如何通过点击activity 'b‘中的按钮将项目添加到activity 'a’中的字符串数组中，并在退出应用程序后保存项目？

public void addProject(String project) {
    // 将传递过来的项目添加到字符串数组中
    String[] newArray = new String[projectArray.length + 1];
    System.arraycopy(projectArray, 0, newArray, 0, projectArray.length);
    newArray[projectArray.length] = project;
    projectArray = newArray;

    // 更新界面显示
    // ...
}

button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        String project = "项目内容"; // 获取项目的内容
        Intent intent = new Intent(ActivityB.this, ActivityA.class);
        intent.putExtra("project", project);
        startActivity(intent);
    }
});

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

    // 获取从Activity 'b'传递过来的项目
    Intent intent = getIntent();
    if (intent != null) {
        String project = intent.getStringExtra("project");
        if (project != null) {
            addProject(project); // 调用添加项目的方法
        }
    }

    // 其他初始化操作
    // ...
}

@Override
protected void onPause() {
    super.onPause();

    // 将项目保存到SharedPreferences中
    SharedPreferences sharedPreferences = getSharedPreferences("MyPrefs", MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putInt("projectCount", projectArray.length);
    for (int i = 0; i < projectArray.length; i++) {
        editor.putString("project" + i, projectArray[i]);
    }
    editor.apply();
}

@Override
protected void onResume() {
    super.onResume();

    // 从SharedPreferences中恢复保存的项目
    SharedPreferences sharedPreferences = getSharedPreferences("MyPrefs", MODE_PRIVATE);
    int projectCount = sharedPreferences.getInt("projectCount", 0);
    projectArray = new String[projectCount];
    for (int i = 0; i < projectCount; i++) {
        projectArray[i] = sharedPreferences.getString("project" + i, "");
    }

    // 更新界面显示
    // ...
}