首次进入

 util = new SharePreferenceUtil(this, "saveUser");
        mLocalActivityManager = getLocalActivityManager();
        if(util.getisFirst()){
            Intent intent = new Intent(MainActivity.this,WelcomeActivity.class);
            startActivity(intent);
            util.setIsFirst(false);
        }

SharePreferenceUtil

package com.cn.daming.deskclock.activity.util;

import android.content.Context;
import android.content.SharedPreferences;

public class SharePreferenceUtil {
    private SharedPreferences sp;
    private SharedPreferences.Editor editor;

    public SharePreferenceUtil(Context context, String file) {
        sp = context.getSharedPreferences(file, context.MODE_PRIVATE);
        editor = sp.edit();
    }
    
    // �Ƿ��һ�����б�Ӧ��
    public void setIsFirst(boolean isFirst) {
        editor.putBoolean("isFirst", isFirst);
        editor.commit();
    }

    public boolean getisFirst() {
        return sp.getBoolean("isFirst", true);
    }
}