两个Activity之间通过Intent相互（双向）传递数据

冷不防 2022-07-29 09:17 175阅读 0赞

两个Activity通过Intent相互交换数据，在Activity中用一个Button 选择是否接受数据，不能直接写在onCreate中否则在Activity1 中获取从Activity2发送的数据时会崩溃，原因是因为在Activity中会通过Intent再创建一个Activity1的界面 而Activity1在内存中是存在的。

package com.example.he.text2;
    
    import android.app.Activity;
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.Toast;
    
    /**
     * Created by he on 2016/3/19.
     */
    public class FirstActivity extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.firstlayout);
            Button first_button =(Button)findViewById(R.id.first_button);
            Button second_button=(Button)findViewById(R.id.second_button);
    
            //向SecondActivity传数据的按钮
            first_button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent =new Intent(FirstActivity.this,SecondActivity.class);
                    intent.putExtra("first_action","hello secondActivity");
                    startActivity(intent);
                }
            });
    
            //从SecondActivity得到数据的按钮
            second_button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent =new Intent(FirstActivity.this,SecondActivity.class);
                    startActivityForResult(intent,1);
                }
            });
    
    
        }
    
    
    
        //读取返回信息
        @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            switch (requestCode){
                case  1:
                    if (resultCode==RESULT_OK){
                        String s=data.getStringExtra("data_return");
                        Toast.makeText(FirstActivity.this, s, Toast.LENGTH_SHORT).show();
    //                    Log.i("FirstActivity",s);
                    }
                    break;
            }
        }
    }

package com.example.he.text2;
    
    import android.app.Activity;
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.Toast;
    
    /** * Created by he on 2016/3/19. */ public class SecondActivity extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.secondlayout);
    
            Button button1 = (Button) findViewById(R.id.button1);
            Button button2 = (Button) findViewById(R.id.button2);
    
            button1.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent2 = new Intent();
                    intent2.putExtra("data_return", "hello firstActivity");
                    setResult(RESULT_OK, intent2);
                    finish();
                }
            });
    
            button2.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent1 = getIntent();
                    String data = intent1.getStringExtra("first_action");
                    Toast.makeText(SecondActivity.this, data, Toast.LENGTH_SHORT).show();
    //                Log.i("SecondActivity", data);
                }
            });
    
        }
    
    
        @Override
        public void onBackPressed() {
            Intent intent2 = new Intent();
            intent2.putExtra("data_return", "hello firstActivity");
            setResult(RESULT_OK, intent2);
            finish();
        }
    }