Android Activity

MainActivity.java

package com.example.mulactivity;

import android.os.Bundle;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends Activity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    public void openActivity(View v){
        Intent intent= new Intent();
        //intent.setClassName("com.example.mulactivity", "com.example.mulactivity.OtherActivity");
        intent.setClass(this, OtherActivity.class);
        //2 intent.setClassName(this, "com.example.mulactivity.OtherActivity");
        //3 intent.setComponent(new ComponentName(this, OtherActivity.class));
        intent.putExtra("lala", "gogo");
        intent.putExtra("lala2", 999);
        Bundle bundle=new Bundle();
        bundle.putString("company", "Juice");
        bundle.putInt("number",20);
        intent.putExtras(bundle);
        //startActivity(intent);
        startActivityForResult(intent,200);
        //setContentView(R.layout.asdfmain);
    }
    protected void onActivityResult(int requestCode, int resultCOde, Intent data){
        String result=data.getStringExtra("result");
        String resulttt=String.valueOf(requestCode);
        Toast.makeText(this, resulttt, 1).show();
    }

}

OtherActivity.java

package com.example.mulactivity;

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

public class OtherActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.asdfmain);
        Intent intent=getIntent();
        String lala=intent.getStringExtra("company");
        int number=intent.getIntExtra("number", 0);
        int number2=intent.getIntExtra("number2", 0);
        
        TextView textView=(TextView)this.findViewById(R.id.textView1);
        textView.setText("gongsiming: "+lala+"; number: "+number+"; number2: "+number2);
        //textView.setText("gongsiming: "+company+"; number: "+number+"; number2: "+number2);
    }
    
    public void closeActivity(View v)
    {
        Intent data=new Intent();
        data.putExtra("result", "kkkkkk");
        setResult(30,data);
        this.finish();
    }
}

Life cycle

Three states: running, suspend, stop. Whatever states the activity is in, the activity will not be killed if the memory is sufficient. 

There are seven state changing functions listed as follow.

To keep some temporary result when the accident occurs, we may use the function below. 

Orientation Shift