1.啟動(dòng)一個(gè)activity并從它中拿到回執(zhí)的值

通過startActivityForResult啟動(dòng)activity绞蹦，從onActivityResult拿到返回值

代碼示例

public class FirstActivity extends AppCompatActivity {
    private static final int REQUESTCODE = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
        findViewById(R.id.startIntent).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
                startActivityForResult(intent, REQUESTCODE);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case REQUESTCODE:
                if (resultCode == RESULT_OK) {
                    String returnData = data.getStringExtra("RETURN_DATA");
                    Toast.makeText(this, "return data: " + returnData, Toast.LENGTH_SHORT).show();
                }
                break;
            default:
                break;

        }
    }
}

通過setResult向上一個(gè)活動(dòng)返回?cái)?shù)據(jù)

public class SecondActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        findViewById(R.id.text).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.putExtra("RETURN_DATA", "返回?cái)?shù)據(jù)給第一頁(yè)");
                setResult(RESULT_OK, intent);
                finish();
            }
        });
    }
}

2.活動(dòng)被回收了的處理

代碼示例

public class FirstActivity extends AppCompatActivity {

    private String tempData = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
        tempData = "內(nèi)存回收之前需要保存的測(cè)試數(shù)據(jù)";
        if (savedInstanceState != null) {
            tempData = savedInstanceState.getString("tempdata");
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putString("tempdata", tempData);
    }
}

3.啟動(dòng)模式

在清單文件中添加 android:launchMode

• standard
• singleTop
• singleTask
• singleInstance

standard

系統(tǒng)不在乎是否已經(jīng)在返回椗缰冢總存在泉蝌，每次啟動(dòng)都會(huì)重新創(chuàng)建一個(gè)實(shí)例

singleTop

啟動(dòng)活動(dòng)時(shí)屋剑，如果返回棧頂已經(jīng)是該活動(dòng)呛谜，則不在重新創(chuàng)建新的活動(dòng)风罩。如果不在棧頂岁忘，則仍然會(huì)再次創(chuàng)建該活動(dòng)。

singleTask

系統(tǒng)會(huì)在返回棧中檢查是否存在該活動(dòng)深员，如果存在负蠕，則直接使用它，并把這個(gè)活動(dòng)之上的其他活動(dòng)統(tǒng)統(tǒng)出棧倦畅。如不存在遮糖，則重新創(chuàng)建。

singleInstance

啟用一個(gè)新的返回棧來管理這個(gè)活動(dòng)叠赐。如果有上個(gè)活動(dòng)A(standard)->B(singleInstance)->C(standard)依次點(diǎn)擊跳轉(zhuǎn)完欲账，點(diǎn)擊back鍵回退時(shí)，回退順序?yàn)镃->A->B芭概。因?yàn)锳C為同一個(gè)棧赛不，C出棧后自然會(huì)顯示A，A出棧后才會(huì)顯示另一個(gè)棧B谈山。

4.BaseActivity俄删，ActivityCollector管理啟動(dòng)的activity

代碼示例

public class ActivityCollector {
    private static List<Activity> activities = new ArrayList<>();

    public static void addActivity(Activity activity) {
        activities.add(activity);
    }

    public static void removeActivity(Activity activity) {
        activities.remove(activity);
    }

    /**
     * 退出程序
     */
    public static void finishAll() {
        for (Activity activity : activities) {
            if (!activity.isFinishing()) {
                activity.finish();
            }
        }
    }

    /**
     * 保證程序完全退出，殺掉進(jìn)程,只能用于殺掉當(dāng)前程序進(jìn)程
     */
    public static void killProcess (){
        android.os.Process.killProcess( android.os.Process.myPid());

    }
}

public class BaseActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //打印當(dāng)前活動(dòng)的名稱
        Log.d("BaseActivity", "Current Activity Name:  " + getClass().getSimpleName());
        ActivityCollector.addActivity(this);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }
}

5.啟動(dòng)activity較優(yōu)方式

代碼示例

public class SecondActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
    }

    public static void startSecondActivity(Context context, String param1, String param2) {
        Intent intent = new Intent(context, SecondActivity.class);
        intent.putExtra("param1", param1);
        intent.putExtra("param2", param2);
        context.startActivity(intent);
    }
}