栗子——Activity的三级跳转&值的传递

需求分析

从MainActivity-->BActivity-->CActivity-->MainActivity
也就是说跳到第三个界面后跳回到第一个界面，并把值从第三个界面传到第一个界面，没错就是这个骚操作~

栗子惯例，先上GIF

MainActivity.java

public class MainActivity extends Activity {
    private Button btnOne;
    private TextView tvContentOne;
    private final int FIRST_REQUEST_CODE = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnOne = (Button) this.findViewById(R.id.btnOne);
        tvContentOne = (TextView) this.findViewById(R.id.tvContentOne);
        btnOne.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                //跳转到第二个界面，并把值传过去
                Intent intent = new Intent(MainActivity.this,BActivity.class);
                intent.putExtra("One", "我是从第一个传过来的内容");
                startActivityForResult(intent, FIRST_REQUEST_CODE);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        //接受从第三个界面的返回值
        if(requestCode==FIRST_REQUEST_CODE && resultCode==Activity.RESULT_FIRST_USER){
            if (data != null) {
                tvContentOne.setText(data.getStringExtra("request"));
            }
        }
        //接受从第二个界面的返回值
        else if(requestCode==FIRST_REQUEST_CODE && resultCode==Activity.RESULT_OK){
            if (data != null) {
                tvContentOne.setText(data.getStringExtra("request"));
            }
        }
    }
}

BActivity.java

public class BActivity extends Activity{
    Button btnTwo;
    Button btnTwo2;
    TextView tvContentTwo;
    private final int SECOND_REQUEST_CODE = 2;
    private String text;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_b);
        btnTwo = (Button) findViewById(R.id.btnTwo);
        btnTwo2 = (Button) findViewById(R.id.btnTwo2);
        tvContentTwo = (TextView) findViewById(R.id.tvContentTwo);
        text = getIntent().getStringExtra("One");
        if(text != null){
            //设置第一个界面传过来的内容
            tvContentTwo.setText(text);
        }
        btnTwo.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                //返回第一个界面，把值传过去
                Intent intent = new Intent();
                intent.putExtra("request", "我是从第二个界面返回的内容");
                setResult(Activity.RESULT_OK,intent);
                finish();
            }
        });
        btnTwo2.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                //跳转到第三个界面，把第二个界面的内容传过去
                Intent intent = new Intent(BActivity.this,CActivity.class);
                intent.putExtra("Two", "我是从第二个界面传过来的内容");
                startActivityForResult(intent, SECOND_REQUEST_CODE);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        //关键的地方，接收到第三个界面传过来的值，并把值传回第一个界面，并关闭第二个界面
        if(requestCode==SECOND_REQUEST_CODE && data != null){
            if (data != null) {
                setResult(Activity.RESULT_FIRST_USER, data);
                finish();
            }
        }
    }
}

CActivity.java

public class CActivity extends Activity{
    Button btnThree;
    TextView tvContentThree;
    private String text;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_c);
        btnThree = (Button) findViewById(R.id.btnThree);
        tvContentThree = (TextView) findViewById(R.id.tvContentThree);
        text = getIntent().getStringExtra("Two");
        if(text != null){
            //设置第二个界面传过来的值
            tvContentThree.setText(text);
        }
        btnThree.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                //把值传回第二个界面，由第二个界面传回第一个界面
                Intent intent = new Intent();
                intent.putExtra("request", "我是从第三个界面返回的内容");
                setResult(Activity.RESULT_FIRST_USER,intent);
                finish();
            }
        });
    }
}

总结：开发中的小技巧，希望对大家有帮助~~

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