = new Intent();
				intent.putExtra("extra_data", "我返回数据了");
				setResult(RESULT_OK, intent);
				finish();

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		switch (requestCode) {
		case 1:
			if(RESULT_OK == resultCode){
				String extra_data = data.getStringExtra("extra_data");
				Log.i("extra_data",extra_data);
			}
			break;
		default:
			break;
		}
	};

public class MainActivity extends ActionBarActivity {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		Log.i("Life Tag", "OnCreate");
		Button normalButton = (Button)findViewById(R.id.normal_button);
		Button dialogButton = (Button)findViewById(R.id.dialog_button);
		EditText tempText = (EditText)findViewById(R.id.login_name);
		if(null != savedInstanceState){//利用Bundle对象来还原之前在内存回收活动时，保存的关键数据
			String tempData = savedInstanceState.getString("tempName");
			Log.i("Tag", tempData);
			tempText.setText(tempData);
		}
		//测试安卓活动的七个生命周期，利用对话框活动和完全覆盖活动来区别onPause和onStop方法
		normalButton.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Intent intent = new Intent(MainActivity.this,NormalActivity.class);
				startActivity(intent);
			}
		});
		dialogButton.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Intent intent = new Intent(MainActivity.this,DialogActivity.class);
				startActivity(intent);
			}
		});
	}
	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		Log.i("Life Tag", "onStart");
		
	}
	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		Log.i("Life Tag", "OnResume");
	}
	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		Log.i("Life Tag", "OnPause");
	}
	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		Log.i("Life Tag", "onStop");
	}
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		Log.i("Life Tag", "onDestroy");
	}
	@Override
	protected void onRestart() {
		// TODO Auto-generated method stub
		super.onRestart();
		Log.i("Life Tag", "OnRestart");
	}
	//在内存不足时回收活动，保存其主要关键数据，这在用户体验还是比较重要的了。
	@Override
	protected void onSaveInstanceState(Bundle outState) {
		// TODO Auto-generated method stub
		super.onSaveInstanceState(outState);
		EditText tempText = (EditText)findViewById(R.id.login_name);
		String name = tempText.getText().toString();
		outState.putString("tempName", name);
		Log.i("Name_Tag", name);
	}

protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_third);
		Log.i("TAG", "The task is"+getTaskId());
		Button firstButton = (Button)findViewById(R.id.firstButton);
		firstButton.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Intent intent = new Intent(ThirdActivity.this,MainActivity.class);
				startActivity(intent);
			}
		});
	}
}